Rhabdomyosarcoma

Behind Olaratumab's Phase 3 Disappointment

ANNOUNCE, the phase 3 trial designed to confirm the clinical benefit of olaratumab in patients with advanced soft tissue sarcoma (STS), failed to meet its primary endpoint of overall survival (OS) in all STS histologies and the leiomyosarcoma population. The previous phase 1b/2 signal-finding study of olaratumab had achieved an unprecedented improvement in OS, and the US Food and Drug Administration (FDA) awarded olaratumab accelerated approval in October 2016. By December 2018, olaratumab received additional accelerated, conditional, and full approvals in more than 40 countries worldwide. William D. Tap, MD, chief of the Sarcoma Medical Oncology Service at Memorial Sloan Kettering Cancer Center in New York, presented the phase 3 results and provided some explanations for the findings during the plenary session at ASCO.

ANNOUNCE (NCT02451943), which was designed and enrolled prior to olaratumab receiving accelerated approval, opened in September 2015 and completed accrual 10 months later in July 2016. Investigators randomized and treated 509 patients with advanced STS not amenable to curative therapy, 258 patients in the olaratumab-doxorubicin arm and 251 in the placebo-doxorubicin arm. Most patients (46%) had leiomyosarcoma, followed by liposarcoma (18%), pleomorphic sarcoma (13%), and 24% of the patient population had 26 unique histologies. Three-quarters of the patients had no prior systemic therapy.

Results

As of the data cutoff on December 5, 2018, there were no survival differences in the intention-to-treat population, in the total STS population nor in the leiomyosarcoma subpopulation, with olaratumab-doxorubicin compared to placebo-doxorubicin. For the total STS population, median OS with olaratumab- doxorubicin was 20.4 months and with placebo-doxorubicin 19.7 months. “This is the highest survival rate described to date in any phase 3 sarcoma study,” Dr. Tap said. “It is of particular interest as ANNOUNCE did not mandate treatment in the first line.” In the leiomyosarcoma population, median OS was 21.6 months with olaratumab and 21.9 months with placebo. The secondary endpoints of progression-free survival (PFS), overall response rate, and disease control rate did not favor olaratumab either.

Investigators are examining the relationship between PDGFRα expression and OS in ANNOUNCE. PDGFRα-positive tumors tended to do worse with olaratumab than PDGFRα-negative tumors. The investigators noticed a 6-month difference in OS between these populations favoring PDGFRα-negative tumors. Additional biomarker analyses are ongoing.

A large and concerted effort is underway, Dr. Tap said, to understand the results of the ANNOUNCE study alone and in context with the phase 1b/2 study. “There are no noted discrepancies in study conduct or data integrity which could explain these findings or the differences between the two studies.”

Possible explanations

The designs of the phase 1b/2 and phase 3 studies had some important differences. The phase 1b/2 study was a small, open-label, US-centric study (10 sites) that did not include a placebo or subtype- specified analyses. Its primary endpoint was PFS, it did not have a loading dose of olaratumab, and it specified the timing of dexrazoxane administration after 300 mg/m2 of doxorubicin.

ANNOUNCE, on the other hand, was a large (n=509), international (110 study sites), double-blind, placebo-controlled trial that had outcomes evaluated in STS and leiomyosarcoma. Its primary endpoint was OS, it had a loading dose of olaratumab of 20 mg/kg, and there was no restriction as to the timing of dexrazoxane administration.

Dr. Tap pointed out that in ANNOUNCE it was difficult to predict or control for factors that may have had an unanticipated influence on outcomes, such as albumin levels as a surrogate for disease burden and behavior of PDGFRα status. It is possible, he said, that olaratumab has no activity in STS and that the phase 1b/2 results were due to, among other things, the small sample size, numerous represented histologies with disparate clinical behavior, and the effect of subtype-specific therapies on overall survival, given subsequently or even by chance. On the other hand, it is also possible, he said, that olaratumab has some activity in STS, with outcomes being affected by the heterogeneity of the study populations, differences in trial design, and the performance of the ANNOUNCE control arm. Whatever the case, he said, accelerated approval allowed patients to have access to a potentially life-prolonging drug with little added toxicity.

Discussion

In the expert discussion following the presentation, Jaap Verweij, MD, PhD, of Erasmus University Medical Center in Rotterdam, The Netherlands, congratulated the investigators for performing the study at an unprecedented pace. He commented that lumping STS subtypes together is problematic, as different histological subtypes behave as though they are different diseases. Small numbers of each tumor subtype and subtypes with slow tumor growth can impact trial outcomes. In the phase 1b/2 and phase 3 trials, 26 different subtypes were represented in each study. Dr. Verweij pointed out this could have made a big difference in the phase 1b/2 study, in which there were only 66 patients in each arm.

It is striking to note, he said, that without exception, phase 2 randomized studies in STS involving doxorubicin consistently overestimated and wrongly predicted PFS in the subsequent phase 3 studies. And the situation is similar for OS. The results of the ANNOUNCE study are no exception, he added. “Taken together, these studies indicate that phase 2 studies in soft tissue sarcomas, certainly those involving additions of drugs to doxorubicin, even if randomized, should be interpreted with great caution,” he said.

SOURCE: Tap WD, et al. J Clin Oncol 37, 2019 (suppl; abstr LBA3)

The study was sponsored by Eli Lilly and Company.

Dr. Tap reported research funding from Lilly and Dr. Verweij had nothing to report related to this study. Abstract coauthors disclosed numerous financial relationships, including consulting/advisory roles and/or research funding from Lilly, and several were employed by Lilly.

Addition of Temozolomide May Improve Outcomes in RMS

Investigators from the European Pediatric Soft Tissue Sarcoma Study Group (EpSSG) found that the addition of temozolomide (T) to vincristine and irinotecan (VI) may improve outcomes in adults and children with relapsed or refractory rhabdomyosarcoma (RMS). Principal investigator of the study, Anne Sophie Defachelles, MD, pediatric oncologist at the Centre Oscar Lambret in Lille, France, presented the results on behalf of the EpSSG.

The international, randomized (1:1), open-label, phase 2 trial (VIT-0910; NCT01355445) was conducted at 37 centers in 5 countries. Patients ages 6 months to 50 years with RMS were eligible. They could not have had prior irinotecan or temozolomide. A 2015 protocol amendment limited enrollment to patients at relapse and increased the enrollment goal by 40 patients. After the 2015 amendment, patients with refractory disease were no longer eligible.

From January 2012 to April 2018, investigators enrolled 120 patients, 60 on each arm. Two patients in the VI arm were not treated. Patients were a median age of 10.5 years in the VI arm and 12 years in the VIT arm, 92% (VI) and 87% (VIT) had relapsed disease, 8% (VI) and 13% (VIT) had refractory disease, and 55% (VI) and 68% (VIT) had metastatic disease at study entry.

Results

Patients achieved an OR rate of 44% (VIT) and 31% (VI) for the whole population, one-sided P value <.0001. The adjusted odds ratio for the whole population was 0.50, P=.09. PFS was 4.7 months (VIT) and 3.2 months (VI), “a nearly significant reduction in the risk of progression,” Dr. Defachelles noted. Median OS was 15.0 months (VIT) and 10.3 months (VI), which amounted to “a large and significant reduction in the risk of death,” she said. The adjusted hazard ratio was 0.55, P=.006.

Adverse events of grade 3 or higher were more frequent in the VIT arm, with hematologic toxicity the most frequent (81% for VIT, 59% for VI), followed by gastrointestinal adverse events. “VIT was significantly more toxic than VI,” Dr. Defachelles observed, “but the toxicity was manageable.”

“VIT is now the standard treatment in Europe for relapsed rhabdomyosarcoma and will be the control arm in the multiarm, multistage RMS study for relapsed patients,” she said.

SOURCE: Defachelles AS, et al. J Clin Oncol 37, 2019 (suppl; abstr 10000)

The study was sponsored by Centre Oscar Lambret and SFCE (Société Française de Lutte contre les Cancers et Lucémies de l’Enfant et de l’Adolescent) served as collaborator.

Drs. Defachelles and Wagner had no relationships to disclose. A few coauthors had advisory/consulting or speaker roles for various commercial interests, including two for Merck (temozolomide).

Pazopanib Increases Pathologic Necrosis Rates in STS

Pazopanib added to a regimen of preoperative chemoradiation in non-rhabdomyosarcoma soft tissue sarcoma (NRSTS) significantly increased the rate of near-complete pathologic response in both children and adults with intermediate or high-risk disease. Pazopanib, a multitargeted receptor tyrosine kinase inhibitor, works in multiple signaling pathways involved in tumorigenesis— VEGFR-1, -2, -3, PDGFRα/β, and c-kit. A phase 3 study demonstrated significant improvement in progression-free survival (PFS) in advanced STS patients and was the basis for its approval in the US and elsewhere for treatment of this patient population. Preclinical data suggest synergy between pazopanib and cytotoxic chemotherapy, forming the rationale for the current trial with neoadjuvant pazopanib added to chemoradiation.

According to the investigators, the trial (ARST1321) is the first ever collaborative study codeveloped, written, and conducted by pediatric (Children’s Oncology Group) and adult (NRG Oncology) cancer cooperative groups (NCT02180867). Aaron R. Weiss, MD, of the Maine Medical Center in Portland and study cochair, presented the data for the chemotherapy arms at ASCO. The primary objectives of the study were to determine the feasibility of preoperative chemoradiation with or without pazopanib and to compare the rates of complete pathologic response in patients receiving radiation or chemoradiation with or without pazopanib. Pathologic necrosis rates of 90% or better have been found to be predictive of outcome in STS.

Results

As of the June 30, 2018, cutoff, 81 patients were enrolled on the chemotherapy arms: 42 in the pazopanib plus chemoradiation arm and 39 in the chemoradiation-only arm. Sixty-one percent of all patients were 18 years or older, and the median age was 20.3 years. Most patients (73%) did not have metastatic disease, and the major histologies represented were synovial sarcoma (49%) and undifferentiated pleomorphic sarcoma (25%).

At week 13, patients in the pazopanib arm showed significant improvement, with 14 (58%) of those evaluated having pathologic necrosis of at least 90%, compared with 4 (22%) in the chemoradiation-only arm (P=.02). The study was closed to further accrual.

Eighteen patients were not evaluable for pathologic response and 21 were pending pathologic evaluation at week 13. Radiographic response rates were not statistically significant on either arm. No complete responses (CR) were achieved in the pazopanib arm, but 14 patients (52%) achieved a partial response (PR) and 12 (44%) had stable disease (SD). In the chemoradiation-only arm, 2 patients (8%) achieved a CR, 12 (50%) a PR, and 8 (33%) SD. Fifteen patients in each arm were not evaluated for radiographic response.

The pazopanib arm experienced more febrile neutropenia and myelotoxicity during induction and continuation phases than the chemoradiation-only arm. In general, investigators indicated pazopanib combined with chemoradiation was well tolerated and no unexpected toxicities arose during the trial.

In the post-presentation discussion, Dr. Raphael E. Pollock, MD, PhD, of The Ohio State University, called it a tremendous challenge to interdigitate primary local therapies in systemic approaches, particularly in the neoadjuvant context. He pointed out that in an earlier study, a 95% to 100% necrosis level was needed to achieve a significant positive impact on outcomes and perhaps a subsequent prospective trial could determine the best level. He questioned whether the availability of only 60% of patient responses could affect the conclusions and whether the high number of toxicities (73.8% grade 3/4 with pazopanib) might be too high to consider the treatment for most patients, given the intensity of the regimen.

SOURCE: Weiss AR, et al. J Clin Oncol 37, 2019 (suppl; abstr 11002)

The study was sponsored by the National Cancer Institute.

Drs. Weiss and Pollock had no relationships with commercial interests to disclose. A few investigators disclosed advisory, consulting, or research roles with pharmaceutical companies, including one who received institutional research funding from Novartis (pazopanib).

Gemcitabine Plus Pazopanib a Potential Alternative in STS

In a phase 2 study of gemcitabine with pazopanib (G+P) or gemcitabine with docetaxel (G+D), investigators concluded the combination with pazopanib can be considered an alternative to that with docetaxel in select patients with advanced soft tissue sarcoma (STS). They reported similar progression-free survival (PFS) and rate of toxicity for the two regimens. Neeta Somaiah, MD, of the University of Texas MD Anderson Cancer Center in Houston, presented the findings of the investigator-initiated effort (NCT01593748) at ASCO.

The investigators enrolled 90 patients, 45 in each arm. Patients were a mean age of 56 years, and there was no difference in age or gender distribution between the arms. Patients with leiomyosarcoma (31% overall) or prior pelvic radiation (11% overall) were similar between the arms. The overall response rate using RECIST 1.1 criteria was partial response (PR) in 8 of 44 evaluable patients (18%) in the G+D arm and 5 of 43 evaluable patients (12%) in the G+P arm. Stable disease (SD) was observed in 21 patients (48%) in the G+D arm and 24 patients (56%) in the G+P arm. This amounted to a clinical benefit rate (PR + SD) of 66% and 68% for the G+D and G+P arms, respectively (Fisher’s exact test, P>.99). The median PFS was 4.1 months on both arms and the difference in median overall survival— 15.9 months in the G+D arm and 12.4 months in the G+P arm—was not statistically significant.

Adverse events (AEs) of grade 3 or higher occurred in 19.9% of patients on G+D and 20.6% on G+P. Serious AEs occurred in 33% (G+D) and 22% (G+P). Dose reductions were necessary in 80% of patients on G+P and doses were held in 93%. Dr. Somaiah explained that this may have been because the starting dose of gemcitabine and pazopanib (1000 mg/m² of gemcitabine on days 1 and 8 and 800 mg of pazopanib) was “probably higher than what we should have started at.” The rate of doses held was also higher in the pazopanib arm (93%) compared with the docetaxel arm (58%). This was likely because pazopanib was a daily dosing, so if there was a toxicity it was more likely to be held than docetaxel, she observed. Grade 3 or higher toxicities occurring in 5% or more of patients in either arm consisted generally of cytopenias and fatigue. The G+P arm experienced a high amount of neutropenia, most likely because this arm did not receive granulocyte-colony stimulating factor (GCSF) support, as opposed to the G+D arm.

Dr. Somaiah pointed out that the 12% response rate for the G+P combination is similar to what has been previously presented and higher than single-agent gemcitabine or pazopanib, but not higher than the G+D combination. The PFS of 4.1 months was less than anticipated, she added, but it was similar on both arms. The investigators believe the G+P combination warrants further exploration.

SOURCE: Somaiah N, et al. J Clin Oncol 37, 2019 (suppl; abstr 11008)

The study was sponsored by the Medical University of South Carolina, with Novartis as collaborator.

Dr. Somaiah disclosed Advisory Board roles for Blueprint, Deciphera, and Bayer. Abstract coauthors disclosed advisory/consulting roles or research funding from various commercial interests, including Novartis (pazopanib) and Pfizer (gemcitabine).

rEECur Trial Finding Optimal Chemotherapy Regimen for Ewing Sarcoma

Interim results of the first and largest randomized trial in patients with refractory or recurrent Ewing sarcoma (ES), the rEECur trial, are guiding the way to finding the optimal chemotherapy regimen to treat the disease. Until now, there has been little prospective evidence and no randomized data to guide treatment choices in relapsed or refractory patients, and hence no real standard of care, according to the presentation at ASCO. Several molecularly targeted therapies are emerging, and they require a standardized chemotherapy backbone against which they can be tested.

Results

Two hundred twenty patients 4 years or older and younger than 50 years with recurrent or refractory histologically confirmed ES of bone or soft tissue were randomized to receive GD (n=72) or TC, IT, or IFOS (n=148). Sixty-two GD patients and 123 TC/IT/IFOS patients were included in the primary outcome analysis. Patients were predominantly male (70%), with a median age of 19 years (range, 4 to 49). About two-thirds (67.3%) were post-pubertal. Most patients (85%) were primary refractory or experienced their first disease recurrence, and 89% had measurable disease.

Investigators assessed the primary outcome of objective response after 4 cycles of therapy and found 11% of patients treated with GD responded compared to 24% in the other 3 arms combined. When they subjected the data to Bayesian analysis, there was a 25% chance that the response rate in the GD arm was better than the response in Arm A, a 2% chance that it was better than Arm B, and a 3% chance that it was better than Arm C. Because this study was still blinded at the time of the presentation, investigators didn’t know which regimen constituted which arm. The probability that response favored GD, however, was low.

The investigators observed no surprising safety findings. Eighty-five percent of all patients experienced at least 1 adverse event. Most frequent grade 3‐5 events consisted of pneumonitis (50%, 60%), neutropenic fever (17%, 25%), and diarrhea (0, 12%) in GD and the combined 3 arms, respectively. Grade 3 events in the GD arm were lower than in the other 3 arms combined. There was 1 toxic death attributed to neutropenic sepsis in 1 of the 3 blinded arms.

Median progression-free survival (PFS) for all patients was approximately 5 months. Bayesian analysis suggested there was a low probability that GD was more effective than the other 3 arms: a 22% chance that GD was better than Arm A, a 3% chance that it was better than Arm B, and a 7% chance that it was better than Arm C. Bayesian analysis also suggested there was a probability that OS favored GD. Because the trial directs only the first 4 or 6 cycles of treatment and the patients receive more treatment after trial-directed therapy, investigators were not fully able to interpret this.

Data suggested GD is a less effective regimen than the other 3 regimens both by objective response rate and PFS, so GD has been dropped from the study. Investigators already had more than 75 evaluable patients in each of the 3 arms for the second interim analysis to take place. In a discussion following the presentation, Jayesh Desai, FRACP, of Peter MacCallum Cancer Centre in Melbourne, Australia, called this study a potentially practice-changing trial at this early stage, noting that the GD combination will be de-prioritized in practice based on these results.

SOURCE: McCabe MG, et al. J Clin Oncol 37, 2019 (suppl; abstr 11007)

The rEECur trial is sponsored by the University of Birmingham (UK) and received funding from the European Union’s Seventh Framework Programme under a grant agreement.

Dr. McCabe disclosed no conflicts of interest. Other authors disclosed consulting, advisory roles, or research funding from numerous pharmaceutical companies, including Lilly (gemcitabine) and Pfizer (irinotecan). Dr. Desai disclosed a consulting/advisory role and institutional research funding from Lilly.

Abemaciclib Meets Primary Endpoint in Phase 2 Trial of DDLS

The newer and more potent CDK4 inhibitor, abemaciclib, met its primary endpoint in the investigator-initiated, single-center, single-arm, phase 2 trial in patients with advanced progressive dedifferentiated liposarcoma (DDLS). Twenty-two patients (76%) achieved progression-free survival (PFS) at 12 weeks for a median PFS of 30 weeks. A subset of patients experienced prolonged clinical benefit, remaining on study with stable disease for over 900 days. The study (NCT02846987) was conducted at Memorial Sloan Kettering Cancer Center (MSKCC) in New York and Mark A. Dickson, MD, presented the results at ASCO.

Results

Thirty patients, 29 evaluable, with metastatic or recurrent DDLS were enrolled and treated with abemaciclib 200 mg orally twice daily between August 2016 and October 2018. Data cutoff for the presentation was the first week of May 2019. Patients were a median of 62 years, 60% were male, and half had no prior systemic treatment. Prior systemic treatments for those previously treated included doxorubicin, olaratumab, gemcitabine, docetaxel, ifosfamide, eribulin, and trabectedin. For 87%, the primary tumor was in their abdomen or retroperitoneum.

Toxicity was as expected with this class of agent, according to the investigators. The most common grades 2 and 3 toxicities, respectively, possibly related to the study drug, occurring in more than 1 patient included anemia (70%, 37%), thrombocytopenia (13%, 13%), neutropenia (43%, 17%), and lymphocyte count decreased (23%, 23%). Very few of these adverse events were grade 4—none for anemia, and 3% each for thrombocytopenia, neutropenia, and lymphocyte count decreased. Diarrhea of grades 2 and 3 occurred in 27% and 7% of patients, respectively, and was managed well with loperamide.

In addition to reaching the primary endpoint of 15 patients or more achieving PFS at 12 weeks, 1 patient had a confirmed partial response (PR) and another an unconfirmed PR. At data cutoff, 11 patients remained on study with stable disease or PR. The investigators conducted correlative studies that indicated all patients had CDK4 and MDM2 amplification with no loss of retinoblastoma tumor suppressor. They observed an inverse correlation between CDK4 amplification and PFS—the higher the level of CDK4 amplification, the shorter the PFS. They also found additional genomic alterations, including JUN, GLI1, ARID1A, TERT, and ATRX. TERT amplification was also associated with shorter PFS. Based on these findings, the investigators believe a phase 3 study of abemaciclib in DDLS is warranted.

Winette van der Graaf, MD, PhD, of the Netherlands Cancer Institute in Amsterdam, in the discussion following the presentation, concurred that it is certainly time for a multicenter phase 3 study of CDK4 inhibitors in DDLS, and a strong international collaboration is key to conducting such studies, particularly in rare cancers. On a critical note, Dr. van der Graaf expressed concern that no patient-reported outcomes were measured after 120 patients, including those in previous studies, were treated on palbociclib and abemaciclib. Given that the toxicities of the CDK4 inhibitors are quite different, she recommended including patient-reported outcomes in future studies using validated health-related quality-of-life instruments.

SOURCE: Dickson MA, et al. J Clin Oncol 37, 2019 (suppl; abstr 11004)

The study was sponsored by Memorial Sloan Kettering Cancer Center, with the study collaborator, Eli Lilly and Company.

Dr. Dickson disclosed research funding from Lilly, the company that provided the study drug. Dr. van der Graaf had no relevant relationships to disclose. Abstract coauthors had consulting/advisory roles or research funding from various companies, including Lilly.

nab-Sirolimus Provides Benefits in Advanced Malignant PEComa

In a prospective phase 2 study of nab-sirolimus in advanced malignant perivascular epithelioid cell tumor (PEComa), the mTOR inhibitor achieved an objective response rate (ORR) of 42% with an acceptable safety profile, despite using relatively high doses of nab-sirolimus compared to other mTOR inhibitors. Activation of the mTOR pathway is common in PEComa, and earlier case reports had indicated substantial clinical benefit with mTOR inhibitor treatment. nab-Sirolimus (ABI-009) is a novel intravenous mTOR inhibitor consisting of nanoparticles of albumin-bound sirolimus. It has significantly higher anti-tumor activity than oral mTOR inhibitors and greater mTOR target suppression at an equal dose. Andrew J. Wagner, MD, PhD, of the Dana-Farber Cancer Institute in Boston, presented the findings of AMPECT (NCT02494570)—Advanced Malignant PEComa Trial—at ASCO.

Results

The drug was well tolerated, with toxicities similar to those of oral mTOR inhibitors. Treatment-related adverse events (TRAEs) occurring in 25% or more of patients were mostly grade 1 or 2 toxicities. Hematologic TRAEs included anemia (47%) and thrombocytopenia (32%) of any grade. Nonhematologic events of any grade included stomatitis/ mucositis (74%), dermatitis/rash (65%), fatigue (59%), nausea (47%), and diarrhea (38%), among others. A few grade 3 events occurred on study, most notably stomatitis/mucositis (18%). Severe adverse events (SAEs) were also uncommon, occurring in 7 of 34 patients (21%). Pneumonitis is common in orally administered mTOR inhibitors; 6 patients (18%) treated with nab-sirolimus had grade 1 or 2 pneumonitis.

Of the 31 evaluable patients, 13 (42%) had an objective response, all of which were partial responses (PR). Eleven (35%) had stable disease and 7 (23%) had progressive disease. The disease control rate, consisting of PR and stable disease, was 77%. The median duration of response had not been reached as of the data cutoff on May 10, 2019. At that time, it was 6.2 months (range, 1.5 to 27.7+). The median time to response was 1.4 months and the median progression-free survival (PFS) was 8.4 months. The PFS rate at 6 months was 61%. Three patients had received treatment for over a year and another 3 patients for more than 2 years.

Correlation with biomarkers

Of the 25 patients who had tissue suitable for next-generation sequencing, 9 had TSC2 mutations, 5 had TSC1 mutations, and 11 had neither mutation. Strikingly, 9 of 9 patients with TSC2 mutations developed a PR, while only 1 with a TSC1 mutation responded. One patient with no TSC1/2 mutation also responded and 2 patients with unknown mutational status responded. The investigators also analyzed pS6 status by immunohistochemistry—pS6 is a marker of mTOR hyperactivity. Twenty- five patient samples were available for analysis. Eight of 8 patients who were negative for pS6 staining did not have a response, while 10 of 17 (59%) who were pS6-positive had a PR.

In the discussion that followed, Winette van der Graaf, MD, of the Netherlands Cancer Institute in Amsterdam, noted that this study showed that biomarkers can be used for patient selection, although TSC2 mutations are not uniquely linked with response. She indicated a comparator with sirolimus would have been of great interest.

SOURCE: Wagner AJ, et al. J Clin Oncol 37, 2019 (suppl; abstr 11005).

The study was sponsored by Aadi Bioscience, Inc., and funded in part by a grant from the FDA Office of Orphan Products Development (OOPD).

Disclosures relevant to this presentation include contininstitutional research funding from Aadi Bioscience for Dr. Wagner and a few other abstract coauthors. Several coauthors are employed by Aadi Bioscience and have stock or other ownership interests. Dr. van der Graaf had nothing to disclose.

Cabozantinib Achieves Disease Control in GIST

The phase 2 EORTC 1317 trial, known as CaboGIST (NCT02216578), met its primary endpoint of progression-free survival (PFS) at 12 weeks in patients with metastatic gastrointestinal stromal tumor (GIST) treated with the tyrosine kinase inhibitor (TKI) cabozantinib. Twenty-four (58.5%) of the 41 patients in the primary study population, and 30 (60%) of the entire 50-patient population, were progression-free at 12 weeks. The study needed 21 patients to be progression- free for cabozantinib to warrant further exploration in GIST patients.

This investigator-initiated study had as its primary objective assessment of the safety and activity of cabozantinib in patients with metastatic GIST who had progressed on imatinib and sunitinib. The patients could not have been exposed to other KIT- or PDGFR-directed TKIs, such as regorafenib. Secondary objectives included the assessment of cabozantinib in different mutational subtypes of GIST. Patients received cabozantinib tablets once daily until they experienced no further clinical benefit or became intolerant to the drug or chose to discontinue therapy. Fifty patients started treatment between February 2017 and August 2018. All were evaluable for the primary endpoint, and one-third of patients contininstitutional cabozantinib treatment as of the database cutoff in January 2019.

Results

Patients were a median age of 63 years. Virtually all patients (92%) had prior surgery and only 8% had prior radiotherapy. The daily cabozantinib dose was a median 47.2 mg and duration of treatment was a median 20.4 weeks. No patient discontinued treatment due to toxicity, but 88% discontinued due to disease progression.

Safety signals were the same as for other indications in which cabozantinib is used. Almost all patients (94%) had at least 1 treatment-related adverse event of grades 1‐4, including diarrhea (74%), palmar-plantar erythrodysesthesia (58%), fatigue (46%), and hypertension (46%), which are typical of treatment with cabozantinib. Hematologic toxicities in this trial were clinically irrelevant, according to the investigators, consisting of small numbers of grades 2‐3 anemia, lymphopenia, white blood cell count abnormality, and neutropenia. Biochemical abnormalities included grades 3 and 4 hypophosphatemia, increased grades 3 and 4 gamma-glutamyl transferase, grade 3 hyponatremia, and grade 3 hypokalemia, in 8% or more of patients.

Overall survival was a median 14.4 months, with 16 patients still on treatment at the time of data cutoff. Twenty- four patients were progression-free at week 12, satisfying the study decision rule for clinical benefit. Median duration of PFS was 6.0 months. Seven patients (14%) achieved a confirmed partial response (PR) and 33 (66%) achieved stable disease (SD). Nine patients had progressive disease as their best response, 3 of whom had some clinical benefit. Forty patients (80%) experienced a clinical benefit of disease control (PR + SD).

An analysis of the relationship of genotype, duration, and RECIST response showed objective responses in patients with primary exon 11 mutations, with exon 9 mutations, and with exon 17 mutations, and in 2 patients without any known mutational information at the time of the presentation. Patients with stable disease were spread across all mutational subsets in the trial. The investigators suggested the definitive role of MET and AXL inhibition in GIST be assessed further in future clinical trials.

SOURCE: Schöffski P, et al. J Clin Oncol 37, 2019 (suppl; abstr 11006).

The study was sponsored by the European Organization for Research and Treatment of Cancer (EORTC).

Presenting author, Patrick Schöffski, MD, of KU Leuven and Leuven Cancer Institute in Belgium, disclosed institutional relationships with multiple pharmaceutical companies for consulting and research funding, including research funding from Exelixis, the developer of cabozantinib. No other abstract coauthor disclosed a relationship with Exelixis.

Larotectinib Effective in TRK Fusion Cancers

Pediatric patients with tropomyosin receptor kinase (TRK) fusions involving NTRK1, NTRK2, and NTRK3 genes had a high response rate with durable responses and a favorable safety profile when treated with larotrectinib, according to a presentation at ASCO. In this pediatric subset of children and adolescents from the SCOUT and NAVIGATE studies, the overall response rate (ORR) was 94%, with a 35% complete response (CR), 59% partial response (PR), and 6% stable disease as of the data cutoff at the end of July 2018.

Investigators enrolled 38 children and adolescents younger than 18 years from the SCOUT (NCT02637687) and NAVIGATE (NCT02576431) studies of larotrectinib who had non-central nervous system (CNS) TRK fusion cancers. Not all patients had the recommended phase 2 dose, Dr. van Tilburg pointed out, but most did. Hence, 29 of the 38 patients received the 100 mg/m² twice-daily, phase 2 dose until progression, withdrawal, or unacceptable toxicity.

Patients were young, with a median age of 2.3 years (range, 0.1 to 14.0 years). Almost two-thirds (61%) had prior surgery, 11% had prior radiotherapy, and 68% had prior systemic therapy. For 12 patients, larotrectinib was their first systemic therapy. The predominant tumor types were infantile fibrosarcoma (47%) and other soft tissue sarcoma (42%). And 47% of patients had NTRK3 fusions with ETV6, most of which were infantile fibrosarcoma.

Efficacy

Thirty-four patients were evaluable, and 32 had a reduction in tumor size, for an ORR of 94%, CR of 35%, and PR of 59%. Two patients with infantile fibrosarcoma had pathologic CRs—after treatment, no fibroid tissue in the tumors could be found. Median time to response was 1.8 months, median duration of treatment was 10.24 months, and 33 of 38 patients (87%) remained on treatment or underwent surgery with curative intent. As of the data cutoff of July 30, 2018, the secondary endpoints were not yet reached. However, 84% of responders were estimated to have a response duration of a year or more, and progression-free and overall survival looked very promising, according to Dr. van Tilburg.

Adverse events were primarily grades 1 and 2. The grades 3 and 4 treatment-related adverse events were quite few and consisted of increased alanine aminotransferase, decreased neutrophil count, and nausea. Longer follow-up of the patient safety profile is required, particularly since NTRK has multiple roles in neurodevelopment. The investigators recommended that routine testing for NTRK gene fusions in pediatric patients with cancer be conducted in appropriate clinical contexts.

In a discussion after the presentation, Daniel Alexander Morgenstern, MB BChir, PhD, of Great Ormond Street Hospital, London, UK, said that in many ways, the NTRK inhibitors have become the new poster child for precision oncology in pediatrics because of “these really spectacular results” with larotrectinib [and entrectinib]. One of the questions he raised regarding larotrectinib was the issue of CNS penetration, since patients with CNS cancer were not enrolled in the trial and preclinical data suggest limited CNS penetration for larotrectinib.

SOURCE: van Tilburg CM, et al. J Clin Oncol 37, 2019 (suppl; abstr 10010).

The studies were funded by Loxo Oncology, Inc., and Bayer AG.

Disclosures relevant to this presentation include consulting or advisory roles for Bayer for Drs. van Tilburg and Morgenstern. A few coauthors also had consulting/advisory roles or research funding from various companies, including Loxo and Bayer.

Behind Olaratumab's Phase 3 Disappointment

ANNOUNCE, the phase 3 trial designed to confirm the clinical benefit of olaratumab in patients with advanced soft tissue sarcoma (STS), failed to meet its primary endpoint of overall survival (OS) in all STS histologies and the leiomyosarcoma population. The previous phase 1b/2 signal-finding study of olaratumab had achieved an unprecedented improvement in OS, and the US Food and Drug Administration (FDA) awarded olaratumab accelerated approval in October 2016. By December 2018, olaratumab received additional accelerated, conditional, and full approvals in more than 40 countries worldwide. William D. Tap, MD, chief of the Sarcoma Medical Oncology Service at Memorial Sloan Kettering Cancer Center in New York, presented the phase 3 results and provided some explanations for the findings during the plenary session at ASCO.

ANNOUNCE (NCT02451943), which was designed and enrolled prior to olaratumab receiving accelerated approval, opened in September 2015 and completed accrual 10 months later in July 2016. Investigators randomized and treated 509 patients with advanced STS not amenable to curative therapy, 258 patients in the olaratumab-doxorubicin arm and 251 in the placebo-doxorubicin arm. Most patients (46%) had leiomyosarcoma, followed by liposarcoma (18%), pleomorphic sarcoma (13%), and 24% of the patient population had 26 unique histologies. Three-quarters of the patients had no prior systemic therapy.

Results

As of the data cutoff on December 5, 2018, there were no survival differences in the intention-to-treat population, in the total STS population nor in the leiomyosarcoma subpopulation, with olaratumab-doxorubicin compared to placebo-doxorubicin. For the total STS population, median OS with olaratumab- doxorubicin was 20.4 months and with placebo-doxorubicin 19.7 months. “This is the highest survival rate described to date in any phase 3 sarcoma study,” Dr. Tap said. “It is of particular interest as ANNOUNCE did not mandate treatment in the first line.” In the leiomyosarcoma population, median OS was 21.6 months with olaratumab and 21.9 months with placebo. The secondary endpoints of progression-free survival (PFS), overall response rate, and disease control rate did not favor olaratumab either.

Investigators are examining the relationship between PDGFRα expression and OS in ANNOUNCE. PDGFRα-positive tumors tended to do worse with olaratumab than PDGFRα-negative tumors. The investigators noticed a 6-month difference in OS between these populations favoring PDGFRα-negative tumors. Additional biomarker analyses are ongoing.

A large and concerted effort is underway, Dr. Tap said, to understand the results of the ANNOUNCE study alone and in context with the phase 1b/2 study. “There are no noted discrepancies in study conduct or data integrity which could explain these findings or the differences between the two studies.”

Possible explanations

The designs of the phase 1b/2 and phase 3 studies had some important differences. The phase 1b/2 study was a small, open-label, US-centric study (10 sites) that did not include a placebo or subtype- specified analyses. Its primary endpoint was PFS, it did not have a loading dose of olaratumab, and it specified the timing of dexrazoxane administration after 300 mg/m2 of doxorubicin.

ANNOUNCE, on the other hand, was a large (n=509), international (110 study sites), double-blind, placebo-controlled trial that had outcomes evaluated in STS and leiomyosarcoma. Its primary endpoint was OS, it had a loading dose of olaratumab of 20 mg/kg, and there was no restriction as to the timing of dexrazoxane administration.

Dr. Tap pointed out that in ANNOUNCE it was difficult to predict or control for factors that may have had an unanticipated influence on outcomes, such as albumin levels as a surrogate for disease burden and behavior of PDGFRα status. It is possible, he said, that olaratumab has no activity in STS and that the phase 1b/2 results were due to, among other things, the small sample size, numerous represented histologies with disparate clinical behavior, and the effect of subtype-specific therapies on overall survival, given subsequently or even by chance. On the other hand, it is also possible, he said, that olaratumab has some activity in STS, with outcomes being affected by the heterogeneity of the study populations, differences in trial design, and the performance of the ANNOUNCE control arm. Whatever the case, he said, accelerated approval allowed patients to have access to a potentially life-prolonging drug with little added toxicity.

Discussion

In the expert discussion following the presentation, Jaap Verweij, MD, PhD, of Erasmus University Medical Center in Rotterdam, The Netherlands, congratulated the investigators for performing the study at an unprecedented pace. He commented that lumping STS subtypes together is problematic, as different histological subtypes behave as though they are different diseases. Small numbers of each tumor subtype and subtypes with slow tumor growth can impact trial outcomes. In the phase 1b/2 and phase 3 trials, 26 different subtypes were represented in each study. Dr. Verweij pointed out this could have made a big difference in the phase 1b/2 study, in which there were only 66 patients in each arm.

It is striking to note, he said, that without exception, phase 2 randomized studies in STS involving doxorubicin consistently overestimated and wrongly predicted PFS in the subsequent phase 3 studies. And the situation is similar for OS. The results of the ANNOUNCE study are no exception, he added. “Taken together, these studies indicate that phase 2 studies in soft tissue sarcomas, certainly those involving additions of drugs to doxorubicin, even if randomized, should be interpreted with great caution,” he said.

SOURCE: Tap WD, et al. J Clin Oncol 37, 2019 (suppl; abstr LBA3)

The study was sponsored by Eli Lilly and Company.

Dr. Tap reported research funding from Lilly and Dr. Verweij had nothing to report related to this study. Abstract coauthors disclosed numerous financial relationships, including consulting/advisory roles and/or research funding from Lilly, and several were employed by Lilly.

Addition of Temozolomide May Improve Outcomes in RMS

Investigators from the European Pediatric Soft Tissue Sarcoma Study Group (EpSSG) found that the addition of temozolomide (T) to vincristine and irinotecan (VI) may improve outcomes in adults and children with relapsed or refractory rhabdomyosarcoma (RMS). Principal investigator of the study, Anne Sophie Defachelles, MD, pediatric oncologist at the Centre Oscar Lambret in Lille, France, presented the results on behalf of the EpSSG.

The international, randomized (1:1), open-label, phase 2 trial (VIT-0910; NCT01355445) was conducted at 37 centers in 5 countries. Patients ages 6 months to 50 years with RMS were eligible. They could not have had prior irinotecan or temozolomide. A 2015 protocol amendment limited enrollment to patients at relapse and increased the enrollment goal by 40 patients. After the 2015 amendment, patients with refractory disease were no longer eligible.

From January 2012 to April 2018, investigators enrolled 120 patients, 60 on each arm. Two patients in the VI arm were not treated. Patients were a median age of 10.5 years in the VI arm and 12 years in the VIT arm, 92% (VI) and 87% (VIT) had relapsed disease, 8% (VI) and 13% (VIT) had refractory disease, and 55% (VI) and 68% (VIT) had metastatic disease at study entry.

Results

Patients achieved an OR rate of 44% (VIT) and 31% (VI) for the whole population, one-sided P value <.0001. The adjusted odds ratio for the whole population was 0.50, P=.09. PFS was 4.7 months (VIT) and 3.2 months (VI), “a nearly significant reduction in the risk of progression,” Dr. Defachelles noted. Median OS was 15.0 months (VIT) and 10.3 months (VI), which amounted to “a large and significant reduction in the risk of death,” she said. The adjusted hazard ratio was 0.55, P=.006.

Adverse events of grade 3 or higher were more frequent in the VIT arm, with hematologic toxicity the most frequent (81% for VIT, 59% for VI), followed by gastrointestinal adverse events. “VIT was significantly more toxic than VI,” Dr. Defachelles observed, “but the toxicity was manageable.”

“VIT is now the standard treatment in Europe for relapsed rhabdomyosarcoma and will be the control arm in the multiarm, multistage RMS study for relapsed patients,” she said.

SOURCE: Defachelles AS, et al. J Clin Oncol 37, 2019 (suppl; abstr 10000)

The study was sponsored by Centre Oscar Lambret and SFCE (Société Française de Lutte contre les Cancers et Lucémies de l’Enfant et de l’Adolescent) served as collaborator.

Drs. Defachelles and Wagner had no relationships to disclose. A few coauthors had advisory/consulting or speaker roles for various commercial interests, including two for Merck (temozolomide).

Pazopanib Increases Pathologic Necrosis Rates in STS

Pazopanib added to a regimen of preoperative chemoradiation in non-rhabdomyosarcoma soft tissue sarcoma (NRSTS) significantly increased the rate of near-complete pathologic response in both children and adults with intermediate or high-risk disease. Pazopanib, a multitargeted receptor tyrosine kinase inhibitor, works in multiple signaling pathways involved in tumorigenesis— VEGFR-1, -2, -3, PDGFRα/β, and c-kit. A phase 3 study demonstrated significant improvement in progression-free survival (PFS) in advanced STS patients and was the basis for its approval in the US and elsewhere for treatment of this patient population. Preclinical data suggest synergy between pazopanib and cytotoxic chemotherapy, forming the rationale for the current trial with neoadjuvant pazopanib added to chemoradiation.

According to the investigators, the trial (ARST1321) is the first ever collaborative study codeveloped, written, and conducted by pediatric (Children’s Oncology Group) and adult (NRG Oncology) cancer cooperative groups (NCT02180867). Aaron R. Weiss, MD, of the Maine Medical Center in Portland and study cochair, presented the data for the chemotherapy arms at ASCO. The primary objectives of the study were to determine the feasibility of preoperative chemoradiation with or without pazopanib and to compare the rates of complete pathologic response in patients receiving radiation or chemoradiation with or without pazopanib. Pathologic necrosis rates of 90% or better have been found to be predictive of outcome in STS.

Results

As of the June 30, 2018, cutoff, 81 patients were enrolled on the chemotherapy arms: 42 in the pazopanib plus chemoradiation arm and 39 in the chemoradiation-only arm. Sixty-one percent of all patients were 18 years or older, and the median age was 20.3 years. Most patients (73%) did not have metastatic disease, and the major histologies represented were synovial sarcoma (49%) and undifferentiated pleomorphic sarcoma (25%).

At week 13, patients in the pazopanib arm showed significant improvement, with 14 (58%) of those evaluated having pathologic necrosis of at least 90%, compared with 4 (22%) in the chemoradiation-only arm (P=.02). The study was closed to further accrual.

Eighteen patients were not evaluable for pathologic response and 21 were pending pathologic evaluation at week 13. Radiographic response rates were not statistically significant on either arm. No complete responses (CR) were achieved in the pazopanib arm, but 14 patients (52%) achieved a partial response (PR) and 12 (44%) had stable disease (SD). In the chemoradiation-only arm, 2 patients (8%) achieved a CR, 12 (50%) a PR, and 8 (33%) SD. Fifteen patients in each arm were not evaluated for radiographic response.

The pazopanib arm experienced more febrile neutropenia and myelotoxicity during induction and continuation phases than the chemoradiation-only arm. In general, investigators indicated pazopanib combined with chemoradiation was well tolerated and no unexpected toxicities arose during the trial.

In the post-presentation discussion, Dr. Raphael E. Pollock, MD, PhD, of The Ohio State University, called it a tremendous challenge to interdigitate primary local therapies in systemic approaches, particularly in the neoadjuvant context. He pointed out that in an earlier study, a 95% to 100% necrosis level was needed to achieve a significant positive impact on outcomes and perhaps a subsequent prospective trial could determine the best level. He questioned whether the availability of only 60% of patient responses could affect the conclusions and whether the high number of toxicities (73.8% grade 3/4 with pazopanib) might be too high to consider the treatment for most patients, given the intensity of the regimen.

SOURCE: Weiss AR, et al. J Clin Oncol 37, 2019 (suppl; abstr 11002)

The study was sponsored by the National Cancer Institute.

Drs. Weiss and Pollock had no relationships with commercial interests to disclose. A few investigators disclosed advisory, consulting, or research roles with pharmaceutical companies, including one who received institutional research funding from Novartis (pazopanib).

Gemcitabine Plus Pazopanib a Potential Alternative in STS

In a phase 2 study of gemcitabine with pazopanib (G+P) or gemcitabine with docetaxel (G+D), investigators concluded the combination with pazopanib can be considered an alternative to that with docetaxel in select patients with advanced soft tissue sarcoma (STS). They reported similar progression-free survival (PFS) and rate of toxicity for the two regimens. Neeta Somaiah, MD, of the University of Texas MD Anderson Cancer Center in Houston, presented the findings of the investigator-initiated effort (NCT01593748) at ASCO.

The investigators enrolled 90 patients, 45 in each arm. Patients were a mean age of 56 years, and there was no difference in age or gender distribution between the arms. Patients with leiomyosarcoma (31% overall) or prior pelvic radiation (11% overall) were similar between the arms. The overall response rate using RECIST 1.1 criteria was partial response (PR) in 8 of 44 evaluable patients (18%) in the G+D arm and 5 of 43 evaluable patients (12%) in the G+P arm. Stable disease (SD) was observed in 21 patients (48%) in the G+D arm and 24 patients (56%) in the G+P arm. This amounted to a clinical benefit rate (PR + SD) of 66% and 68% for the G+D and G+P arms, respectively (Fisher’s exact test, P>.99). The median PFS was 4.1 months on both arms and the difference in median overall survival— 15.9 months in the G+D arm and 12.4 months in the G+P arm—was not statistically significant.

Adverse events (AEs) of grade 3 or higher occurred in 19.9% of patients on G+D and 20.6% on G+P. Serious AEs occurred in 33% (G+D) and 22% (G+P). Dose reductions were necessary in 80% of patients on G+P and doses were held in 93%. Dr. Somaiah explained that this may have been because the starting dose of gemcitabine and pazopanib (1000 mg/m² of gemcitabine on days 1 and 8 and 800 mg of pazopanib) was “probably higher than what we should have started at.” The rate of doses held was also higher in the pazopanib arm (93%) compared with the docetaxel arm (58%). This was likely because pazopanib was a daily dosing, so if there was a toxicity it was more likely to be held than docetaxel, she observed. Grade 3 or higher toxicities occurring in 5% or more of patients in either arm consisted generally of cytopenias and fatigue. The G+P arm experienced a high amount of neutropenia, most likely because this arm did not receive granulocyte-colony stimulating factor (GCSF) support, as opposed to the G+D arm.

Dr. Somaiah pointed out that the 12% response rate for the G+P combination is similar to what has been previously presented and higher than single-agent gemcitabine or pazopanib, but not higher than the G+D combination. The PFS of 4.1 months was less than anticipated, she added, but it was similar on both arms. The investigators believe the G+P combination warrants further exploration.

SOURCE: Somaiah N, et al. J Clin Oncol 37, 2019 (suppl; abstr 11008)

The study was sponsored by the Medical University of South Carolina, with Novartis as collaborator.

Dr. Somaiah disclosed Advisory Board roles for Blueprint, Deciphera, and Bayer. Abstract coauthors disclosed advisory/consulting roles or research funding from various commercial interests, including Novartis (pazopanib) and Pfizer (gemcitabine).

rEECur Trial Finding Optimal Chemotherapy Regimen for Ewing Sarcoma

Interim results of the first and largest randomized trial in patients with refractory or recurrent Ewing sarcoma (ES), the rEECur trial, are guiding the way to finding the optimal chemotherapy regimen to treat the disease. Until now, there has been little prospective evidence and no randomized data to guide treatment choices in relapsed or refractory patients, and hence no real standard of care, according to the presentation at ASCO. Several molecularly targeted therapies are emerging, and they require a standardized chemotherapy backbone against which they can be tested.

Results

Two hundred twenty patients 4 years or older and younger than 50 years with recurrent or refractory histologically confirmed ES of bone or soft tissue were randomized to receive GD (n=72) or TC, IT, or IFOS (n=148). Sixty-two GD patients and 123 TC/IT/IFOS patients were included in the primary outcome analysis. Patients were predominantly male (70%), with a median age of 19 years (range, 4 to 49). About two-thirds (67.3%) were post-pubertal. Most patients (85%) were primary refractory or experienced their first disease recurrence, and 89% had measurable disease.

Investigators assessed the primary outcome of objective response after 4 cycles of therapy and found 11% of patients treated with GD responded compared to 24% in the other 3 arms combined. When they subjected the data to Bayesian analysis, there was a 25% chance that the response rate in the GD arm was better than the response in Arm A, a 2% chance that it was better than Arm B, and a 3% chance that it was better than Arm C. Because this study was still blinded at the time of the presentation, investigators didn’t know which regimen constituted which arm. The probability that response favored GD, however, was low.

The investigators observed no surprising safety findings. Eighty-five percent of all patients experienced at least 1 adverse event. Most frequent grade 3‐5 events consisted of pneumonitis (50%, 60%), neutropenic fever (17%, 25%), and diarrhea (0, 12%) in GD and the combined 3 arms, respectively. Grade 3 events in the GD arm were lower than in the other 3 arms combined. There was 1 toxic death attributed to neutropenic sepsis in 1 of the 3 blinded arms.

Median progression-free survival (PFS) for all patients was approximately 5 months. Bayesian analysis suggested there was a low probability that GD was more effective than the other 3 arms: a 22% chance that GD was better than Arm A, a 3% chance that it was better than Arm B, and a 7% chance that it was better than Arm C. Bayesian analysis also suggested there was a probability that OS favored GD. Because the trial directs only the first 4 or 6 cycles of treatment and the patients receive more treatment after trial-directed therapy, investigators were not fully able to interpret this.

Data suggested GD is a less effective regimen than the other 3 regimens both by objective response rate and PFS, so GD has been dropped from the study. Investigators already had more than 75 evaluable patients in each of the 3 arms for the second interim analysis to take place. In a discussion following the presentation, Jayesh Desai, FRACP, of Peter MacCallum Cancer Centre in Melbourne, Australia, called this study a potentially practice-changing trial at this early stage, noting that the GD combination will be de-prioritized in practice based on these results.

SOURCE: McCabe MG, et al. J Clin Oncol 37, 2019 (suppl; abstr 11007)

The rEECur trial is sponsored by the University of Birmingham (UK) and received funding from the European Union’s Seventh Framework Programme under a grant agreement.

Dr. McCabe disclosed no conflicts of interest. Other authors disclosed consulting, advisory roles, or research funding from numerous pharmaceutical companies, including Lilly (gemcitabine) and Pfizer (irinotecan). Dr. Desai disclosed a consulting/advisory role and institutional research funding from Lilly.

Abemaciclib Meets Primary Endpoint in Phase 2 Trial of DDLS

The newer and more potent CDK4 inhibitor, abemaciclib, met its primary endpoint in the investigator-initiated, single-center, single-arm, phase 2 trial in patients with advanced progressive dedifferentiated liposarcoma (DDLS). Twenty-two patients (76%) achieved progression-free survival (PFS) at 12 weeks for a median PFS of 30 weeks. A subset of patients experienced prolonged clinical benefit, remaining on study with stable disease for over 900 days. The study (NCT02846987) was conducted at Memorial Sloan Kettering Cancer Center (MSKCC) in New York and Mark A. Dickson, MD, presented the results at ASCO.

Results

Thirty patients, 29 evaluable, with metastatic or recurrent DDLS were enrolled and treated with abemaciclib 200 mg orally twice daily between August 2016 and October 2018. Data cutoff for the presentation was the first week of May 2019. Patients were a median of 62 years, 60% were male, and half had no prior systemic treatment. Prior systemic treatments for those previously treated included doxorubicin, olaratumab, gemcitabine, docetaxel, ifosfamide, eribulin, and trabectedin. For 87%, the primary tumor was in their abdomen or retroperitoneum.

Toxicity was as expected with this class of agent, according to the investigators. The most common grades 2 and 3 toxicities, respectively, possibly related to the study drug, occurring in more than 1 patient included anemia (70%, 37%), thrombocytopenia (13%, 13%), neutropenia (43%, 17%), and lymphocyte count decreased (23%, 23%). Very few of these adverse events were grade 4—none for anemia, and 3% each for thrombocytopenia, neutropenia, and lymphocyte count decreased. Diarrhea of grades 2 and 3 occurred in 27% and 7% of patients, respectively, and was managed well with loperamide.

In addition to reaching the primary endpoint of 15 patients or more achieving PFS at 12 weeks, 1 patient had a confirmed partial response (PR) and another an unconfirmed PR. At data cutoff, 11 patients remained on study with stable disease or PR. The investigators conducted correlative studies that indicated all patients had CDK4 and MDM2 amplification with no loss of retinoblastoma tumor suppressor. They observed an inverse correlation between CDK4 amplification and PFS—the higher the level of CDK4 amplification, the shorter the PFS. They also found additional genomic alterations, including JUN, GLI1, ARID1A, TERT, and ATRX. TERT amplification was also associated with shorter PFS. Based on these findings, the investigators believe a phase 3 study of abemaciclib in DDLS is warranted.

Winette van der Graaf, MD, PhD, of the Netherlands Cancer Institute in Amsterdam, in the discussion following the presentation, concurred that it is certainly time for a multicenter phase 3 study of CDK4 inhibitors in DDLS, and a strong international collaboration is key to conducting such studies, particularly in rare cancers. On a critical note, Dr. van der Graaf expressed concern that no patient-reported outcomes were measured after 120 patients, including those in previous studies, were treated on palbociclib and abemaciclib. Given that the toxicities of the CDK4 inhibitors are quite different, she recommended including patient-reported outcomes in future studies using validated health-related quality-of-life instruments.

SOURCE: Dickson MA, et al. J Clin Oncol 37, 2019 (suppl; abstr 11004)

The study was sponsored by Memorial Sloan Kettering Cancer Center, with the study collaborator, Eli Lilly and Company.

Dr. Dickson disclosed research funding from Lilly, the company that provided the study drug. Dr. van der Graaf had no relevant relationships to disclose. Abstract coauthors had consulting/advisory roles or research funding from various companies, including Lilly.

nab-Sirolimus Provides Benefits in Advanced Malignant PEComa

In a prospective phase 2 study of nab-sirolimus in advanced malignant perivascular epithelioid cell tumor (PEComa), the mTOR inhibitor achieved an objective response rate (ORR) of 42% with an acceptable safety profile, despite using relatively high doses of nab-sirolimus compared to other mTOR inhibitors. Activation of the mTOR pathway is common in PEComa, and earlier case reports had indicated substantial clinical benefit with mTOR inhibitor treatment. nab-Sirolimus (ABI-009) is a novel intravenous mTOR inhibitor consisting of nanoparticles of albumin-bound sirolimus. It has significantly higher anti-tumor activity than oral mTOR inhibitors and greater mTOR target suppression at an equal dose. Andrew J. Wagner, MD, PhD, of the Dana-Farber Cancer Institute in Boston, presented the findings of AMPECT (NCT02494570)—Advanced Malignant PEComa Trial—at ASCO.

Results

The drug was well tolerated, with toxicities similar to those of oral mTOR inhibitors. Treatment-related adverse events (TRAEs) occurring in 25% or more of patients were mostly grade 1 or 2 toxicities. Hematologic TRAEs included anemia (47%) and thrombocytopenia (32%) of any grade. Nonhematologic events of any grade included stomatitis/ mucositis (74%), dermatitis/rash (65%), fatigue (59%), nausea (47%), and diarrhea (38%), among others. A few grade 3 events occurred on study, most notably stomatitis/mucositis (18%). Severe adverse events (SAEs) were also uncommon, occurring in 7 of 34 patients (21%). Pneumonitis is common in orally administered mTOR inhibitors; 6 patients (18%) treated with nab-sirolimus had grade 1 or 2 pneumonitis.

Of the 31 evaluable patients, 13 (42%) had an objective response, all of which were partial responses (PR). Eleven (35%) had stable disease and 7 (23%) had progressive disease. The disease control rate, consisting of PR and stable disease, was 77%. The median duration of response had not been reached as of the data cutoff on May 10, 2019. At that time, it was 6.2 months (range, 1.5 to 27.7+). The median time to response was 1.4 months and the median progression-free survival (PFS) was 8.4 months. The PFS rate at 6 months was 61%. Three patients had received treatment for over a year and another 3 patients for more than 2 years.

Correlation with biomarkers

Of the 25 patients who had tissue suitable for next-generation sequencing, 9 had TSC2 mutations, 5 had TSC1 mutations, and 11 had neither mutation. Strikingly, 9 of 9 patients with TSC2 mutations developed a PR, while only 1 with a TSC1 mutation responded. One patient with no TSC1/2 mutation also responded and 2 patients with unknown mutational status responded. The investigators also analyzed pS6 status by immunohistochemistry—pS6 is a marker of mTOR hyperactivity. Twenty- five patient samples were available for analysis. Eight of 8 patients who were negative for pS6 staining did not have a response, while 10 of 17 (59%) who were pS6-positive had a PR.

In the discussion that followed, Winette van der Graaf, MD, of the Netherlands Cancer Institute in Amsterdam, noted that this study showed that biomarkers can be used for patient selection, although TSC2 mutations are not uniquely linked with response. She indicated a comparator with sirolimus would have been of great interest.

SOURCE: Wagner AJ, et al. J Clin Oncol 37, 2019 (suppl; abstr 11005).

The study was sponsored by Aadi Bioscience, Inc., and funded in part by a grant from the FDA Office of Orphan Products Development (OOPD).

Disclosures relevant to this presentation include contininstitutional research funding from Aadi Bioscience for Dr. Wagner and a few other abstract coauthors. Several coauthors are employed by Aadi Bioscience and have stock or other ownership interests. Dr. van der Graaf had nothing to disclose.

Cabozantinib Achieves Disease Control in GIST

The phase 2 EORTC 1317 trial, known as CaboGIST (NCT02216578), met its primary endpoint of progression-free survival (PFS) at 12 weeks in patients with metastatic gastrointestinal stromal tumor (GIST) treated with the tyrosine kinase inhibitor (TKI) cabozantinib. Twenty-four (58.5%) of the 41 patients in the primary study population, and 30 (60%) of the entire 50-patient population, were progression-free at 12 weeks. The study needed 21 patients to be progression- free for cabozantinib to warrant further exploration in GIST patients.

This investigator-initiated study had as its primary objective assessment of the safety and activity of cabozantinib in patients with metastatic GIST who had progressed on imatinib and sunitinib. The patients could not have been exposed to other KIT- or PDGFR-directed TKIs, such as regorafenib. Secondary objectives included the assessment of cabozantinib in different mutational subtypes of GIST. Patients received cabozantinib tablets once daily until they experienced no further clinical benefit or became intolerant to the drug or chose to discontinue therapy. Fifty patients started treatment between February 2017 and August 2018. All were evaluable for the primary endpoint, and one-third of patients contininstitutional cabozantinib treatment as of the database cutoff in January 2019.

Results

Patients were a median age of 63 years. Virtually all patients (92%) had prior surgery and only 8% had prior radiotherapy. The daily cabozantinib dose was a median 47.2 mg and duration of treatment was a median 20.4 weeks. No patient discontinued treatment due to toxicity, but 88% discontinued due to disease progression.

Safety signals were the same as for other indications in which cabozantinib is used. Almost all patients (94%) had at least 1 treatment-related adverse event of grades 1‐4, including diarrhea (74%), palmar-plantar erythrodysesthesia (58%), fatigue (46%), and hypertension (46%), which are typical of treatment with cabozantinib. Hematologic toxicities in this trial were clinically irrelevant, according to the investigators, consisting of small numbers of grades 2‐3 anemia, lymphopenia, white blood cell count abnormality, and neutropenia. Biochemical abnormalities included grades 3 and 4 hypophosphatemia, increased grades 3 and 4 gamma-glutamyl transferase, grade 3 hyponatremia, and grade 3 hypokalemia, in 8% or more of patients.

Overall survival was a median 14.4 months, with 16 patients still on treatment at the time of data cutoff. Twenty- four patients were progression-free at week 12, satisfying the study decision rule for clinical benefit. Median duration of PFS was 6.0 months. Seven patients (14%) achieved a confirmed partial response (PR) and 33 (66%) achieved stable disease (SD). Nine patients had progressive disease as their best response, 3 of whom had some clinical benefit. Forty patients (80%) experienced a clinical benefit of disease control (PR + SD).

An analysis of the relationship of genotype, duration, and RECIST response showed objective responses in patients with primary exon 11 mutations, with exon 9 mutations, and with exon 17 mutations, and in 2 patients without any known mutational information at the time of the presentation. Patients with stable disease were spread across all mutational subsets in the trial. The investigators suggested the definitive role of MET and AXL inhibition in GIST be assessed further in future clinical trials.

SOURCE: Schöffski P, et al. J Clin Oncol 37, 2019 (suppl; abstr 11006).

The study was sponsored by the European Organization for Research and Treatment of Cancer (EORTC).

Presenting author, Patrick Schöffski, MD, of KU Leuven and Leuven Cancer Institute in Belgium, disclosed institutional relationships with multiple pharmaceutical companies for consulting and research funding, including research funding from Exelixis, the developer of cabozantinib. No other abstract coauthor disclosed a relationship with Exelixis.

Larotectinib Effective in TRK Fusion Cancers

Pediatric patients with tropomyosin receptor kinase (TRK) fusions involving NTRK1, NTRK2, and NTRK3 genes had a high response rate with durable responses and a favorable safety profile when treated with larotrectinib, according to a presentation at ASCO. In this pediatric subset of children and adolescents from the SCOUT and NAVIGATE studies, the overall response rate (ORR) was 94%, with a 35% complete response (CR), 59% partial response (PR), and 6% stable disease as of the data cutoff at the end of July 2018.

Investigators enrolled 38 children and adolescents younger than 18 years from the SCOUT (NCT02637687) and NAVIGATE (NCT02576431) studies of larotrectinib who had non-central nervous system (CNS) TRK fusion cancers. Not all patients had the recommended phase 2 dose, Dr. van Tilburg pointed out, but most did. Hence, 29 of the 38 patients received the 100 mg/m² twice-daily, phase 2 dose until progression, withdrawal, or unacceptable toxicity.

Patients were young, with a median age of 2.3 years (range, 0.1 to 14.0 years). Almost two-thirds (61%) had prior surgery, 11% had prior radiotherapy, and 68% had prior systemic therapy. For 12 patients, larotrectinib was their first systemic therapy. The predominant tumor types were infantile fibrosarcoma (47%) and other soft tissue sarcoma (42%). And 47% of patients had NTRK3 fusions with ETV6, most of which were infantile fibrosarcoma.

Efficacy

Thirty-four patients were evaluable, and 32 had a reduction in tumor size, for an ORR of 94%, CR of 35%, and PR of 59%. Two patients with infantile fibrosarcoma had pathologic CRs—after treatment, no fibroid tissue in the tumors could be found. Median time to response was 1.8 months, median duration of treatment was 10.24 months, and 33 of 38 patients (87%) remained on treatment or underwent surgery with curative intent. As of the data cutoff of July 30, 2018, the secondary endpoints were not yet reached. However, 84% of responders were estimated to have a response duration of a year or more, and progression-free and overall survival looked very promising, according to Dr. van Tilburg.

Adverse events were primarily grades 1 and 2. The grades 3 and 4 treatment-related adverse events were quite few and consisted of increased alanine aminotransferase, decreased neutrophil count, and nausea. Longer follow-up of the patient safety profile is required, particularly since NTRK has multiple roles in neurodevelopment. The investigators recommended that routine testing for NTRK gene fusions in pediatric patients with cancer be conducted in appropriate clinical contexts.

In a discussion after the presentation, Daniel Alexander Morgenstern, MB BChir, PhD, of Great Ormond Street Hospital, London, UK, said that in many ways, the NTRK inhibitors have become the new poster child for precision oncology in pediatrics because of “these really spectacular results” with larotrectinib [and entrectinib]. One of the questions he raised regarding larotrectinib was the issue of CNS penetration, since patients with CNS cancer were not enrolled in the trial and preclinical data suggest limited CNS penetration for larotrectinib.

SOURCE: van Tilburg CM, et al. J Clin Oncol 37, 2019 (suppl; abstr 10010).

The studies were funded by Loxo Oncology, Inc., and Bayer AG.

Disclosures relevant to this presentation include consulting or advisory roles for Bayer for Drs. van Tilburg and Morgenstern. A few coauthors also had consulting/advisory roles or research funding from various companies, including Loxo and Bayer.

Behind Olaratumab's Phase 3 Disappointment

ANNOUNCE, the phase 3 trial designed to confirm the clinical benefit of olaratumab in patients with advanced soft tissue sarcoma (STS), failed to meet its primary endpoint of overall survival (OS) in all STS histologies and the leiomyosarcoma population. The previous phase 1b/2 signal-finding study of olaratumab had achieved an unprecedented improvement in OS, and the US Food and Drug Administration (FDA) awarded olaratumab accelerated approval in October 2016. By December 2018, olaratumab received additional accelerated, conditional, and full approvals in more than 40 countries worldwide. William D. Tap, MD, chief of the Sarcoma Medical Oncology Service at Memorial Sloan Kettering Cancer Center in New York, presented the phase 3 results and provided some explanations for the findings during the plenary session at ASCO.

ANNOUNCE (NCT02451943), which was designed and enrolled prior to olaratumab receiving accelerated approval, opened in September 2015 and completed accrual 10 months later in July 2016. Investigators randomized and treated 509 patients with advanced STS not amenable to curative therapy, 258 patients in the olaratumab-doxorubicin arm and 251 in the placebo-doxorubicin arm. Most patients (46%) had leiomyosarcoma, followed by liposarcoma (18%), pleomorphic sarcoma (13%), and 24% of the patient population had 26 unique histologies. Three-quarters of the patients had no prior systemic therapy.

Results

As of the data cutoff on December 5, 2018, there were no survival differences in the intention-to-treat population, in the total STS population nor in the leiomyosarcoma subpopulation, with olaratumab-doxorubicin compared to placebo-doxorubicin. For the total STS population, median OS with olaratumab- doxorubicin was 20.4 months and with placebo-doxorubicin 19.7 months. “This is the highest survival rate described to date in any phase 3 sarcoma study,” Dr. Tap said. “It is of particular interest as ANNOUNCE did not mandate treatment in the first line.” In the leiomyosarcoma population, median OS was 21.6 months with olaratumab and 21.9 months with placebo. The secondary endpoints of progression-free survival (PFS), overall response rate, and disease control rate did not favor olaratumab either.

Investigators are examining the relationship between PDGFRα expression and OS in ANNOUNCE. PDGFRα-positive tumors tended to do worse with olaratumab than PDGFRα-negative tumors. The investigators noticed a 6-month difference in OS between these populations favoring PDGFRα-negative tumors. Additional biomarker analyses are ongoing.

A large and concerted effort is underway, Dr. Tap said, to understand the results of the ANNOUNCE study alone and in context with the phase 1b/2 study. “There are no noted discrepancies in study conduct or data integrity which could explain these findings or the differences between the two studies.”

Possible explanations

The designs of the phase 1b/2 and phase 3 studies had some important differences. The phase 1b/2 study was a small, open-label, US-centric study (10 sites) that did not include a placebo or subtype- specified analyses. Its primary endpoint was PFS, it did not have a loading dose of olaratumab, and it specified the timing of dexrazoxane administration after 300 mg/m2 of doxorubicin.

ANNOUNCE, on the other hand, was a large (n=509), international (110 study sites), double-blind, placebo-controlled trial that had outcomes evaluated in STS and leiomyosarcoma. Its primary endpoint was OS, it had a loading dose of olaratumab of 20 mg/kg, and there was no restriction as to the timing of dexrazoxane administration.

Dr. Tap pointed out that in ANNOUNCE it was difficult to predict or control for factors that may have had an unanticipated influence on outcomes, such as albumin levels as a surrogate for disease burden and behavior of PDGFRα status. It is possible, he said, that olaratumab has no activity in STS and that the phase 1b/2 results were due to, among other things, the small sample size, numerous represented histologies with disparate clinical behavior, and the effect of subtype-specific therapies on overall survival, given subsequently or even by chance. On the other hand, it is also possible, he said, that olaratumab has some activity in STS, with outcomes being affected by the heterogeneity of the study populations, differences in trial design, and the performance of the ANNOUNCE control arm. Whatever the case, he said, accelerated approval allowed patients to have access to a potentially life-prolonging drug with little added toxicity.

Discussion

In the expert discussion following the presentation, Jaap Verweij, MD, PhD, of Erasmus University Medical Center in Rotterdam, The Netherlands, congratulated the investigators for performing the study at an unprecedented pace. He commented that lumping STS subtypes together is problematic, as different histological subtypes behave as though they are different diseases. Small numbers of each tumor subtype and subtypes with slow tumor growth can impact trial outcomes. In the phase 1b/2 and phase 3 trials, 26 different subtypes were represented in each study. Dr. Verweij pointed out this could have made a big difference in the phase 1b/2 study, in which there were only 66 patients in each arm.

It is striking to note, he said, that without exception, phase 2 randomized studies in STS involving doxorubicin consistently overestimated and wrongly predicted PFS in the subsequent phase 3 studies. And the situation is similar for OS. The results of the ANNOUNCE study are no exception, he added. “Taken together, these studies indicate that phase 2 studies in soft tissue sarcomas, certainly those involving additions of drugs to doxorubicin, even if randomized, should be interpreted with great caution,” he said.

SOURCE: Tap WD, et al. J Clin Oncol 37, 2019 (suppl; abstr LBA3)

The study was sponsored by Eli Lilly and Company.

Dr. Tap reported research funding from Lilly and Dr. Verweij had nothing to report related to this study. Abstract coauthors disclosed numerous financial relationships, including consulting/advisory roles and/or research funding from Lilly, and several were employed by Lilly.

Addition of Temozolomide May Improve Outcomes in RMS

Investigators from the European Pediatric Soft Tissue Sarcoma Study Group (EpSSG) found that the addition of temozolomide (T) to vincristine and irinotecan (VI) may improve outcomes in adults and children with relapsed or refractory rhabdomyosarcoma (RMS). Principal investigator of the study, Anne Sophie Defachelles, MD, pediatric oncologist at the Centre Oscar Lambret in Lille, France, presented the results on behalf of the EpSSG.

The international, randomized (1:1), open-label, phase 2 trial (VIT-0910; NCT01355445) was conducted at 37 centers in 5 countries. Patients ages 6 months to 50 years with RMS were eligible. They could not have had prior irinotecan or temozolomide. A 2015 protocol amendment limited enrollment to patients at relapse and increased the enrollment goal by 40 patients. After the 2015 amendment, patients with refractory disease were no longer eligible.

From January 2012 to April 2018, investigators enrolled 120 patients, 60 on each arm. Two patients in the VI arm were not treated. Patients were a median age of 10.5 years in the VI arm and 12 years in the VIT arm, 92% (VI) and 87% (VIT) had relapsed disease, 8% (VI) and 13% (VIT) had refractory disease, and 55% (VI) and 68% (VIT) had metastatic disease at study entry.

Results

Patients achieved an OR rate of 44% (VIT) and 31% (VI) for the whole population, one-sided P value <.0001. The adjusted odds ratio for the whole population was 0.50, P=.09. PFS was 4.7 months (VIT) and 3.2 months (VI), “a nearly significant reduction in the risk of progression,” Dr. Defachelles noted. Median OS was 15.0 months (VIT) and 10.3 months (VI), which amounted to “a large and significant reduction in the risk of death,” she said. The adjusted hazard ratio was 0.55, P=.006.

Adverse events of grade 3 or higher were more frequent in the VIT arm, with hematologic toxicity the most frequent (81% for VIT, 59% for VI), followed by gastrointestinal adverse events. “VIT was significantly more toxic than VI,” Dr. Defachelles observed, “but the toxicity was manageable.”

“VIT is now the standard treatment in Europe for relapsed rhabdomyosarcoma and will be the control arm in the multiarm, multistage RMS study for relapsed patients,” she said.

SOURCE: Defachelles AS, et al. J Clin Oncol 37, 2019 (suppl; abstr 10000)

The study was sponsored by Centre Oscar Lambret and SFCE (Société Française de Lutte contre les Cancers et Lucémies de l’Enfant et de l’Adolescent) served as collaborator.

Drs. Defachelles and Wagner had no relationships to disclose. A few coauthors had advisory/consulting or speaker roles for various commercial interests, including two for Merck (temozolomide).

Pazopanib Increases Pathologic Necrosis Rates in STS

Pazopanib added to a regimen of preoperative chemoradiation in non-rhabdomyosarcoma soft tissue sarcoma (NRSTS) significantly increased the rate of near-complete pathologic response in both children and adults with intermediate or high-risk disease. Pazopanib, a multitargeted receptor tyrosine kinase inhibitor, works in multiple signaling pathways involved in tumorigenesis— VEGFR-1, -2, -3, PDGFRα/β, and c-kit. A phase 3 study demonstrated significant improvement in progression-free survival (PFS) in advanced STS patients and was the basis for its approval in the US and elsewhere for treatment of this patient population. Preclinical data suggest synergy between pazopanib and cytotoxic chemotherapy, forming the rationale for the current trial with neoadjuvant pazopanib added to chemoradiation.

According to the investigators, the trial (ARST1321) is the first ever collaborative study codeveloped, written, and conducted by pediatric (Children’s Oncology Group) and adult (NRG Oncology) cancer cooperative groups (NCT02180867). Aaron R. Weiss, MD, of the Maine Medical Center in Portland and study cochair, presented the data for the chemotherapy arms at ASCO. The primary objectives of the study were to determine the feasibility of preoperative chemoradiation with or without pazopanib and to compare the rates of complete pathologic response in patients receiving radiation or chemoradiation with or without pazopanib. Pathologic necrosis rates of 90% or better have been found to be predictive of outcome in STS.

Results

As of the June 30, 2018, cutoff, 81 patients were enrolled on the chemotherapy arms: 42 in the pazopanib plus chemoradiation arm and 39 in the chemoradiation-only arm. Sixty-one percent of all patients were 18 years or older, and the median age was 20.3 years. Most patients (73%) did not have metastatic disease, and the major histologies represented were synovial sarcoma (49%) and undifferentiated pleomorphic sarcoma (25%).

At week 13, patients in the pazopanib arm showed significant improvement, with 14 (58%) of those evaluated having pathologic necrosis of at least 90%, compared with 4 (22%) in the chemoradiation-only arm (P=.02). The study was closed to further accrual.

Eighteen patients were not evaluable for pathologic response and 21 were pending pathologic evaluation at week 13. Radiographic response rates were not statistically significant on either arm. No complete responses (CR) were achieved in the pazopanib arm, but 14 patients (52%) achieved a partial response (PR) and 12 (44%) had stable disease (SD). In the chemoradiation-only arm, 2 patients (8%) achieved a CR, 12 (50%) a PR, and 8 (33%) SD. Fifteen patients in each arm were not evaluated for radiographic response.

The pazopanib arm experienced more febrile neutropenia and myelotoxicity during induction and continuation phases than the chemoradiation-only arm. In general, investigators indicated pazopanib combined with chemoradiation was well tolerated and no unexpected toxicities arose during the trial.

In the post-presentation discussion, Dr. Raphael E. Pollock, MD, PhD, of The Ohio State University, called it a tremendous challenge to interdigitate primary local therapies in systemic approaches, particularly in the neoadjuvant context. He pointed out that in an earlier study, a 95% to 100% necrosis level was needed to achieve a significant positive impact on outcomes and perhaps a subsequent prospective trial could determine the best level. He questioned whether the availability of only 60% of patient responses could affect the conclusions and whether the high number of toxicities (73.8% grade 3/4 with pazopanib) might be too high to consider the treatment for most patients, given the intensity of the regimen.

SOURCE: Weiss AR, et al. J Clin Oncol 37, 2019 (suppl; abstr 11002)

The study was sponsored by the National Cancer Institute.

Drs. Weiss and Pollock had no relationships with commercial interests to disclose. A few investigators disclosed advisory, consulting, or research roles with pharmaceutical companies, including one who received institutional research funding from Novartis (pazopanib).

Gemcitabine Plus Pazopanib a Potential Alternative in STS

In a phase 2 study of gemcitabine with pazopanib (G+P) or gemcitabine with docetaxel (G+D), investigators concluded the combination with pazopanib can be considered an alternative to that with docetaxel in select patients with advanced soft tissue sarcoma (STS). They reported similar progression-free survival (PFS) and rate of toxicity for the two regimens. Neeta Somaiah, MD, of the University of Texas MD Anderson Cancer Center in Houston, presented the findings of the investigator-initiated effort (NCT01593748) at ASCO.

The investigators enrolled 90 patients, 45 in each arm. Patients were a mean age of 56 years, and there was no difference in age or gender distribution between the arms. Patients with leiomyosarcoma (31% overall) or prior pelvic radiation (11% overall) were similar between the arms. The overall response rate using RECIST 1.1 criteria was partial response (PR) in 8 of 44 evaluable patients (18%) in the G+D arm and 5 of 43 evaluable patients (12%) in the G+P arm. Stable disease (SD) was observed in 21 patients (48%) in the G+D arm and 24 patients (56%) in the G+P arm. This amounted to a clinical benefit rate (PR + SD) of 66% and 68% for the G+D and G+P arms, respectively (Fisher’s exact test, P>.99). The median PFS was 4.1 months on both arms and the difference in median overall survival— 15.9 months in the G+D arm and 12.4 months in the G+P arm—was not statistically significant.

Adverse events (AEs) of grade 3 or higher occurred in 19.9% of patients on G+D and 20.6% on G+P. Serious AEs occurred in 33% (G+D) and 22% (G+P). Dose reductions were necessary in 80% of patients on G+P and doses were held in 93%. Dr. Somaiah explained that this may have been because the starting dose of gemcitabine and pazopanib (1000 mg/m² of gemcitabine on days 1 and 8 and 800 mg of pazopanib) was “probably higher than what we should have started at.” The rate of doses held was also higher in the pazopanib arm (93%) compared with the docetaxel arm (58%). This was likely because pazopanib was a daily dosing, so if there was a toxicity it was more likely to be held than docetaxel, she observed. Grade 3 or higher toxicities occurring in 5% or more of patients in either arm consisted generally of cytopenias and fatigue. The G+P arm experienced a high amount of neutropenia, most likely because this arm did not receive granulocyte-colony stimulating factor (GCSF) support, as opposed to the G+D arm.

Dr. Somaiah pointed out that the 12% response rate for the G+P combination is similar to what has been previously presented and higher than single-agent gemcitabine or pazopanib, but not higher than the G+D combination. The PFS of 4.1 months was less than anticipated, she added, but it was similar on both arms. The investigators believe the G+P combination warrants further exploration.

SOURCE: Somaiah N, et al. J Clin Oncol 37, 2019 (suppl; abstr 11008)

The study was sponsored by the Medical University of South Carolina, with Novartis as collaborator.

Dr. Somaiah disclosed Advisory Board roles for Blueprint, Deciphera, and Bayer. Abstract coauthors disclosed advisory/consulting roles or research funding from various commercial interests, including Novartis (pazopanib) and Pfizer (gemcitabine).

rEECur Trial Finding Optimal Chemotherapy Regimen for Ewing Sarcoma

Interim results of the first and largest randomized trial in patients with refractory or recurrent Ewing sarcoma (ES), the rEECur trial, are guiding the way to finding the optimal chemotherapy regimen to treat the disease. Until now, there has been little prospective evidence and no randomized data to guide treatment choices in relapsed or refractory patients, and hence no real standard of care, according to the presentation at ASCO. Several molecularly targeted therapies are emerging, and they require a standardized chemotherapy backbone against which they can be tested.

Results

Two hundred twenty patients 4 years or older and younger than 50 years with recurrent or refractory histologically confirmed ES of bone or soft tissue were randomized to receive GD (n=72) or TC, IT, or IFOS (n=148). Sixty-two GD patients and 123 TC/IT/IFOS patients were included in the primary outcome analysis. Patients were predominantly male (70%), with a median age of 19 years (range, 4 to 49). About two-thirds (67.3%) were post-pubertal. Most patients (85%) were primary refractory or experienced their first disease recurrence, and 89% had measurable disease.

Investigators assessed the primary outcome of objective response after 4 cycles of therapy and found 11% of patients treated with GD responded compared to 24% in the other 3 arms combined. When they subjected the data to Bayesian analysis, there was a 25% chance that the response rate in the GD arm was better than the response in Arm A, a 2% chance that it was better than Arm B, and a 3% chance that it was better than Arm C. Because this study was still blinded at the time of the presentation, investigators didn’t know which regimen constituted which arm. The probability that response favored GD, however, was low.

The investigators observed no surprising safety findings. Eighty-five percent of all patients experienced at least 1 adverse event. Most frequent grade 3‐5 events consisted of pneumonitis (50%, 60%), neutropenic fever (17%, 25%), and diarrhea (0, 12%) in GD and the combined 3 arms, respectively. Grade 3 events in the GD arm were lower than in the other 3 arms combined. There was 1 toxic death attributed to neutropenic sepsis in 1 of the 3 blinded arms.

Median progression-free survival (PFS) for all patients was approximately 5 months. Bayesian analysis suggested there was a low probability that GD was more effective than the other 3 arms: a 22% chance that GD was better than Arm A, a 3% chance that it was better than Arm B, and a 7% chance that it was better than Arm C. Bayesian analysis also suggested there was a probability that OS favored GD. Because the trial directs only the first 4 or 6 cycles of treatment and the patients receive more treatment after trial-directed therapy, investigators were not fully able to interpret this.

Data suggested GD is a less effective regimen than the other 3 regimens both by objective response rate and PFS, so GD has been dropped from the study. Investigators already had more than 75 evaluable patients in each of the 3 arms for the second interim analysis to take place. In a discussion following the presentation, Jayesh Desai, FRACP, of Peter MacCallum Cancer Centre in Melbourne, Australia, called this study a potentially practice-changing trial at this early stage, noting that the GD combination will be de-prioritized in practice based on these results.

SOURCE: McCabe MG, et al. J Clin Oncol 37, 2019 (suppl; abstr 11007)

The rEECur trial is sponsored by the University of Birmingham (UK) and received funding from the European Union’s Seventh Framework Programme under a grant agreement.

Dr. McCabe disclosed no conflicts of interest. Other authors disclosed consulting, advisory roles, or research funding from numerous pharmaceutical companies, including Lilly (gemcitabine) and Pfizer (irinotecan). Dr. Desai disclosed a consulting/advisory role and institutional research funding from Lilly.

Abemaciclib Meets Primary Endpoint in Phase 2 Trial of DDLS

The newer and more potent CDK4 inhibitor, abemaciclib, met its primary endpoint in the investigator-initiated, single-center, single-arm, phase 2 trial in patients with advanced progressive dedifferentiated liposarcoma (DDLS). Twenty-two patients (76%) achieved progression-free survival (PFS) at 12 weeks for a median PFS of 30 weeks. A subset of patients experienced prolonged clinical benefit, remaining on study with stable disease for over 900 days. The study (NCT02846987) was conducted at Memorial Sloan Kettering Cancer Center (MSKCC) in New York and Mark A. Dickson, MD, presented the results at ASCO.

Results

Thirty patients, 29 evaluable, with metastatic or recurrent DDLS were enrolled and treated with abemaciclib 200 mg orally twice daily between August 2016 and October 2018. Data cutoff for the presentation was the first week of May 2019. Patients were a median of 62 years, 60% were male, and half had no prior systemic treatment. Prior systemic treatments for those previously treated included doxorubicin, olaratumab, gemcitabine, docetaxel, ifosfamide, eribulin, and trabectedin. For 87%, the primary tumor was in their abdomen or retroperitoneum.

Toxicity was as expected with this class of agent, according to the investigators. The most common grades 2 and 3 toxicities, respectively, possibly related to the study drug, occurring in more than 1 patient included anemia (70%, 37%), thrombocytopenia (13%, 13%), neutropenia (43%, 17%), and lymphocyte count decreased (23%, 23%). Very few of these adverse events were grade 4—none for anemia, and 3% each for thrombocytopenia, neutropenia, and lymphocyte count decreased. Diarrhea of grades 2 and 3 occurred in 27% and 7% of patients, respectively, and was managed well with loperamide.

In addition to reaching the primary endpoint of 15 patients or more achieving PFS at 12 weeks, 1 patient had a confirmed partial response (PR) and another an unconfirmed PR. At data cutoff, 11 patients remained on study with stable disease or PR. The investigators conducted correlative studies that indicated all patients had CDK4 and MDM2 amplification with no loss of retinoblastoma tumor suppressor. They observed an inverse correlation between CDK4 amplification and PFS—the higher the level of CDK4 amplification, the shorter the PFS. They also found additional genomic alterations, including JUN, GLI1, ARID1A, TERT, and ATRX. TERT amplification was also associated with shorter PFS. Based on these findings, the investigators believe a phase 3 study of abemaciclib in DDLS is warranted.

Winette van der Graaf, MD, PhD, of the Netherlands Cancer Institute in Amsterdam, in the discussion following the presentation, concurred that it is certainly time for a multicenter phase 3 study of CDK4 inhibitors in DDLS, and a strong international collaboration is key to conducting such studies, particularly in rare cancers. On a critical note, Dr. van der Graaf expressed concern that no patient-reported outcomes were measured after 120 patients, including those in previous studies, were treated on palbociclib and abemaciclib. Given that the toxicities of the CDK4 inhibitors are quite different, she recommended including patient-reported outcomes in future studies using validated health-related quality-of-life instruments.

SOURCE: Dickson MA, et al. J Clin Oncol 37, 2019 (suppl; abstr 11004)

The study was sponsored by Memorial Sloan Kettering Cancer Center, with the study collaborator, Eli Lilly and Company.

Dr. Dickson disclosed research funding from Lilly, the company that provided the study drug. Dr. van der Graaf had no relevant relationships to disclose. Abstract coauthors had consulting/advisory roles or research funding from various companies, including Lilly.

nab-Sirolimus Provides Benefits in Advanced Malignant PEComa

In a prospective phase 2 study of nab-sirolimus in advanced malignant perivascular epithelioid cell tumor (PEComa), the mTOR inhibitor achieved an objective response rate (ORR) of 42% with an acceptable safety profile, despite using relatively high doses of nab-sirolimus compared to other mTOR inhibitors. Activation of the mTOR pathway is common in PEComa, and earlier case reports had indicated substantial clinical benefit with mTOR inhibitor treatment. nab-Sirolimus (ABI-009) is a novel intravenous mTOR inhibitor consisting of nanoparticles of albumin-bound sirolimus. It has significantly higher anti-tumor activity than oral mTOR inhibitors and greater mTOR target suppression at an equal dose. Andrew J. Wagner, MD, PhD, of the Dana-Farber Cancer Institute in Boston, presented the findings of AMPECT (NCT02494570)—Advanced Malignant PEComa Trial—at ASCO.

Results

The drug was well tolerated, with toxicities similar to those of oral mTOR inhibitors. Treatment-related adverse events (TRAEs) occurring in 25% or more of patients were mostly grade 1 or 2 toxicities. Hematologic TRAEs included anemia (47%) and thrombocytopenia (32%) of any grade. Nonhematologic events of any grade included stomatitis/ mucositis (74%), dermatitis/rash (65%), fatigue (59%), nausea (47%), and diarrhea (38%), among others. A few grade 3 events occurred on study, most notably stomatitis/mucositis (18%). Severe adverse events (SAEs) were also uncommon, occurring in 7 of 34 patients (21%). Pneumonitis is common in orally administered mTOR inhibitors; 6 patients (18%) treated with nab-sirolimus had grade 1 or 2 pneumonitis.

Of the 31 evaluable patients, 13 (42%) had an objective response, all of which were partial responses (PR). Eleven (35%) had stable disease and 7 (23%) had progressive disease. The disease control rate, consisting of PR and stable disease, was 77%. The median duration of response had not been reached as of the data cutoff on May 10, 2019. At that time, it was 6.2 months (range, 1.5 to 27.7+). The median time to response was 1.4 months and the median progression-free survival (PFS) was 8.4 months. The PFS rate at 6 months was 61%. Three patients had received treatment for over a year and another 3 patients for more than 2 years.

Correlation with biomarkers

Of the 25 patients who had tissue suitable for next-generation sequencing, 9 had TSC2 mutations, 5 had TSC1 mutations, and 11 had neither mutation. Strikingly, 9 of 9 patients with TSC2 mutations developed a PR, while only 1 with a TSC1 mutation responded. One patient with no TSC1/2 mutation also responded and 2 patients with unknown mutational status responded. The investigators also analyzed pS6 status by immunohistochemistry—pS6 is a marker of mTOR hyperactivity. Twenty- five patient samples were available for analysis. Eight of 8 patients who were negative for pS6 staining did not have a response, while 10 of 17 (59%) who were pS6-positive had a PR.

In the discussion that followed, Winette van der Graaf, MD, of the Netherlands Cancer Institute in Amsterdam, noted that this study showed that biomarkers can be used for patient selection, although TSC2 mutations are not uniquely linked with response. She indicated a comparator with sirolimus would have been of great interest.

SOURCE: Wagner AJ, et al. J Clin Oncol 37, 2019 (suppl; abstr 11005).

The study was sponsored by Aadi Bioscience, Inc., and funded in part by a grant from the FDA Office of Orphan Products Development (OOPD).

Disclosures relevant to this presentation include contininstitutional research funding from Aadi Bioscience for Dr. Wagner and a few other abstract coauthors. Several coauthors are employed by Aadi Bioscience and have stock or other ownership interests. Dr. van der Graaf had nothing to disclose.

Cabozantinib Achieves Disease Control in GIST

The phase 2 EORTC 1317 trial, known as CaboGIST (NCT02216578), met its primary endpoint of progression-free survival (PFS) at 12 weeks in patients with metastatic gastrointestinal stromal tumor (GIST) treated with the tyrosine kinase inhibitor (TKI) cabozantinib. Twenty-four (58.5%) of the 41 patients in the primary study population, and 30 (60%) of the entire 50-patient population, were progression-free at 12 weeks. The study needed 21 patients to be progression- free for cabozantinib to warrant further exploration in GIST patients.

This investigator-initiated study had as its primary objective assessment of the safety and activity of cabozantinib in patients with metastatic GIST who had progressed on imatinib and sunitinib. The patients could not have been exposed to other KIT- or PDGFR-directed TKIs, such as regorafenib. Secondary objectives included the assessment of cabozantinib in different mutational subtypes of GIST. Patients received cabozantinib tablets once daily until they experienced no further clinical benefit or became intolerant to the drug or chose to discontinue therapy. Fifty patients started treatment between February 2017 and August 2018. All were evaluable for the primary endpoint, and one-third of patients contininstitutional cabozantinib treatment as of the database cutoff in January 2019.

Results

Patients were a median age of 63 years. Virtually all patients (92%) had prior surgery and only 8% had prior radiotherapy. The daily cabozantinib dose was a median 47.2 mg and duration of treatment was a median 20.4 weeks. No patient discontinued treatment due to toxicity, but 88% discontinued due to disease progression.

Safety signals were the same as for other indications in which cabozantinib is used. Almost all patients (94%) had at least 1 treatment-related adverse event of grades 1‐4, including diarrhea (74%), palmar-plantar erythrodysesthesia (58%), fatigue (46%), and hypertension (46%), which are typical of treatment with cabozantinib. Hematologic toxicities in this trial were clinically irrelevant, according to the investigators, consisting of small numbers of grades 2‐3 anemia, lymphopenia, white blood cell count abnormality, and neutropenia. Biochemical abnormalities included grades 3 and 4 hypophosphatemia, increased grades 3 and 4 gamma-glutamyl transferase, grade 3 hyponatremia, and grade 3 hypokalemia, in 8% or more of patients.

Overall survival was a median 14.4 months, with 16 patients still on treatment at the time of data cutoff. Twenty- four patients were progression-free at week 12, satisfying the study decision rule for clinical benefit. Median duration of PFS was 6.0 months. Seven patients (14%) achieved a confirmed partial response (PR) and 33 (66%) achieved stable disease (SD). Nine patients had progressive disease as their best response, 3 of whom had some clinical benefit. Forty patients (80%) experienced a clinical benefit of disease control (PR + SD).

An analysis of the relationship of genotype, duration, and RECIST response showed objective responses in patients with primary exon 11 mutations, with exon 9 mutations, and with exon 17 mutations, and in 2 patients without any known mutational information at the time of the presentation. Patients with stable disease were spread across all mutational subsets in the trial. The investigators suggested the definitive role of MET and AXL inhibition in GIST be assessed further in future clinical trials.

SOURCE: Schöffski P, et al. J Clin Oncol 37, 2019 (suppl; abstr 11006).

The study was sponsored by the European Organization for Research and Treatment of Cancer (EORTC).

Presenting author, Patrick Schöffski, MD, of KU Leuven and Leuven Cancer Institute in Belgium, disclosed institutional relationships with multiple pharmaceutical companies for consulting and research funding, including research funding from Exelixis, the developer of cabozantinib. No other abstract coauthor disclosed a relationship with Exelixis.

Larotectinib Effective in TRK Fusion Cancers

Pediatric patients with tropomyosin receptor kinase (TRK) fusions involving NTRK1, NTRK2, and NTRK3 genes had a high response rate with durable responses and a favorable safety profile when treated with larotrectinib, according to a presentation at ASCO. In this pediatric subset of children and adolescents from the SCOUT and NAVIGATE studies, the overall response rate (ORR) was 94%, with a 35% complete response (CR), 59% partial response (PR), and 6% stable disease as of the data cutoff at the end of July 2018.

Investigators enrolled 38 children and adolescents younger than 18 years from the SCOUT (NCT02637687) and NAVIGATE (NCT02576431) studies of larotrectinib who had non-central nervous system (CNS) TRK fusion cancers. Not all patients had the recommended phase 2 dose, Dr. van Tilburg pointed out, but most did. Hence, 29 of the 38 patients received the 100 mg/m² twice-daily, phase 2 dose until progression, withdrawal, or unacceptable toxicity.

Patients were young, with a median age of 2.3 years (range, 0.1 to 14.0 years). Almost two-thirds (61%) had prior surgery, 11% had prior radiotherapy, and 68% had prior systemic therapy. For 12 patients, larotrectinib was their first systemic therapy. The predominant tumor types were infantile fibrosarcoma (47%) and other soft tissue sarcoma (42%). And 47% of patients had NTRK3 fusions with ETV6, most of which were infantile fibrosarcoma.

Efficacy

Thirty-four patients were evaluable, and 32 had a reduction in tumor size, for an ORR of 94%, CR of 35%, and PR of 59%. Two patients with infantile fibrosarcoma had pathologic CRs—after treatment, no fibroid tissue in the tumors could be found. Median time to response was 1.8 months, median duration of treatment was 10.24 months, and 33 of 38 patients (87%) remained on treatment or underwent surgery with curative intent. As of the data cutoff of July 30, 2018, the secondary endpoints were not yet reached. However, 84% of responders were estimated to have a response duration of a year or more, and progression-free and overall survival looked very promising, according to Dr. van Tilburg.

Adverse events were primarily grades 1 and 2. The grades 3 and 4 treatment-related adverse events were quite few and consisted of increased alanine aminotransferase, decreased neutrophil count, and nausea. Longer follow-up of the patient safety profile is required, particularly since NTRK has multiple roles in neurodevelopment. The investigators recommended that routine testing for NTRK gene fusions in pediatric patients with cancer be conducted in appropriate clinical contexts.

In a discussion after the presentation, Daniel Alexander Morgenstern, MB BChir, PhD, of Great Ormond Street Hospital, London, UK, said that in many ways, the NTRK inhibitors have become the new poster child for precision oncology in pediatrics because of “these really spectacular results” with larotrectinib [and entrectinib]. One of the questions he raised regarding larotrectinib was the issue of CNS penetration, since patients with CNS cancer were not enrolled in the trial and preclinical data suggest limited CNS penetration for larotrectinib.

SOURCE: van Tilburg CM, et al. J Clin Oncol 37, 2019 (suppl; abstr 10010).

The studies were funded by Loxo Oncology, Inc., and Bayer AG.

Disclosures relevant to this presentation include consulting or advisory roles for Bayer for Drs. van Tilburg and Morgenstern. A few coauthors also had consulting/advisory roles or research funding from various companies, including Loxo and Bayer.

ATLANTA – Sarcomas of bone and soft tissues are considered to be “antigenically cold” tumors, with few identifiable mutations that may be susceptible to targeted therapies.

Some sarcoma subtypes such as osteosarcoma and rhabomyosarcoma, however, frequently express the human epidermal growth factor receptor 2 on tumor surfaces. Although HER2 expression in these tumors is at too low a level for HER2-targeted therapies such as trastuzumab (Herceptin), HER2 appears to be an opportunistic target for chimeric antigen receptor (CAR) T-cell therapy, according to Shoba Navai, MD, from Baylor College of Medicine, Houston.

In a video interview at the 2019 annual meeting of the American Association for Cancer Research, Dr. Navai describes her team’s early experience using a HER2-targeted CAR-T cell construct and preinfusion lymphodepletion in patients with advanced sarcomas.

Development of the CAR-T cell construct is supported by the Cancer Prevention & Research Institute of Texas, Stand Up to Cancer, the St. Baldrick’s Foundation, Cookies for Kids’ Cancer, Alex’s Lemonade Stand, and a grant from the National Institutes of Health. Dr. Navai reported having no disclosures.

ATLANTA – Sarcomas of bone and soft tissues are considered to be “antigenically cold” tumors, with few identifiable mutations that may be susceptible to targeted therapies.

Some sarcoma subtypes such as osteosarcoma and rhabomyosarcoma, however, frequently express the human epidermal growth factor receptor 2 on tumor surfaces. Although HER2 expression in these tumors is at too low a level for HER2-targeted therapies such as trastuzumab (Herceptin), HER2 appears to be an opportunistic target for chimeric antigen receptor (CAR) T-cell therapy, according to Shoba Navai, MD, from Baylor College of Medicine, Houston.

In a video interview at the 2019 annual meeting of the American Association for Cancer Research, Dr. Navai describes her team’s early experience using a HER2-targeted CAR-T cell construct and preinfusion lymphodepletion in patients with advanced sarcomas.

Development of the CAR-T cell construct is supported by the Cancer Prevention & Research Institute of Texas, Stand Up to Cancer, the St. Baldrick’s Foundation, Cookies for Kids’ Cancer, Alex’s Lemonade Stand, and a grant from the National Institutes of Health. Dr. Navai reported having no disclosures.

ATLANTA – Sarcomas of bone and soft tissues are considered to be “antigenically cold” tumors, with few identifiable mutations that may be susceptible to targeted therapies.

Some sarcoma subtypes such as osteosarcoma and rhabomyosarcoma, however, frequently express the human epidermal growth factor receptor 2 on tumor surfaces. Although HER2 expression in these tumors is at too low a level for HER2-targeted therapies such as trastuzumab (Herceptin), HER2 appears to be an opportunistic target for chimeric antigen receptor (CAR) T-cell therapy, according to Shoba Navai, MD, from Baylor College of Medicine, Houston.

In a video interview at the 2019 annual meeting of the American Association for Cancer Research, Dr. Navai describes her team’s early experience using a HER2-targeted CAR-T cell construct and preinfusion lymphodepletion in patients with advanced sarcomas.

Development of the CAR-T cell construct is supported by the Cancer Prevention & Research Institute of Texas, Stand Up to Cancer, the St. Baldrick’s Foundation, Cookies for Kids’ Cancer, Alex’s Lemonade Stand, and a grant from the National Institutes of Health. Dr. Navai reported having no disclosures.

CHICAGO – Six months of maintenance chemotherapy prolongs overall survival in youth with high-risk rhabdomyosarcoma, finds a phase 3 randomized controlled trial of the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG).

Rhabdomyosarcoma is a rare but very aggressive tumor, lead study author Gianni Bisogno, MD, PhD, a professor at the University Hospital of Padova, Italy, and chair of the EpSSG, noted in a press briefing at the annual meeting of the American Society of Clinical Oncology, where the findings were reported. Among pediatric patients who achieve complete response to standard therapy, “we know that after 1 or 2 years, one-third of these children relapse, and most of them die,” he said.

The EpSSG trial, which took about 10 years to conduct, enrolled 371 patients aged 0-21 years with high-risk rhabdomyosarcoma who had had a complete response to standard intensive therapy. They were randomized evenly to stop treatment or to receive 6 months of maintenance treatment consisting of low-dose vinorelbine and cyclophosphamide.

Results reported in the meeting’s plenary session showed that giving maintenance chemotherapy improved the 5-year overall survival rate by an absolute 12.8%, which translated to a near halving of the risk of death. And the maintenance regimen used was generally well tolerated.

“At the end of this long, not-easy study, we concluded that maintenance chemotherapy is an effective and well tolerated treatment for children with high-risk rhabdomyosarcoma,” Dr. Bisogno said.

Susan London/MDedge News

Susan London/MDedge News

Study details

Patients enrolled in the EpSSG trial had had a complete response to the standard intensive therapy used in Europe: high-dose chemotherapy (ifosfamide, vincristine, and actinomycin D, with or without doxorubicin), radiation therapy, and surgery.

The maintenance chemotherapy consisted of a combination of low-dose intravenous vinorelbine given weekly and oral cyclophosphamide given daily. The 6-month duration was somewhat arbitrary, according to Dr. Bisogno. “We had to start somewhere. So when we started, we decided to use 6 months because there was some evidence in the past for regimens that long. In our next European trial, we are going to test different kinds and durations of maintenance because this is very important.”

SOURCE: Bisogno et al. ASCO 2018 Abstract LBA2.

CHICAGO – Six months of maintenance chemotherapy prolongs overall survival in youth with high-risk rhabdomyosarcoma, finds a phase 3 randomized controlled trial of the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG).

Rhabdomyosarcoma is a rare but very aggressive tumor, lead study author Gianni Bisogno, MD, PhD, a professor at the University Hospital of Padova, Italy, and chair of the EpSSG, noted in a press briefing at the annual meeting of the American Society of Clinical Oncology, where the findings were reported. Among pediatric patients who achieve complete response to standard therapy, “we know that after 1 or 2 years, one-third of these children relapse, and most of them die,” he said.

The EpSSG trial, which took about 10 years to conduct, enrolled 371 patients aged 0-21 years with high-risk rhabdomyosarcoma who had had a complete response to standard intensive therapy. They were randomized evenly to stop treatment or to receive 6 months of maintenance treatment consisting of low-dose vinorelbine and cyclophosphamide.

Results reported in the meeting’s plenary session showed that giving maintenance chemotherapy improved the 5-year overall survival rate by an absolute 12.8%, which translated to a near halving of the risk of death. And the maintenance regimen used was generally well tolerated.

“At the end of this long, not-easy study, we concluded that maintenance chemotherapy is an effective and well tolerated treatment for children with high-risk rhabdomyosarcoma,” Dr. Bisogno said.

Susan London/MDedge News

Susan London/MDedge News

Study details

Patients enrolled in the EpSSG trial had had a complete response to the standard intensive therapy used in Europe: high-dose chemotherapy (ifosfamide, vincristine, and actinomycin D, with or without doxorubicin), radiation therapy, and surgery.

The maintenance chemotherapy consisted of a combination of low-dose intravenous vinorelbine given weekly and oral cyclophosphamide given daily. The 6-month duration was somewhat arbitrary, according to Dr. Bisogno. “We had to start somewhere. So when we started, we decided to use 6 months because there was some evidence in the past for regimens that long. In our next European trial, we are going to test different kinds and durations of maintenance because this is very important.”

SOURCE: Bisogno et al. ASCO 2018 Abstract LBA2.

CHICAGO – Six months of maintenance chemotherapy prolongs overall survival in youth with high-risk rhabdomyosarcoma, finds a phase 3 randomized controlled trial of the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG).

Rhabdomyosarcoma is a rare but very aggressive tumor, lead study author Gianni Bisogno, MD, PhD, a professor at the University Hospital of Padova, Italy, and chair of the EpSSG, noted in a press briefing at the annual meeting of the American Society of Clinical Oncology, where the findings were reported. Among pediatric patients who achieve complete response to standard therapy, “we know that after 1 or 2 years, one-third of these children relapse, and most of them die,” he said.

The EpSSG trial, which took about 10 years to conduct, enrolled 371 patients aged 0-21 years with high-risk rhabdomyosarcoma who had had a complete response to standard intensive therapy. They were randomized evenly to stop treatment or to receive 6 months of maintenance treatment consisting of low-dose vinorelbine and cyclophosphamide.

Results reported in the meeting’s plenary session showed that giving maintenance chemotherapy improved the 5-year overall survival rate by an absolute 12.8%, which translated to a near halving of the risk of death. And the maintenance regimen used was generally well tolerated.

“At the end of this long, not-easy study, we concluded that maintenance chemotherapy is an effective and well tolerated treatment for children with high-risk rhabdomyosarcoma,” Dr. Bisogno said.

Susan London/MDedge News

Susan London/MDedge News

Study details

Patients enrolled in the EpSSG trial had had a complete response to the standard intensive therapy used in Europe: high-dose chemotherapy (ifosfamide, vincristine, and actinomycin D, with or without doxorubicin), radiation therapy, and surgery.

The maintenance chemotherapy consisted of a combination of low-dose intravenous vinorelbine given weekly and oral cyclophosphamide given daily. The 6-month duration was somewhat arbitrary, according to Dr. Bisogno. “We had to start somewhere. So when we started, we decided to use 6 months because there was some evidence in the past for regimens that long. In our next European trial, we are going to test different kinds and durations of maintenance because this is very important.”

SOURCE: Bisogno et al. ASCO 2018 Abstract LBA2.

CHICAGO – Maintenance chemotherapy is life-prolonging for youth with high-risk rhabdomyosarcoma, finds a trial of 371 patients aged 0 to 21 years who had completed standard intensive therapy.

The 5-year rate of overall survival was 86.5% for those who received maintenance therapy with the combination of low-dose intravenous vinorelbine and oral cyclophosphamide, compared with 73.7% for those who did not, translating to a near halving of the risk of death (hazard ratio, 0.52; P = .0111). The regimen was well tolerated. The findings represent the first treatment advance for this rare cancer in 30 years.

In an interview at the annual meeting of the American Society of Clinical Oncology, lead study author Gianni Bisogno, MD, PhD, discussed the risk-benefit profile of maintenance chemotherapy and the practice-changing nature of the new data. Dr. Bisogno, a professor at the University Hospital of Padova in Italy and chair of the European Paediatric Soft tissue Sarcoma Study Group, also described plans for a new trial that will explore alternate maintenance schedules and collaboration with colleagues in North America to further improve pediatric rhabdomyosarcoma outcomes.
 

CHICAGO – Maintenance chemotherapy is life-prolonging for youth with high-risk rhabdomyosarcoma, finds a trial of 371 patients aged 0 to 21 years who had completed standard intensive therapy.

The 5-year rate of overall survival was 86.5% for those who received maintenance therapy with the combination of low-dose intravenous vinorelbine and oral cyclophosphamide, compared with 73.7% for those who did not, translating to a near halving of the risk of death (hazard ratio, 0.52; P = .0111). The regimen was well tolerated. The findings represent the first treatment advance for this rare cancer in 30 years.

In an interview at the annual meeting of the American Society of Clinical Oncology, lead study author Gianni Bisogno, MD, PhD, discussed the risk-benefit profile of maintenance chemotherapy and the practice-changing nature of the new data. Dr. Bisogno, a professor at the University Hospital of Padova in Italy and chair of the European Paediatric Soft tissue Sarcoma Study Group, also described plans for a new trial that will explore alternate maintenance schedules and collaboration with colleagues in North America to further improve pediatric rhabdomyosarcoma outcomes.
 

CHICAGO – Maintenance chemotherapy is life-prolonging for youth with high-risk rhabdomyosarcoma, finds a trial of 371 patients aged 0 to 21 years who had completed standard intensive therapy.

The 5-year rate of overall survival was 86.5% for those who received maintenance therapy with the combination of low-dose intravenous vinorelbine and oral cyclophosphamide, compared with 73.7% for those who did not, translating to a near halving of the risk of death (hazard ratio, 0.52; P = .0111). The regimen was well tolerated. The findings represent the first treatment advance for this rare cancer in 30 years.

In an interview at the annual meeting of the American Society of Clinical Oncology, lead study author Gianni Bisogno, MD, PhD, discussed the risk-benefit profile of maintenance chemotherapy and the practice-changing nature of the new data. Dr. Bisogno, a professor at the University Hospital of Padova in Italy and chair of the European Paediatric Soft tissue Sarcoma Study Group, also described plans for a new trial that will explore alternate maintenance schedules and collaboration with colleagues in North America to further improve pediatric rhabdomyosarcoma outcomes.
 

Sarcoma dominance in uterine carcinosarcomas was associated with decreased survival among women with stages I-IV uterine carcinosarcomas who underwent primary surgery, according to Dr Koji Matsuo, MD, PhD, of the Keck School of Medicine, University of Southern California, Los Angeles, and his colleagues.

The researchers additionally found that adding radiotherapy to chemotherapy may be an effective postoperative strategy for these patients.

Uterine carcinosarcomas are rare, high-grade endometrial cancers that represent 5% of all endometrial cancers. Sarcoma dominance was defined as having more than a 50% sarcoma component in the uterine tumor. In this study, the sarcoma component was grouped as homologous (endometrial stromal sarcoma, leiomyosarcoma, fibrosarcoma, and undifferentiated sarcoma) or heterologous (rhabdomyosarcoma, osteosarcoma, chondrosarcoma, and liposarcoma) types

Among 1,192 cases of uterine carcinosarcomas identified in a secondary analysis of a multicenter retrospective study, 906 cases were available for histopathology slide review. Of those, 889 cases had evaluation for sarcoma dominance. The most common group was homologous sarcoma without sarcoma dominance (39.5%), followed by heterologous sarcoma with sarcoma dominance (21.3%), homologous sarcoma with sarcoma dominance (19.7%) and heterologous sarcoma with sarcoma non-dominance (19.6%), they reported in a study published online in Surgical Oncology https://doi.org/10.1016/j.suronc.2018.05.017

On univariate analysis, sarcoma dominance was associated with decreased progression-free survival (PFS) and cause-specific survival (CSS) in homologous cases (P less than 0.05) but not in heterologous cases. On multivariate models, both homologous and heterologous SD patterns remained independent prognostic factors for decreased PFS (adjusted-hazard ratio [HR] ranges: homologous/dominance 1.35-1.69, and heterologous/dominance 1.47-1.64) and CSS (adjusted-HR ranges: 1.52-1.84 and 1.66-1.81, respectively) compared to homologous/non-dominance (all, P less than 0.05).

In women with stage I-III disease, and tumors with sarcoma dominance, adding radiotherapy to chemotherapy was associated with improved PFS (adjusted-HR: homologous/dominance 0.49, and heterologous/dominance 0.45) and CSS (0.36 and 0.31, respectively) compared to chemotherapy alone (all, P less than 0.05); This association was not observed in women with tumors that lacked sarcoma dominance (all, P greater than 0.05), the researchers said.

Sarcoma dominance in uterine carcinosarcomas was associated with decreased survival among women with stages I-IV uterine carcinosarcomas who underwent primary surgery, according to Dr Koji Matsuo, MD, PhD, of the Keck School of Medicine, University of Southern California, Los Angeles, and his colleagues.

The researchers additionally found that adding radiotherapy to chemotherapy may be an effective postoperative strategy for these patients.

Uterine carcinosarcomas are rare, high-grade endometrial cancers that represent 5% of all endometrial cancers. Sarcoma dominance was defined as having more than a 50% sarcoma component in the uterine tumor. In this study, the sarcoma component was grouped as homologous (endometrial stromal sarcoma, leiomyosarcoma, fibrosarcoma, and undifferentiated sarcoma) or heterologous (rhabdomyosarcoma, osteosarcoma, chondrosarcoma, and liposarcoma) types

Among 1,192 cases of uterine carcinosarcomas identified in a secondary analysis of a multicenter retrospective study, 906 cases were available for histopathology slide review. Of those, 889 cases had evaluation for sarcoma dominance. The most common group was homologous sarcoma without sarcoma dominance (39.5%), followed by heterologous sarcoma with sarcoma dominance (21.3%), homologous sarcoma with sarcoma dominance (19.7%) and heterologous sarcoma with sarcoma non-dominance (19.6%), they reported in a study published online in Surgical Oncology https://doi.org/10.1016/j.suronc.2018.05.017

On univariate analysis, sarcoma dominance was associated with decreased progression-free survival (PFS) and cause-specific survival (CSS) in homologous cases (P less than 0.05) but not in heterologous cases. On multivariate models, both homologous and heterologous SD patterns remained independent prognostic factors for decreased PFS (adjusted-hazard ratio [HR] ranges: homologous/dominance 1.35-1.69, and heterologous/dominance 1.47-1.64) and CSS (adjusted-HR ranges: 1.52-1.84 and 1.66-1.81, respectively) compared to homologous/non-dominance (all, P less than 0.05).

In women with stage I-III disease, and tumors with sarcoma dominance, adding radiotherapy to chemotherapy was associated with improved PFS (adjusted-HR: homologous/dominance 0.49, and heterologous/dominance 0.45) and CSS (0.36 and 0.31, respectively) compared to chemotherapy alone (all, P less than 0.05); This association was not observed in women with tumors that lacked sarcoma dominance (all, P greater than 0.05), the researchers said.

Sarcoma dominance in uterine carcinosarcomas was associated with decreased survival among women with stages I-IV uterine carcinosarcomas who underwent primary surgery, according to Dr Koji Matsuo, MD, PhD, of the Keck School of Medicine, University of Southern California, Los Angeles, and his colleagues.

The researchers additionally found that adding radiotherapy to chemotherapy may be an effective postoperative strategy for these patients.

Uterine carcinosarcomas are rare, high-grade endometrial cancers that represent 5% of all endometrial cancers. Sarcoma dominance was defined as having more than a 50% sarcoma component in the uterine tumor. In this study, the sarcoma component was grouped as homologous (endometrial stromal sarcoma, leiomyosarcoma, fibrosarcoma, and undifferentiated sarcoma) or heterologous (rhabdomyosarcoma, osteosarcoma, chondrosarcoma, and liposarcoma) types

Among 1,192 cases of uterine carcinosarcomas identified in a secondary analysis of a multicenter retrospective study, 906 cases were available for histopathology slide review. Of those, 889 cases had evaluation for sarcoma dominance. The most common group was homologous sarcoma without sarcoma dominance (39.5%), followed by heterologous sarcoma with sarcoma dominance (21.3%), homologous sarcoma with sarcoma dominance (19.7%) and heterologous sarcoma with sarcoma non-dominance (19.6%), they reported in a study published online in Surgical Oncology https://doi.org/10.1016/j.suronc.2018.05.017

On univariate analysis, sarcoma dominance was associated with decreased progression-free survival (PFS) and cause-specific survival (CSS) in homologous cases (P less than 0.05) but not in heterologous cases. On multivariate models, both homologous and heterologous SD patterns remained independent prognostic factors for decreased PFS (adjusted-hazard ratio [HR] ranges: homologous/dominance 1.35-1.69, and heterologous/dominance 1.47-1.64) and CSS (adjusted-HR ranges: 1.52-1.84 and 1.66-1.81, respectively) compared to homologous/non-dominance (all, P less than 0.05).

In women with stage I-III disease, and tumors with sarcoma dominance, adding radiotherapy to chemotherapy was associated with improved PFS (adjusted-HR: homologous/dominance 0.49, and heterologous/dominance 0.45) and CSS (0.36 and 0.31, respectively) compared to chemotherapy alone (all, P less than 0.05); This association was not observed in women with tumors that lacked sarcoma dominance (all, P greater than 0.05), the researchers said.

Introduction

Tumor lysis syndrome (TLS) is a life-threatening oncologic emergency that results when massive cell breakdown occurs either spontaneously or in response to cytotoxic chemotherapy. TLS is characterized by metabolic derangements, including hyperkalemia and hyperphosphatemia, secondary to the release of intracellular components into the systemic circulatory system. In addition, purine degradation can lead to hyperuricemia, and precipitation of calcium phosphate can result in hypocalcemia. Lactate dehydrogenase (LDH) levels are often elevated, especially in higher risk patients; however, this finding is not a specific marker for TLS.

TLS more commonly occurs in patients with rapidly proliferating hematological malignancies, such as acute leukemias with a high white blood cell count and Burkitt’s lymphoma, and is a relatively rare event in patients with solid malignancies.^1-3 It is even more rare in patients with tumor recurrence.

There are few reported cases of TLS in children with solid malignancies. To our knowledge, only one case of TLS has previously been reported in a pediatric patient with abdominal rhabdomyosarcoma. We report the second such case, and what we believe to be the only reported case of TLS occurring in a pediatric patient with recurrence of a solid tumor.

Case Description

A 15-year-old male from Saudi Arabia presented to our hospital with confirmed stage IV abdominal rhabdomyosarcoma and lung metastases diagnosed in 2012. His initial treatment consisted of complete surgical resection, lung irradiation, and chemotherapy with intercalating cycles of ifosfamide/etoposide and vincristine/doxorubicin/cyclophosphamide, as per the COG-ARST0431 high-risk sarcoma protocol (NCT00354744). He completed treatment without any reported TLS in Saudi Arabia in June 2014. He had no residual tumor at the end of therapy, but six months later he was found to have an abdominal recurrence and started treatment with single-agent topotecan chemotherapy. He experienced worsening abdominal distention, pain, and difficulty voiding, prompting his family to seek further treatment options abroad.

The patient was admitted to our hospital in March 2015. Despite being severely malnourished, he was in stable condition. He was noted to have a markedly enlarged, firm, distended abdomen with dilated veins, abdominal and lower back pain, lower extremity pitting edema, and difficulty urinating.

Initial laboratory findings were unremarkable except for elevated levels of BUN (29 mg/dL), creatinine (1.69 mg/dL), and phosphorus (5.6 mg/dL). MRI revealed a large pelvic mass measuring 15.3 x 15.2 x 21.3 centimeters in transverse, anterior-posterior, and craniocaudal dimensions, respectively; with concomitant severe bilateral hydroureternephrosis (FIGURE 1).

FIGURE 1. Sagittal (A) and Axial (B) T2-weighted MR images of the pelvis (prior to initiating therapy) demonstrating a large heterogeneous mass occupying the entire pelvis. There is evidence of edema involving the soft tissues of the perineum (long arrow) and a large associated hydrocele (short arrow).

Three days following admission, the patient’s urine output decreased and his creatinine level rose rapidly. His worsening abdominal distention was attributed to growing tumor bulk and obstructive nephropathy. He required emergency placement of bilateral nephrostomy tubes. Urine output subsequently improved; although, serum creatinine remained persistently elevated.

Given his worsening condition, chemotherapy was begun three days after nephrostomy tube placement with vinorelbine, cyclophosphamide, and temsirolimus, as per COG-ARST0921 (NCT01222715), at renal-adjusted doses. Laboratory studies approximately 24 hours after chemotherapy initiation demonstrated the presence of TLS (TABLE 1). Potassium level was at the upper end of normal at 4.9 mmol/L, calcium level was decreased to 7.1 mg/dL, phosphorus level elevated to 12 mg/dL, uric acid level was markedly elevated to 19.5 mg/dL, and LDH elevated to 662 unit/L. A dose of 0.15 mg/kg of rasburicase was immediately given with a second dose repeated 14 hours later, after which the uric acid level decreased to less than 0.5 mg/dL. Sevelamer, sodium polystyrene, calcium carbonate, and magnesium gluconate were also administered to treat other electrolyte imbalances. The patient remained at clinical baseline throughout, and the TLS laboratory derangements normalized by three days after the TLS diagnosis; LDH level normalized after one week. The patient continued with chemotherapy, per protocol, with no further TLS-related complications. Over subsequent weeks, his tumor continued to shrink dramatically. Pain related to intra-abdominal compression, lower extremity edema, and difficulty voiding resolved.

Discussion

A literature search was performed using Pubmed/Medline and Scopus from 1950 to July 2016 using key words “TLS,” “tumor lysis syndrome,” “pediatric tumor lysis syndrome,” “tumor lysis syndrome in solid malignancies,” “recurrence,” “solid tumor,” “sarcoma,” “rhabdomyosarcoma,” and their combinations. The references of relevant articles were reviewed. Baeksgaard and Sorensen,³ and Vodopivec, et al⁴ provide an organized review of reported cases of TLS in solid tumors until 2002 and 2011 respectively; their articles are supported by the 2014 literature review by Mirrakhimov, et al.¹ Excluding our case, 13 cases of TLS have been described in pediatric patients with solid tumors, with only one occurring in patient with abdominal rhabdomyosarcoma⁵. Patients’ ages ranged from 2 days to 23 years; the cases are summarized in the following table (TABLE 2). To our knowledge, ours is the first case of TLS reported in association with a pediatric solid tumor recurrence.

It is important to note that the three reported cases of disseminated rhabdomyosarcoma^6,7 were initially believed to be hematologic malignancies because of their presentation with lymphadenopathy, metastases to the bone marrow, and spontaneous onset of TLS. Rhabdomyosarcoma with bone marrow involvement without an obvious primary tumor is easily confused with acute leukemia, particularly of the lymphoblastic type.¹² However, this disseminated-hematologic presentation of rhabdomyosarcoma differs from the solid abdominal-pelvic tumor, which we describe.

Cairo and Bishop¹³ categorize patients as either laboratory TLS, depicted by metabolic abnormalities alone, or clinical TLS, occurring when laboratory imbalances lead to significant, life-threatening clinical manifestations. Hyperkalemia may lead to cardiac arrhythmias such as torsades de pointes and cardiac arrest. Obstructive nephropathy can occur from the precipitation of calcium phosphate or uric acid crystals in the renal tubules. Hypocalcemia may cause neuromuscular irritability including tetany, convulsions, and altered mental status.^{13, 14}The 2015 “Guidelines for the management of tumour lysis syndrome in adults and children with haematological malignancies on behalf of the British Committee for Standards in Haematology”⁴ state there are well-recognized risk factors for the development of TLS including, but not limited to, high tumor burden, tumors with rapid cell turnover, and pre-existing renal impairment. Cairo and Bishop, on behalf of the TLS expert panel consensus of 2010², classify patients as having low-risk disease (LRD), intermediate-risk disease (IRD), or high-risk disease (HRD) based on the risk factors and type of malignancy. All patients with solid tumors are classified into LRD, unless the tumors are bulky or sensitive to chemotherapy, mentioning specifically that neuroblastomas, germ-cell tumors and small cell lung cancers are classified as IRD. Cairo and Bishop take into account the risk factor of renal dysfunction/ involvement, which if present, increases the risk by one level. For example, if the patient has IRD and has renal dysfunction, risk increases to HRD². However, these guidelines do not mention or address the significance of recurrence in any kind of malignancy with regards to assessing risk for TLS.

The British Committee’s 2015 Guidelines for management of TLS in hematologic malignancies¹⁴ provide recommendations for treatment based on the patient’s risk classification (TABLE 3). Children with HRD are recommended to be treated prophylactically with a single dose of 0.2 mg/kg of rasburicase. Patients with IRD are recommended to be offered up to 7 days of allopurinol prophylaxis with increased hydration post initiation of treatment or until risk of TLS has resolved. Patients with LRD are recommended to be managed essentially with close observation. Patients with established TLS should receive rasburicase 0.2 mg/kg/day - duration to depend on clinical response. If the patient is receiving rasburicase, the addition of allopurinol is not recommended, as it has the potential to reduce the effectiveness of rasburicase. Further, rasburicase is to be avoided in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency¹⁴.

Our patient likely developed TLS because of a fast growing tumor that caused significant tumor burden and renal involvement, indicated by an elevated phosphorus level. Despite these risk factors, TLS was not anticipated in the case presented; therefore, a uric acid level was not collected at the time of admission. Review of the literature indicates that the incidence of TLS in a solid tumor recurrence is either unheard of, or is likely under-reported and truly unknown. Further, the TLS expert panel consensus of 2010², which provides guidelines on risk assessment for TLS, does not address the risk of TLS in a malignancy recurrence. The British Committee’s 2015 guidelines¹⁴ also do not address hyperuricemia prophylaxis in a solid tumor recurrence.

Our case presents a question regarding the degree of risk for the development of TLS in a solid tumor recurrence. If the guidelines had existed at the time of the case presentation and had been applied, our patient would likely be classified as having IRD because of his renal involvement. This classification would have lead to a different course of management when initiating chemotherapy, likely prevented laboratory TLS, and provided more cost effective treatment, as rasburicase is known to be expensive.

On the other hand, it can also be argued that our patient classifies as LRD, considering the rarity of TLS in a solid tumor recurrence, that the patient had no TLS complication with his initial course of therapy, and also had a normal LDH on admission. LDH is sometimes used to assess risk in hematological malignancies, although it is not used to make the diagnosis of TLS². However, with such an argument, it is assumed that the risk of TLS in a solid tumor malignancy recurrence, with no previous TLS complication, is less than the risk associated with a new-onset solid tumor malignancy when, truly, the actual risk is not known. Again, the question is raised of the degree of risk for the development of TLS in a case of a malignancy recurrence, and also in a pediatric patient with risk factors.

In our patient’s case, close observation allowed for prompt diagnosis, appropriate treatment of laboratory TLS, and prevented clinical symptoms from developing. However, a screening or baseline uric acid level may have lead to a more conservative approach towards hyperuricemia prophylaxis, similar to treating the patient as IRD. Therefore, we recommend that a screening or baseline uric acid level and LDH level be obtained when initiating chemotherapy, even in patients with LRD.

Our patient was never hyperkalemic, likely because of concomitant administration of furosemide in an attempt to improve his decreased urine output. Hyperuricemia dropped from 19.5 mg/dL to less than 0.5 mg/dL within 24 hours, following two doses of 0.15 mg/kg of rasburicase, confirming the efficacy of this therapy in cases of established TLS, as is recommended by the British Committee’s 2015 guidelines.¹⁴

Conclusion

TLS is a relatively rare event in patients with solid malignancies and even more rare in a tumor recurrence. While there is only one previously reported case of TLS occurring in a pediatric patient with abdominal rhabdomyosarcoma, there are not any reported cases to date of TLS occurring in pediatric solid tumor recurrence. This may be because the incidence is truly rare or because cases may be under-reported. Thus, a question is raised regarding the risk for TLS in a solid tumor recurrence, and moreover in a pediatric patient with pre-existing risk factors, such as renal involvement.

TLS remains a life-threatening emergency that can be prevented and reversed if a high index of suspicion is maintained. We recommend all patients with malignancies receiving chemotherapy, especially those with risk factors, have a baseline or screening uric acid and LDH level drawn, as part of the assessment and risk-stratification for TLS which should always be performed. TSJ

Correspondence

References

1. Mirrakhimov AE, Ali AM, Khan M, et al. Tumor lysis syndrome in solid tumors: an up to date review of the literature. Rare Tumors. 2014;6:68-74.

2. Cairo MS, Bertrand C, Reiter A, et al. Recommendation for the evaluation of risk and prophylaxis of tumour lysis syndrome (TLS) in adults and children with malignant diseases: an expert TLS panel consensus. Br J Haematol. 2010;149:578-586.

3. Baeksgaard L, Sorensen JB. Acute tumor lysis syndrome in solid tumors – a case report and review of the literature. Cancer Chemother Pharmacol. 2003;51:187-192.

4. Vodopivec D, Rubio J, Fornoni A, et al. An unusual presentation of tumor lysis syndrome in a patient with advanced gastric adenocarcinoma: case report and literature review. Case Rep Med. 2012;2012:1-12.

5. Khan J, Broadbent VA. Tumor lysis syndrome complicating treatment of widespread metastatic abdominal rhabdomyosarcoma. Pediatr Hematol Oncol. 1993;10:151-155.

6. Bien E, Maciejka-Kapuscinka L, Niedzwiecki M, et al. Childhood rhabdomyosarcoma metastatic to bone marrow presenting with disseminated intravascular coagulation and acute tumour lysis syndrome: review of the literature apropos of two cases. Clin Exp Metastasis. 2010;27:399-407.

7. Patiroglu T, Isik B, Unal E, et al. Cranial metastatic alveolar rhabdomyosarcoma mimicking hematological malignancy in an adolescent boy. Childs Nerv Syst. 2014;30:1737-1741.

8. Hain RD, Rayner L, Weitzman S, et al. Acute tumour lysis syndrome complicating treatment of stage IVS neuroblastoma in infants under six months old. Med Pediatr Oncol. 1994;23:136-139.

9. Kushner BH, LaQuaglia MP, Modak S, et al. Tumor lysis syndrome, neuroblastoma, and correlation between serum lactate dehydrogenase levels and MYCN-amplification. Med Pediatr Oncol. 2003;41:80-82.

10. Bercovitz RS, Greffe BS, Hunger SP. Acute tumor lysis syndrome in a 7-month-old with hepatoblastoma. Curr Opin Pediatr. 2010;22:113-116.

11. Lobe TE, Karkera MS, Custer MD, et al. Fatal refractory hyperkalemia due to tumor lysis during primary resection for hepatoblastoma. J Pediatr Surg. 1990;25:249-250.

12. Sandberg A, Stone J, Czarnecki L, et al. Hematologic Masquerade of Rhabdomyosarcoma. Am J Hematol. 2001;68:51-57

13. Cairo M, Bishop M. Tumour lysis syndrome: new therapeutic strategies and classification. Br J Haematol. 2004;127:3-11.

14. Jones G, Will A, Jackson GH, et al. Guidelines for the management of tumour lysis syndrome in adults and children with haematological malignancies on behalf of the British Committee for Standards in Haematology. Br J Haematol. 2015;169:661-671.

Introduction

Tumor lysis syndrome (TLS) is a life-threatening oncologic emergency that results when massive cell breakdown occurs either spontaneously or in response to cytotoxic chemotherapy. TLS is characterized by metabolic derangements, including hyperkalemia and hyperphosphatemia, secondary to the release of intracellular components into the systemic circulatory system. In addition, purine degradation can lead to hyperuricemia, and precipitation of calcium phosphate can result in hypocalcemia. Lactate dehydrogenase (LDH) levels are often elevated, especially in higher risk patients; however, this finding is not a specific marker for TLS.

TLS more commonly occurs in patients with rapidly proliferating hematological malignancies, such as acute leukemias with a high white blood cell count and Burkitt’s lymphoma, and is a relatively rare event in patients with solid malignancies.^1-3 It is even more rare in patients with tumor recurrence.

There are few reported cases of TLS in children with solid malignancies. To our knowledge, only one case of TLS has previously been reported in a pediatric patient with abdominal rhabdomyosarcoma. We report the second such case, and what we believe to be the only reported case of TLS occurring in a pediatric patient with recurrence of a solid tumor.

Case Description

A 15-year-old male from Saudi Arabia presented to our hospital with confirmed stage IV abdominal rhabdomyosarcoma and lung metastases diagnosed in 2012. His initial treatment consisted of complete surgical resection, lung irradiation, and chemotherapy with intercalating cycles of ifosfamide/etoposide and vincristine/doxorubicin/cyclophosphamide, as per the COG-ARST0431 high-risk sarcoma protocol (NCT00354744). He completed treatment without any reported TLS in Saudi Arabia in June 2014. He had no residual tumor at the end of therapy, but six months later he was found to have an abdominal recurrence and started treatment with single-agent topotecan chemotherapy. He experienced worsening abdominal distention, pain, and difficulty voiding, prompting his family to seek further treatment options abroad.

The patient was admitted to our hospital in March 2015. Despite being severely malnourished, he was in stable condition. He was noted to have a markedly enlarged, firm, distended abdomen with dilated veins, abdominal and lower back pain, lower extremity pitting edema, and difficulty urinating.

Initial laboratory findings were unremarkable except for elevated levels of BUN (29 mg/dL), creatinine (1.69 mg/dL), and phosphorus (5.6 mg/dL). MRI revealed a large pelvic mass measuring 15.3 x 15.2 x 21.3 centimeters in transverse, anterior-posterior, and craniocaudal dimensions, respectively; with concomitant severe bilateral hydroureternephrosis (FIGURE 1).

FIGURE 1. Sagittal (A) and Axial (B) T2-weighted MR images of the pelvis (prior to initiating therapy) demonstrating a large heterogeneous mass occupying the entire pelvis. There is evidence of edema involving the soft tissues of the perineum (long arrow) and a large associated hydrocele (short arrow).

Three days following admission, the patient’s urine output decreased and his creatinine level rose rapidly. His worsening abdominal distention was attributed to growing tumor bulk and obstructive nephropathy. He required emergency placement of bilateral nephrostomy tubes. Urine output subsequently improved; although, serum creatinine remained persistently elevated.

Given his worsening condition, chemotherapy was begun three days after nephrostomy tube placement with vinorelbine, cyclophosphamide, and temsirolimus, as per COG-ARST0921 (NCT01222715), at renal-adjusted doses. Laboratory studies approximately 24 hours after chemotherapy initiation demonstrated the presence of TLS (TABLE 1). Potassium level was at the upper end of normal at 4.9 mmol/L, calcium level was decreased to 7.1 mg/dL, phosphorus level elevated to 12 mg/dL, uric acid level was markedly elevated to 19.5 mg/dL, and LDH elevated to 662 unit/L. A dose of 0.15 mg/kg of rasburicase was immediately given with a second dose repeated 14 hours later, after which the uric acid level decreased to less than 0.5 mg/dL. Sevelamer, sodium polystyrene, calcium carbonate, and magnesium gluconate were also administered to treat other electrolyte imbalances. The patient remained at clinical baseline throughout, and the TLS laboratory derangements normalized by three days after the TLS diagnosis; LDH level normalized after one week. The patient continued with chemotherapy, per protocol, with no further TLS-related complications. Over subsequent weeks, his tumor continued to shrink dramatically. Pain related to intra-abdominal compression, lower extremity edema, and difficulty voiding resolved.

Discussion

A literature search was performed using Pubmed/Medline and Scopus from 1950 to July 2016 using key words “TLS,” “tumor lysis syndrome,” “pediatric tumor lysis syndrome,” “tumor lysis syndrome in solid malignancies,” “recurrence,” “solid tumor,” “sarcoma,” “rhabdomyosarcoma,” and their combinations. The references of relevant articles were reviewed. Baeksgaard and Sorensen,³ and Vodopivec, et al⁴ provide an organized review of reported cases of TLS in solid tumors until 2002 and 2011 respectively; their articles are supported by the 2014 literature review by Mirrakhimov, et al.¹ Excluding our case, 13 cases of TLS have been described in pediatric patients with solid tumors, with only one occurring in patient with abdominal rhabdomyosarcoma⁵. Patients’ ages ranged from 2 days to 23 years; the cases are summarized in the following table (TABLE 2). To our knowledge, ours is the first case of TLS reported in association with a pediatric solid tumor recurrence.

It is important to note that the three reported cases of disseminated rhabdomyosarcoma^6,7 were initially believed to be hematologic malignancies because of their presentation with lymphadenopathy, metastases to the bone marrow, and spontaneous onset of TLS. Rhabdomyosarcoma with bone marrow involvement without an obvious primary tumor is easily confused with acute leukemia, particularly of the lymphoblastic type.¹² However, this disseminated-hematologic presentation of rhabdomyosarcoma differs from the solid abdominal-pelvic tumor, which we describe.

Cairo and Bishop¹³ categorize patients as either laboratory TLS, depicted by metabolic abnormalities alone, or clinical TLS, occurring when laboratory imbalances lead to significant, life-threatening clinical manifestations. Hyperkalemia may lead to cardiac arrhythmias such as torsades de pointes and cardiac arrest. Obstructive nephropathy can occur from the precipitation of calcium phosphate or uric acid crystals in the renal tubules. Hypocalcemia may cause neuromuscular irritability including tetany, convulsions, and altered mental status.^{13, 14}The 2015 “Guidelines for the management of tumour lysis syndrome in adults and children with haematological malignancies on behalf of the British Committee for Standards in Haematology”⁴ state there are well-recognized risk factors for the development of TLS including, but not limited to, high tumor burden, tumors with rapid cell turnover, and pre-existing renal impairment. Cairo and Bishop, on behalf of the TLS expert panel consensus of 2010², classify patients as having low-risk disease (LRD), intermediate-risk disease (IRD), or high-risk disease (HRD) based on the risk factors and type of malignancy. All patients with solid tumors are classified into LRD, unless the tumors are bulky or sensitive to chemotherapy, mentioning specifically that neuroblastomas, germ-cell tumors and small cell lung cancers are classified as IRD. Cairo and Bishop take into account the risk factor of renal dysfunction/ involvement, which if present, increases the risk by one level. For example, if the patient has IRD and has renal dysfunction, risk increases to HRD². However, these guidelines do not mention or address the significance of recurrence in any kind of malignancy with regards to assessing risk for TLS.

The British Committee’s 2015 Guidelines for management of TLS in hematologic malignancies¹⁴ provide recommendations for treatment based on the patient’s risk classification (TABLE 3). Children with HRD are recommended to be treated prophylactically with a single dose of 0.2 mg/kg of rasburicase. Patients with IRD are recommended to be offered up to 7 days of allopurinol prophylaxis with increased hydration post initiation of treatment or until risk of TLS has resolved. Patients with LRD are recommended to be managed essentially with close observation. Patients with established TLS should receive rasburicase 0.2 mg/kg/day - duration to depend on clinical response. If the patient is receiving rasburicase, the addition of allopurinol is not recommended, as it has the potential to reduce the effectiveness of rasburicase. Further, rasburicase is to be avoided in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency¹⁴.

Our patient likely developed TLS because of a fast growing tumor that caused significant tumor burden and renal involvement, indicated by an elevated phosphorus level. Despite these risk factors, TLS was not anticipated in the case presented; therefore, a uric acid level was not collected at the time of admission. Review of the literature indicates that the incidence of TLS in a solid tumor recurrence is either unheard of, or is likely under-reported and truly unknown. Further, the TLS expert panel consensus of 2010², which provides guidelines on risk assessment for TLS, does not address the risk of TLS in a malignancy recurrence. The British Committee’s 2015 guidelines¹⁴ also do not address hyperuricemia prophylaxis in a solid tumor recurrence.

Our case presents a question regarding the degree of risk for the development of TLS in a solid tumor recurrence. If the guidelines had existed at the time of the case presentation and had been applied, our patient would likely be classified as having IRD because of his renal involvement. This classification would have lead to a different course of management when initiating chemotherapy, likely prevented laboratory TLS, and provided more cost effective treatment, as rasburicase is known to be expensive.

On the other hand, it can also be argued that our patient classifies as LRD, considering the rarity of TLS in a solid tumor recurrence, that the patient had no TLS complication with his initial course of therapy, and also had a normal LDH on admission. LDH is sometimes used to assess risk in hematological malignancies, although it is not used to make the diagnosis of TLS². However, with such an argument, it is assumed that the risk of TLS in a solid tumor malignancy recurrence, with no previous TLS complication, is less than the risk associated with a new-onset solid tumor malignancy when, truly, the actual risk is not known. Again, the question is raised of the degree of risk for the development of TLS in a case of a malignancy recurrence, and also in a pediatric patient with risk factors.

In our patient’s case, close observation allowed for prompt diagnosis, appropriate treatment of laboratory TLS, and prevented clinical symptoms from developing. However, a screening or baseline uric acid level may have lead to a more conservative approach towards hyperuricemia prophylaxis, similar to treating the patient as IRD. Therefore, we recommend that a screening or baseline uric acid level and LDH level be obtained when initiating chemotherapy, even in patients with LRD.

Our patient was never hyperkalemic, likely because of concomitant administration of furosemide in an attempt to improve his decreased urine output. Hyperuricemia dropped from 19.5 mg/dL to less than 0.5 mg/dL within 24 hours, following two doses of 0.15 mg/kg of rasburicase, confirming the efficacy of this therapy in cases of established TLS, as is recommended by the British Committee’s 2015 guidelines.¹⁴

Conclusion

TLS is a relatively rare event in patients with solid malignancies and even more rare in a tumor recurrence. While there is only one previously reported case of TLS occurring in a pediatric patient with abdominal rhabdomyosarcoma, there are not any reported cases to date of TLS occurring in pediatric solid tumor recurrence. This may be because the incidence is truly rare or because cases may be under-reported. Thus, a question is raised regarding the risk for TLS in a solid tumor recurrence, and moreover in a pediatric patient with pre-existing risk factors, such as renal involvement.

TLS remains a life-threatening emergency that can be prevented and reversed if a high index of suspicion is maintained. We recommend all patients with malignancies receiving chemotherapy, especially those with risk factors, have a baseline or screening uric acid and LDH level drawn, as part of the assessment and risk-stratification for TLS which should always be performed. TSJ

Correspondence

References

1. Mirrakhimov AE, Ali AM, Khan M, et al. Tumor lysis syndrome in solid tumors: an up to date review of the literature. Rare Tumors. 2014;6:68-74.

2. Cairo MS, Bertrand C, Reiter A, et al. Recommendation for the evaluation of risk and prophylaxis of tumour lysis syndrome (TLS) in adults and children with malignant diseases: an expert TLS panel consensus. Br J Haematol. 2010;149:578-586.

3. Baeksgaard L, Sorensen JB. Acute tumor lysis syndrome in solid tumors – a case report and review of the literature. Cancer Chemother Pharmacol. 2003;51:187-192.

4. Vodopivec D, Rubio J, Fornoni A, et al. An unusual presentation of tumor lysis syndrome in a patient with advanced gastric adenocarcinoma: case report and literature review. Case Rep Med. 2012;2012:1-12.

5. Khan J, Broadbent VA. Tumor lysis syndrome complicating treatment of widespread metastatic abdominal rhabdomyosarcoma. Pediatr Hematol Oncol. 1993;10:151-155.

6. Bien E, Maciejka-Kapuscinka L, Niedzwiecki M, et al. Childhood rhabdomyosarcoma metastatic to bone marrow presenting with disseminated intravascular coagulation and acute tumour lysis syndrome: review of the literature apropos of two cases. Clin Exp Metastasis. 2010;27:399-407.

7. Patiroglu T, Isik B, Unal E, et al. Cranial metastatic alveolar rhabdomyosarcoma mimicking hematological malignancy in an adolescent boy. Childs Nerv Syst. 2014;30:1737-1741.

8. Hain RD, Rayner L, Weitzman S, et al. Acute tumour lysis syndrome complicating treatment of stage IVS neuroblastoma in infants under six months old. Med Pediatr Oncol. 1994;23:136-139.

9. Kushner BH, LaQuaglia MP, Modak S, et al. Tumor lysis syndrome, neuroblastoma, and correlation between serum lactate dehydrogenase levels and MYCN-amplification. Med Pediatr Oncol. 2003;41:80-82.

10. Bercovitz RS, Greffe BS, Hunger SP. Acute tumor lysis syndrome in a 7-month-old with hepatoblastoma. Curr Opin Pediatr. 2010;22:113-116.

11. Lobe TE, Karkera MS, Custer MD, et al. Fatal refractory hyperkalemia due to tumor lysis during primary resection for hepatoblastoma. J Pediatr Surg. 1990;25:249-250.

12. Sandberg A, Stone J, Czarnecki L, et al. Hematologic Masquerade of Rhabdomyosarcoma. Am J Hematol. 2001;68:51-57

13. Cairo M, Bishop M. Tumour lysis syndrome: new therapeutic strategies and classification. Br J Haematol. 2004;127:3-11.

14. Jones G, Will A, Jackson GH, et al. Guidelines for the management of tumour lysis syndrome in adults and children with haematological malignancies on behalf of the British Committee for Standards in Haematology. Br J Haematol. 2015;169:661-671.

Introduction

Tumor lysis syndrome (TLS) is a life-threatening oncologic emergency that results when massive cell breakdown occurs either spontaneously or in response to cytotoxic chemotherapy. TLS is characterized by metabolic derangements, including hyperkalemia and hyperphosphatemia, secondary to the release of intracellular components into the systemic circulatory system. In addition, purine degradation can lead to hyperuricemia, and precipitation of calcium phosphate can result in hypocalcemia. Lactate dehydrogenase (LDH) levels are often elevated, especially in higher risk patients; however, this finding is not a specific marker for TLS.

TLS more commonly occurs in patients with rapidly proliferating hematological malignancies, such as acute leukemias with a high white blood cell count and Burkitt’s lymphoma, and is a relatively rare event in patients with solid malignancies.^1-3 It is even more rare in patients with tumor recurrence.

There are few reported cases of TLS in children with solid malignancies. To our knowledge, only one case of TLS has previously been reported in a pediatric patient with abdominal rhabdomyosarcoma. We report the second such case, and what we believe to be the only reported case of TLS occurring in a pediatric patient with recurrence of a solid tumor.

Case Description

A 15-year-old male from Saudi Arabia presented to our hospital with confirmed stage IV abdominal rhabdomyosarcoma and lung metastases diagnosed in 2012. His initial treatment consisted of complete surgical resection, lung irradiation, and chemotherapy with intercalating cycles of ifosfamide/etoposide and vincristine/doxorubicin/cyclophosphamide, as per the COG-ARST0431 high-risk sarcoma protocol (NCT00354744). He completed treatment without any reported TLS in Saudi Arabia in June 2014. He had no residual tumor at the end of therapy, but six months later he was found to have an abdominal recurrence and started treatment with single-agent topotecan chemotherapy. He experienced worsening abdominal distention, pain, and difficulty voiding, prompting his family to seek further treatment options abroad.

The patient was admitted to our hospital in March 2015. Despite being severely malnourished, he was in stable condition. He was noted to have a markedly enlarged, firm, distended abdomen with dilated veins, abdominal and lower back pain, lower extremity pitting edema, and difficulty urinating.

Initial laboratory findings were unremarkable except for elevated levels of BUN (29 mg/dL), creatinine (1.69 mg/dL), and phosphorus (5.6 mg/dL). MRI revealed a large pelvic mass measuring 15.3 x 15.2 x 21.3 centimeters in transverse, anterior-posterior, and craniocaudal dimensions, respectively; with concomitant severe bilateral hydroureternephrosis (FIGURE 1).

FIGURE 1. Sagittal (A) and Axial (B) T2-weighted MR images of the pelvis (prior to initiating therapy) demonstrating a large heterogeneous mass occupying the entire pelvis. There is evidence of edema involving the soft tissues of the perineum (long arrow) and a large associated hydrocele (short arrow).

Three days following admission, the patient’s urine output decreased and his creatinine level rose rapidly. His worsening abdominal distention was attributed to growing tumor bulk and obstructive nephropathy. He required emergency placement of bilateral nephrostomy tubes. Urine output subsequently improved; although, serum creatinine remained persistently elevated.

Given his worsening condition, chemotherapy was begun three days after nephrostomy tube placement with vinorelbine, cyclophosphamide, and temsirolimus, as per COG-ARST0921 (NCT01222715), at renal-adjusted doses. Laboratory studies approximately 24 hours after chemotherapy initiation demonstrated the presence of TLS (TABLE 1). Potassium level was at the upper end of normal at 4.9 mmol/L, calcium level was decreased to 7.1 mg/dL, phosphorus level elevated to 12 mg/dL, uric acid level was markedly elevated to 19.5 mg/dL, and LDH elevated to 662 unit/L. A dose of 0.15 mg/kg of rasburicase was immediately given with a second dose repeated 14 hours later, after which the uric acid level decreased to less than 0.5 mg/dL. Sevelamer, sodium polystyrene, calcium carbonate, and magnesium gluconate were also administered to treat other electrolyte imbalances. The patient remained at clinical baseline throughout, and the TLS laboratory derangements normalized by three days after the TLS diagnosis; LDH level normalized after one week. The patient continued with chemotherapy, per protocol, with no further TLS-related complications. Over subsequent weeks, his tumor continued to shrink dramatically. Pain related to intra-abdominal compression, lower extremity edema, and difficulty voiding resolved.

Discussion

A literature search was performed using Pubmed/Medline and Scopus from 1950 to July 2016 using key words “TLS,” “tumor lysis syndrome,” “pediatric tumor lysis syndrome,” “tumor lysis syndrome in solid malignancies,” “recurrence,” “solid tumor,” “sarcoma,” “rhabdomyosarcoma,” and their combinations. The references of relevant articles were reviewed. Baeksgaard and Sorensen,³ and Vodopivec, et al⁴ provide an organized review of reported cases of TLS in solid tumors until 2002 and 2011 respectively; their articles are supported by the 2014 literature review by Mirrakhimov, et al.¹ Excluding our case, 13 cases of TLS have been described in pediatric patients with solid tumors, with only one occurring in patient with abdominal rhabdomyosarcoma⁵. Patients’ ages ranged from 2 days to 23 years; the cases are summarized in the following table (TABLE 2). To our knowledge, ours is the first case of TLS reported in association with a pediatric solid tumor recurrence.

It is important to note that the three reported cases of disseminated rhabdomyosarcoma^6,7 were initially believed to be hematologic malignancies because of their presentation with lymphadenopathy, metastases to the bone marrow, and spontaneous onset of TLS. Rhabdomyosarcoma with bone marrow involvement without an obvious primary tumor is easily confused with acute leukemia, particularly of the lymphoblastic type.¹² However, this disseminated-hematologic presentation of rhabdomyosarcoma differs from the solid abdominal-pelvic tumor, which we describe.

Cairo and Bishop¹³ categorize patients as either laboratory TLS, depicted by metabolic abnormalities alone, or clinical TLS, occurring when laboratory imbalances lead to significant, life-threatening clinical manifestations. Hyperkalemia may lead to cardiac arrhythmias such as torsades de pointes and cardiac arrest. Obstructive nephropathy can occur from the precipitation of calcium phosphate or uric acid crystals in the renal tubules. Hypocalcemia may cause neuromuscular irritability including tetany, convulsions, and altered mental status.^{13, 14}The 2015 “Guidelines for the management of tumour lysis syndrome in adults and children with haematological malignancies on behalf of the British Committee for Standards in Haematology”⁴ state there are well-recognized risk factors for the development of TLS including, but not limited to, high tumor burden, tumors with rapid cell turnover, and pre-existing renal impairment. Cairo and Bishop, on behalf of the TLS expert panel consensus of 2010², classify patients as having low-risk disease (LRD), intermediate-risk disease (IRD), or high-risk disease (HRD) based on the risk factors and type of malignancy. All patients with solid tumors are classified into LRD, unless the tumors are bulky or sensitive to chemotherapy, mentioning specifically that neuroblastomas, germ-cell tumors and small cell lung cancers are classified as IRD. Cairo and Bishop take into account the risk factor of renal dysfunction/ involvement, which if present, increases the risk by one level. For example, if the patient has IRD and has renal dysfunction, risk increases to HRD². However, these guidelines do not mention or address the significance of recurrence in any kind of malignancy with regards to assessing risk for TLS.

The British Committee’s 2015 Guidelines for management of TLS in hematologic malignancies¹⁴ provide recommendations for treatment based on the patient’s risk classification (TABLE 3). Children with HRD are recommended to be treated prophylactically with a single dose of 0.2 mg/kg of rasburicase. Patients with IRD are recommended to be offered up to 7 days of allopurinol prophylaxis with increased hydration post initiation of treatment or until risk of TLS has resolved. Patients with LRD are recommended to be managed essentially with close observation. Patients with established TLS should receive rasburicase 0.2 mg/kg/day - duration to depend on clinical response. If the patient is receiving rasburicase, the addition of allopurinol is not recommended, as it has the potential to reduce the effectiveness of rasburicase. Further, rasburicase is to be avoided in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency¹⁴.

Our patient likely developed TLS because of a fast growing tumor that caused significant tumor burden and renal involvement, indicated by an elevated phosphorus level. Despite these risk factors, TLS was not anticipated in the case presented; therefore, a uric acid level was not collected at the time of admission. Review of the literature indicates that the incidence of TLS in a solid tumor recurrence is either unheard of, or is likely under-reported and truly unknown. Further, the TLS expert panel consensus of 2010², which provides guidelines on risk assessment for TLS, does not address the risk of TLS in a malignancy recurrence. The British Committee’s 2015 guidelines¹⁴ also do not address hyperuricemia prophylaxis in a solid tumor recurrence.

Our case presents a question regarding the degree of risk for the development of TLS in a solid tumor recurrence. If the guidelines had existed at the time of the case presentation and had been applied, our patient would likely be classified as having IRD because of his renal involvement. This classification would have lead to a different course of management when initiating chemotherapy, likely prevented laboratory TLS, and provided more cost effective treatment, as rasburicase is known to be expensive.

On the other hand, it can also be argued that our patient classifies as LRD, considering the rarity of TLS in a solid tumor recurrence, that the patient had no TLS complication with his initial course of therapy, and also had a normal LDH on admission. LDH is sometimes used to assess risk in hematological malignancies, although it is not used to make the diagnosis of TLS². However, with such an argument, it is assumed that the risk of TLS in a solid tumor malignancy recurrence, with no previous TLS complication, is less than the risk associated with a new-onset solid tumor malignancy when, truly, the actual risk is not known. Again, the question is raised of the degree of risk for the development of TLS in a case of a malignancy recurrence, and also in a pediatric patient with risk factors.

In our patient’s case, close observation allowed for prompt diagnosis, appropriate treatment of laboratory TLS, and prevented clinical symptoms from developing. However, a screening or baseline uric acid level may have lead to a more conservative approach towards hyperuricemia prophylaxis, similar to treating the patient as IRD. Therefore, we recommend that a screening or baseline uric acid level and LDH level be obtained when initiating chemotherapy, even in patients with LRD.

Our patient was never hyperkalemic, likely because of concomitant administration of furosemide in an attempt to improve his decreased urine output. Hyperuricemia dropped from 19.5 mg/dL to less than 0.5 mg/dL within 24 hours, following two doses of 0.15 mg/kg of rasburicase, confirming the efficacy of this therapy in cases of established TLS, as is recommended by the British Committee’s 2015 guidelines.¹⁴

Conclusion

TLS is a relatively rare event in patients with solid malignancies and even more rare in a tumor recurrence. While there is only one previously reported case of TLS occurring in a pediatric patient with abdominal rhabdomyosarcoma, there are not any reported cases to date of TLS occurring in pediatric solid tumor recurrence. This may be because the incidence is truly rare or because cases may be under-reported. Thus, a question is raised regarding the risk for TLS in a solid tumor recurrence, and moreover in a pediatric patient with pre-existing risk factors, such as renal involvement.

TLS remains a life-threatening emergency that can be prevented and reversed if a high index of suspicion is maintained. We recommend all patients with malignancies receiving chemotherapy, especially those with risk factors, have a baseline or screening uric acid and LDH level drawn, as part of the assessment and risk-stratification for TLS which should always be performed. TSJ

Correspondence

References

1. Mirrakhimov AE, Ali AM, Khan M, et al. Tumor lysis syndrome in solid tumors: an up to date review of the literature. Rare Tumors. 2014;6:68-74.

2. Cairo MS, Bertrand C, Reiter A, et al. Recommendation for the evaluation of risk and prophylaxis of tumour lysis syndrome (TLS) in adults and children with malignant diseases: an expert TLS panel consensus. Br J Haematol. 2010;149:578-586.

3. Baeksgaard L, Sorensen JB. Acute tumor lysis syndrome in solid tumors – a case report and review of the literature. Cancer Chemother Pharmacol. 2003;51:187-192.

4. Vodopivec D, Rubio J, Fornoni A, et al. An unusual presentation of tumor lysis syndrome in a patient with advanced gastric adenocarcinoma: case report and literature review. Case Rep Med. 2012;2012:1-12.

5. Khan J, Broadbent VA. Tumor lysis syndrome complicating treatment of widespread metastatic abdominal rhabdomyosarcoma. Pediatr Hematol Oncol. 1993;10:151-155.

6. Bien E, Maciejka-Kapuscinka L, Niedzwiecki M, et al. Childhood rhabdomyosarcoma metastatic to bone marrow presenting with disseminated intravascular coagulation and acute tumour lysis syndrome: review of the literature apropos of two cases. Clin Exp Metastasis. 2010;27:399-407.

7. Patiroglu T, Isik B, Unal E, et al. Cranial metastatic alveolar rhabdomyosarcoma mimicking hematological malignancy in an adolescent boy. Childs Nerv Syst. 2014;30:1737-1741.

8. Hain RD, Rayner L, Weitzman S, et al. Acute tumour lysis syndrome complicating treatment of stage IVS neuroblastoma in infants under six months old. Med Pediatr Oncol. 1994;23:136-139.

9. Kushner BH, LaQuaglia MP, Modak S, et al. Tumor lysis syndrome, neuroblastoma, and correlation between serum lactate dehydrogenase levels and MYCN-amplification. Med Pediatr Oncol. 2003;41:80-82.

10. Bercovitz RS, Greffe BS, Hunger SP. Acute tumor lysis syndrome in a 7-month-old with hepatoblastoma. Curr Opin Pediatr. 2010;22:113-116.

11. Lobe TE, Karkera MS, Custer MD, et al. Fatal refractory hyperkalemia due to tumor lysis during primary resection for hepatoblastoma. J Pediatr Surg. 1990;25:249-250.

12. Sandberg A, Stone J, Czarnecki L, et al. Hematologic Masquerade of Rhabdomyosarcoma. Am J Hematol. 2001;68:51-57

13. Cairo M, Bishop M. Tumour lysis syndrome: new therapeutic strategies and classification. Br J Haematol. 2004;127:3-11.

14. Jones G, Will A, Jackson GH, et al. Guidelines for the management of tumour lysis syndrome in adults and children with haematological malignancies on behalf of the British Committee for Standards in Haematology. Br J Haematol. 2015;169:661-671.

Introduction

Soft tissue sarcomas (STSs) are rare adult tumors, with 3.4 new cases per 100,000 persons or 12,310 expected new cases in 2016.¹ Sarcomas are a heterogeneous collection of tumors that affect fat, muscle, nerve, nerve sheath, vascular, and connective tissues. There are more than 50 histological subtypes that comprise this diverse category of tumors. Treatment varies by stage, with limb-sparing surgery representing the mainstay of curative-intent treatment. Radiation and chemotherapy may also be considered depending on the size, grade, and location of the tumor. Survival rates have been stagnant until recently, with a disease-specific survival hovering around 65%.¹ Given the complexity of these cases, all patients ideally should be evaluated and treated by a multidisciplinary team at an institution with extensive experience treating STS.²

Epidemiology and Classification

The most common STS subtypes are gastrointestinal stromal tumor (GIST), undifferentiate pleomorphic sarcoma (previously referred to as malignant fibrous histiocytoma), liposarcoma, leiomyosarcoma, synovial sarcoma, malignant peripheral nerve sheath tumor, rhabdomyosarcoma, and unclassified sarcoma.³ Liposarcoma is one of the most common subtypes, comprising 20% of all STSs; it is subdivided into well-differentiated/dedifferentiated liposarcomas, myxoid/round cell liposarcomas, and pleomorphic liposarcomas. Well-differentiated liposarcomas tend to occur in the retroperitoneum and limbs, while both myxoid and round cell as well as pleomorphic liposarcomas more commonly originate on the limbs. Histology varies based on subtype and ranges from mature-appearing adipocytes and fibroblasts to undifferentiated cells with minimal lipogenic differentiation.⁴

Leiomyosarcomas are smooth muscle tumors and are usually located in the retroperitoneum, but have also been associated with peripheral soft tissue and vasculature. Typical histology ranges from well-defined areas of spindle-shaped cells to poorly differentiated anaplastic spindle cells.^5,6 Synovial sarcomas are a distinct type of STS that can show epithelial differentiation and account for 5% of adult STSs. The extremities are the most common presenting location (90%).⁷

Rhabdomyosarcomas are skeletal muscle tumors and are further subdivided into embryonal, alveolar, and pleomorphic subtypes. Embryonal histology ranges from primitive mesenchymal-appearing cells to highly differentiated muscle cells. Alveolar rhabdomyosarcoma has the worst prognosis of the subtypes and consists of round cells with high nuclear-to-chromatin ratios that form “glandular-like” or “alveolar” spaces.⁸ Pleomorphic rhabdomyosarcomas are composed of rhabdomyoblasts that can affect many different locations, but most commonly present on the lower extremities.⁹

Malignant peripheral nerve sheath tumor (MPNST) comprises 5% to 10% of all STSs. These tumors are associated with neurofibromatosis type 1 (NF-1), with 25% to 50% of tumors occurring in NF-1 patients. Additionally, most patients have a truncating lesion in the NF1 gene on chromosome 17.¹⁰ Anghileri et al in their single institution analysis of 205 patients with MPNSTs found the 2 most common presenting sites were the trunk and extremities. Histologically, these tumors have dense fascicles of spindle cells.¹⁰

GISTs are the most common STS of the gastrointestinal (GI) tract. Previously, GISTs were classified as smooth muscle tumors and were not accounted for in the literature as a separate entity distinct from leiomyomas, leiomyoblastomas, and leiomyosarcomas.¹¹ GISTs are found throughout the GI tract: the most common sites are the stomach (60%) and small intestine (30%). Less common sites include duodenum (4%–5%), esophagus (1%), rectum (1%–2%), and appendix (< 0.2%).¹² GISTs can be spindle cell, epithelioid, or mesenchymal tumors. Immunohistochemically, GISTs are KIT (CD117) positive. Other cell markers that are also commonly positive include CD34 (60%–70%) and smooth muscle actin (SMA) (25%).¹¹ The majority of GISTs (80%) have an activating c-KIT gene mutation. The most common mutation site is exon 11, with less common c-KIT gene mutations also occurring at exon 9 or 13. Not all GISTs have KIT mutations. The second most common mutation is the PDGFRA mutation (5%–10% of GISTs).² A minority of GISTs are negative for both KIT and PDGFRA mutations. These tumors were previously called wild-type, but as the majority have either a succinate dehydrogenase (SDH) loss of function or loss of SDHB protein expression, they are now referred to as SDH-deficient GISTs.² GISTs vary in aggressiveness from incidental to aggressive. Typically, small intestine and rectal GISTs are more aggressive than gastric GISTs. Both size and mitotic rate help to predict the metastatic potential of the tumor. Tumors less than 2 cm in size and having a mitotic rate of less than 5 per 50 high-power fields (hpf) have the lowest risk of metastases, while tumors greater than 5 cm and with more than 5 mitoses per 50 hpf have the highest rates of metastases.¹²

Angiosarcomas are rare tumors comprising 4% of all STSs. Although they can occur in any site, the majority are cutaneous and occur most frequently in the head and neck regions. These tumors are either of vascular or lymphatic origin and are comprised of abnormal, pleomorphic, malignant endothelial cells. The most useful immunohistochemical markers include von Willebrand factor, CD31, and Ulex europaeus agglutinin 1. The majority of these tumors occur sporadically; however, radiation exposure, chronic lymphedema, and certain toxins including vinyl chloride and thorium dioxide are known risk factors.¹³

Undifferentiated sarcomas have no specific features and typically consist of primitive mesenchymal cells.

Clinical Evaluation

›  Case Presentation

Initial Presentation and History

A 55-year-old man presents to his primary care physician with a painless mass in his anterior thigh. The mass has been present for the past 3 months and he believes that it is enlarging. The patient has a history of well-controlled hypertension and hyperlipidemia. His medications include atorvastatin and hydrochlorothiazide. He has no known drug allergies. Family history is notable for diabetes and hypertension. He drinks 4 to 5 alcoholic drinks a week and he is a former smoker. He quit smoking in his 30s and only smoked intermittently prior to quitting. He denies any illicit drug use. He works as a high school principal. Currently, he feels well. His review of systems is otherwise noncontributory.

Physical Examination

On physical exam, he is afebrile with a blood pressure of 132/75 mm Hg, respiratory rate of 10 breaths/min, and oxygen saturation of 99% on room air. He is a well appearing, overweight male. His head and neck exam is unremarkable. Lung exam reveals clear breath sounds, and cardiac exam reveals a regular rate and rhythm. His abdomen is obese, soft, and without hepatosplenomegaly. There is a large, fixed mass on the anterior lateral aspect of his right thigh. He has no appreciable lymphadenopathy. His neurological exam is unremarkable.

• What are risk factors for sarcoma?

There are few known risk factors for sarcoma. Established risks factors include prior radiation therapy, chronic lymphedema, viruses, and genetic cancer syndromes including Li-Fraumeni syndrome, hereditary retinoblastoma, and NF-1. Other environmental exposures include phenoxyacetic acids and chlorophenols.¹⁴ The majority of cases are sporadic, with only a minority of patients having one of these known risk factors.¹⁵ Up to one third of sarcomas have a specific translocation and are driven by fusion oncogenes (Table 1).

• What is the typical presentation for sarcomas?

A painless mass is the most typical presenting symptom. Size at presentation varies based on location, with extremity and head and neck locations typically presenting at smaller sizes than retroperitoneal tumors.¹⁴ Patients may experience pain and numbness as the mass enlarges and impinges on surrounding structures including nerves and vasculature. The vast majority of patients are without systemic symptoms.

• How is sarcoma staged?

The American Joint Committee on Cancer (AJCC) staging system is the most widely used staging system in the United States. The latest AJCC manual was updated in 2010 to include a 3-tiered grading system where the tumor is classified according to tumor size, lymph node involvement, metastases, and grade at time of diagnosis (Table 2 and Table 3). Additionally, tumor depth in relation to deep fascia is also taken into account, with superficial tumors being assigned a designation of “a” and deep tumors a designation of “b.”

Previously, 2 of the most widely used grading systems were the National Cancer Institute (NCI) and French Federation of Cancer Centers Sarcoma Group (FNCLCC) systems, both 3-tier grading systems. The main components that determine the NCI grade are the tumor’s histologic type and location and the amount of tumor necrosis. The FNCLCC system evaluation focuses on tumor differentiation, mitotic rate, and amount of tumor necrosis. A study that compared the NCI and FNCLCC grading systems found that FNCLCC was a better predictor of mortality and distant metastasis.¹⁶ Previously, the AJCC was a 4-tier grading system, but the 2010 version was updated to the 3-tier FNCLCC grading system. Additionally, the AJCC system has reclassified single lymph node disease as stage III as it confers better survival than metastatic disease.¹⁷ It is important that pathology be evaluated by a sarcoma specialist as disagreements with regard to histologic subtype and grade are common.^18,19

• What are the most important prognostic factors?

Prognostic factors include grade, size, and presence of metastases at presentation. Best survival is associated with low-grade, small tumors with no metastases at time of diagnosis.¹⁴

• What imaging should be considered?

Imaging should be undertaken to help differentiate between benign and malignant lesions. Ideally, it should be undertaken before a biopsy is planned as the imaging can be used to plan biopsy as well as provide invaluable prognostic information. There are several imaging modalities that should be considered during the preliminary work-up and staging of STSs. Conventional imaging includes magnetic resonance imaging (MRI) of the original tumor site; computed tomography (CT) to evaluate for pulmonary metastases and, depending on location, liver metastases; and in the case of small, low-grade tumors, chest radiography. MRI is considered the test of choice for soft tissue masses and can help delineate benign masses such as hematomas, lipomas, and hemangiomas from sarcomas.²⁰ It is difficult to compare the accuracy of positron emission tomography (PET)/CT to CT and MRI because most studies have evaluated PET/CT in parallel with CT and MRI.²¹ Tateishi et al compared the accuracy of conventional imaging, PET/CT, and PET/CT combined with conventional imaging at determining the TNM staging for 117 patients. They found that conventional imaging correctly classified 77% of patients, PET alone correctly classified 70%, PET/CT correctly classified 83%, and PET/CT combined with conventional imaging correctly staged 87%.²²

• Which subtypes are most likely to metastasize?

Although the vast majority of sarcomas spread hematogenously, 3 have a propensity to spread lymphogenously: epithelioid sarcoma, rhabdomyosarcoma, and clear-cell sarcoma. Additionally, certain subtypes are more likely to metastasize: leiomyosarcomas, synovial sarcomas, neurogenic sarcomas, rhabdomyosarcomas, and epithelioid sarcomas.²³ Sarcomas metastasize to the lungs more frequently than to the liver. The metastatic pattern is defined primarily by sarcoma subtype and site of primary tumor. Sarcomas rarely metastasize to the brain (~1%).

Management

›  Case Continued

The patient undergoes an ultrasound to better visualize the mass. Given the heterogeneous character of the mass, he is referred for an MRI to evaluate the mass and a CT scan of the chest, abdomen, and pelvis to evaluate for distant metastases. MRI reveals a 5.1 cm × 4.6 cm heterogeneous mass invading the superficial fascia of the rectus femoris muscle. No suspicious lymph nodes or other masses are identified on imaging. The patient next undergoes an image-guided core needle biopsy. Pathology from that procedure is consistent with a stage III, T2bNxMx, grade 3, dedifferentiated liposarcoma.

• What is the best management approach for this patient?

Surgery

Surgery is the mainstay of treatment for STS. Patients with the best prognosis are those who undergo complete resection with negative surgical margins.^24,25 Goal tumor-free margin is 1 to 3 cm.²⁶ Complete resection confers the best long-term survival. Both local and metastatic recurrence is higher in patients with incomplete resection and positive margins.^24,25 In a study that analyzed 2084 localized primary STSs, patients with negative margins had a local recurrence rate of 15% versus a rate of 28% in patients with positive margins. This translated into higher 5-year local recurrence-free survival for patients with negative surgical margins (82%) compared to patients with positive margins (65%).²⁷ Another study similarly found that patients with negative margins at referral to their institution who underwent postoperative radiation had high local control rates of 93% (95% confidence interval [CI] 87% to 97%) at 5, 10, and 15 years.²⁶ Although radiation improves local control, neither preoperative or postoperative radiation has been shown to improve progression-free or overall survival.²⁸ Other factors that are associated with risk of recurrence are tumor location, history of previous recurrence, age of patient, histopathology, tumor grade, and tumor size. Approximately 40% to 50% of patients with high-grade tumors (defined as size > 5 cm, deep location, and high grade) will develop distant metastases.²⁹

Zagars et al found that positive or uncertain resection margin had a relative risk of local recurrence of 2.0 (95% CI 1.3 to 3.1; P = 0.002), and presentation with locally recurrent disease (vs new tumor) had a relative risk of local recurrence of 2.0 (95% CI 1.2 to 3.4; P = 0.013).²⁶ Patients with STS of head and neck and deep trunk have higher recurrence rates than those with superficial trunk and extremity STS. A single-institution retrospective review demonstrated that patients with completely resectable retroperitoneal sarcomas have longer median survival (103 months) compared to patients with incompletely resected abdominal sarcomas (18 months).²⁵Rosenberg and colleagues compared amputation to limb-sparing surgery and radiation.²⁴ Their prospective analysis of 65 patients found no difference in disease-free and overall survival between the 2 treatment groups.The limb-sparing treatment group had higher rates of local recurrence, which was highly correlated with positive surgical margins on pathology.²⁴ Evidence from this and similar studies has resulted in radical amputations being replaced by conservative limb-sparing procedures and radiation therapy. In those found to have positive margins, re-resection is an option for some. Patients who undergo re-resection have higher local control rates than patients with positive margins who do not undergo re-resection. The 5-year control rate for patients who undergo re-resection is 85% (95% CI 80% to 89%) compared to 78% (95% CI 71% to 83%) for those who do not undergo re-resection. Similarly, patients who undergo re-resection have lower rates of metastases at 5, 10, and 15 years as well as higher 5-, 10-, and 15-year disease-free survival rates.²⁶

›  Case Continued

The patient is referred for limb-sparing surgery after presentation at a multidisciplinary tumor board. Prior to undergoing resection of the tumor, he is also referred to radiation-oncology to discuss the risks and benefits of combination radiotherapy and surgery as opposed to surgical resection alone.

• What is the evidence for radiation therapy?

Radiation THERAPY

Radiation therapy is used in the preoperative, intraoperative, and postoperative settings to reduce the risk of local recurrence. There are several options for radiation, including external beam radiation therapy (EBRT), intraoperative radiation, and brachytherapy. A newer strategy, intensity-modulated radiation therapy (IMRT), utilizes 3-dimensional modeling to reduce radiation dosages. Overall there are no differences in overall survival or local recurrence rates between preoperative and postoperative radiation in STS.²⁸

The rationale behind preoperative radiation is that it reduces seeding of tumor cells, especially at the time of surgery.³⁰ Additionally, for EBRT, preoperative radiation has smaller field sizes and lower radiation doses. It can also help to reduce the size of the tumor prior to resection. Intraoperative radiation is often paired with preoperative radiation as a boost dose given only to the area of residual tumor.

Suit et al reviewed patients treated at a single institution with limb-sparing surgery and different radiation strategies. Local control rates between preoperative and postoperative radiation groups were not statistically significant. Local recurrence was linked to grade and size of the tumor in both groups. The authors did note, however, that the preoperative radiation group tended to have larger tumor sizes at baseline compared to the patients who received postoperative radiation.³⁰ A study that compared 190 patients who received preoperative and postoperative EBRT or brachytherapy (primary end point was wound complications, and local control was a secondary end point) showed a trend towards greater local control with preoperative radiation; however, the preoperative radiation group had significantly more wound complications compared to the postoperative radiation group.³¹

Yang et al found that postoperative EBRT decreases rates of local recurrence compared to surgery alone in high-grade extremity sarcomas.³² However, there were no differences in rates of distant metastases and overall survival between the 2 treatment groups. Similarly, in patients with low-grade sarcoma, there were fewer local recurrences in those who received EBRT and surgery as compared to surgery alone.³² Another study that evaluated 164 patients who received either adjuvant brachytherapy or no further therapy after complete resection found that brachytherapy reduced local recurrence in high-grade sarcomas. No difference in local recurrence rates was found in patients with low-grade sarcomas, nor was a significant difference found in the rates of distant metastases and overall survival between the 2 treatment groups.³³ With regards to IMRT, a single institution cohort experience with 41 patients who received IMRT following limb-sparing surgery had similar local control rates when compared to historical controls.³⁴

›  Case Continued

After discussion of the risks and benefits of radiation therapy, the patient opts for preoperative radiation prior to resection of his liposarcoma. He receives 50 Gy of EBRT prior to undergoing resection. Resection results in R1 margin consistent with microscopic disease. He receives 16 Gy of EBRT as a boost after recovery from his resection.²

• What is the evidence for neoadjuvant and adjuvant chemotherapy for stage I tumors?

Chemotherapy

Localized Sarcoma

For localized sarcoma, limb-sparing resection with or without radiation forms the backbone of treatment. Studies have evaluated chemotherapy in both the neoadjuvant and adjuvant settings, with the vast majority of studies evaluating doxorubicin-based chemotherapy regimens in the adjuvant settings. Due to the rare nature of sarcomas, most studies are not sufficiently powered to detect significant benefit from chemotherapy. Several trials evaluating chemotherapy regimens in the neoadjuvant and adjuvant settings needed to be terminated prematurely due to inadequate enrollment into the study.^35,36

For stage IA (T1a-Tb, N0, M0, low grade) tumors, no additional therapy is recommended after limb-sparing surgery with appropriate surgical margins. For stage IB (T2a-2b, N0, M0, low grade) tumors with insufficient margins, re-resection and radiation therapy should be considered, while for stage IIA (T1a-1b, N0, M0, G2-3) tumors preoperative or postoperative radiation therapy is recommended.² Studies have not found benefit of adjuvant chemotherapy in these low-grade, stage I tumors in terms of progression-free survival and overall survival.³⁷

• At what stage should chemotherapy be considered?

For stage IIb and stage III tumors, surgery and radiation therapy again form the backbone of therapy; however, neoadjuvant and adjuvant chemotherapy are also recommended as considerations. Anthracycline-based chemotherapy with either single-agent doxorubicin or doxorubicin and ifosfamide in combination are considered first-line chemotherapy agents in locally advanced STS.^2,29,37

Evidence regarding the efficacy of both neoadjuvant and adjuvant chemotherapy regimens in the setting of locally advanced high-grade STS has been mixed. The Sarcoma Meta-analysis Collaboration evaluated 14 trials of doxorubicin-based adjuvant chemotherapy and found a trend towards overall survival in the treatment groups that received chemotherapy.³⁷ All trials included in the meta-analysis compared patients with localized resectable soft-tissue sarcomas who were randomized to either adjuvant chemotherapy or no adjuvant chemotherapy after limb-sparing surgery with or without radiation therapy. None of the individual trials showed a significant benefit, and all trials had large confidence intervals; however, the meta-analysis showed significant benefit in the chemotherapy treatment groups with regard to local recurrence, distant recurrence, and progression-free survival. No significant difference in overall survival was found.³⁷ Pervais et al updated the Sarcoma Meta-analysis Collaboration’s 1997 meta-analysis with the inclusion of 4 new trials that evaluated doxorubicin combined with ifosfamide and found that both patients who received doxorubicin-based regimens or doxorubicin with ifosfamide had significant decreases in distant and overall recurrences. Only the trials that utilized doxorubicin and ifosfamide had an improved overall survival that was statistically significant (hazard ratio 0.56 [95% CI 0.36 to 0.85]; P = 0.01).²⁹ Although no significant heterogeneity was found among the trials included in either meta-analysis, a variety of sarcomas were included in each clinical trial evaluated. Given the extremely small number of each sarcoma subtype present in each trial, subgroup analysis is difficult and prone to inaccuracies. As a result, it is not known if certain histological subtypes are more or less responsive to chemotherapy.^37–39

One randomized controlled trial evaluated neoadjuvant chemotherapy in high-risk sarcomas defined as tumors greater than 8 cm or grade II/III tumors. This study evaluated doxorubicin and ifosfamide and found no significant difference in disease-free and overall survival in the neoadjuvant therapy group compared to the control group.³⁵ There remains controversy in the literature with regards to adjuvant chemotherapy. Many oncologists offer adjuvant chemotherapy to patients with certain stage III subtypes. Examples of subtypes that may be offered adjuvant therapy include myxoid liposarcomas, synovial sarcomas, and leiomyosarcomas.² With regards to how many cycles of chemotherapy should be considered, a noninferiority study compared 3 cycles of epirubicin and ifosfamide to 5 cycles of epirubicin and ifosfamide in patients with high-risk locally advanced adult STSs. Three cycles of preoperative epirubicin and ifosfamide was found to be noninferior to 5 cycles with regards to overall survival.³⁸

• What is this patient’s risk for recurrence?

The patient is at intermediate risk for recurrence. Numerous studies have demonstrated that tumor size, grade, and location are the most important factors to determine risk of recurrence, with larger size, higher grades, and deeper locations being associated with higher risk of recurrence. In an analysis of 1041 patients with STS of the extremities, high grade was the most important risk factor for distant metastases.³⁹ The highest risk of recurrence is within the first 2 years. Given that the patient’s initial tumor was located in the extremity, he is more likely to have a distant metastasis as his site of recurrence; individuals with retroperitoneal tumors and visceral tumors are more likely to recur locally.⁴⁰ For STSs of the extremity, distant metastases determine overall survival, whereas patients with retroperitoneal sarcomas can die from complications of local metastases.⁴¹ Once a patient develops distant metastases, the most important prognostic factor is the size of the tumor, with tumors larger than 10 cm having a relative risk of 1.5 (95% CI 1.0 to 2.0).³⁹

• What are the recommendations for surveillance?

Surveillance recommendations are based on the stage of the sarcoma. Stage I tumors are the least likely to recur either locally or distally. As a result, it is recommended that stage I tumors be followed with history and physical exam every 3 to 6 months for the first 2 to 3 years, and then annually after the first 2 to 3 years. Chest x-rays should be considered every 6 to 12 months.² For stage II–IV tumors, history and physical exam is recommended every 3 to 6 months for the first 2 to 3 years. Chest and distant metastases imaging should also be performed every 3 to 6 months during this time frame. For the next 2 years, history and physical exam and imaging are recommended every 6 months. After the first 4 to 5 years, annual follow-up is recommended.²

A study that followed 141 patients with primary extremity STSs for a median interval of 49 months found that high-grade tumors were most likely to recur during the first 2 years, with 20% of their patients recurring locally and 40% recurring distally. Chest x-rays performed during surveillance follow-up found distant lung metastases in 36 asymptomatic patients and had a positive predictive value of 92%, a negative predictive value of 97%, and a quality-adjusted life-year of $30,000.^40,41 No laboratory testing was found to aid in detection of recurrence.

›  Case Continued

The patient does well for 1 year. With physical therapy, he regains most of the strength and coordination of the lower extremity. He is followed every 3 months with chest x-rays and a MRI of the thigh for the first year. On his fourth follow-up clinic visit, he describes increased dysp-nea on exertion over the previous few weeks and is found to have multiple lung metastases in both lungs on chest x-ray. He undergoes further evaluation for metastases and is not found to have any other metastatic lesions. Bronchoscopy and biopsy of 1 of the lung nodules confirms recurrent dedifferentiated liposarcoma.

• Should this patient undergo metastectomy?

An analysis of 3149 patients with STS treated at Memorial Sloan-Kettering who developed lung metastases found that patients with pulmonary metastases have survival rates of 25%. The most important prognostic factor for survival was complete resection of all metastases.⁴² For stage IV disease, surgery is used only in certain instances. In instances where tumor is more localized or limited, removal of metastases or metastectomy can play a role in management.²

›  Case Continued

Because the patient’s metastases are limited to the lungs, he is referred for metastectomy. He undergoes wedge resection for definitive diagnosis but it is not possible to completely resect all of the metastases. He is thus referred to a medical oncologist to discuss his treatment options.

• What are treatment options for unresectable or metastatic disease?

Metastatic Disease

Unlike local and locally advanced disease, chemotherapy forms the backbone of treatment in stage IV disease. Doxorubicin and olaratumab or doxorubicin and ifosfamide in combination are considered first line in metastatic disease. Response rates for single-agent doxorubicin range from 16% to 27%, while phase 2 and phase 3 studies of doxorubicin and ifosfamide have found response rates ranging from 18% to 36%.⁴³ In addition, the effectiveness of doxorubicin and ifosfamide phase 2 and 3 trials varied. Edmonson et al found a tumor regression rate of 34% for doxorubicin and ifosfamide as compared to 20% for doxorubicin alone.⁴⁴ In comparison, Santoro et al found a response rate of 21.3% for doxorubicin alone and 25.2% for doxorubicin and ifosfamide.⁴⁵ Neither study found increased survival benefit for doxorubicin and ifosfamide when compared to doxorubicin alone. In a Cochrane review evaluating randomized trials that compared doxorubicin and combination chemotherapy regimens, response rates varied from 14% for doxorubicin in combination with streptomycin to 34% for doxorubicin and ifosfamide. Most trials did not show a significant benefit for combination therapies when compared to doxorubicin alone.⁴³ Mean survival with doxorubicin or doxorubicin and ifosfamide is 12 months. High rates of recurrence highlight the need for additional chemotherapy regimens.

The newest approved agent is olaratumab, a monoclonal antibody that binds platelet-derived growth factor receptor alpha and prevents receptor activation. A phase 1-b and phase 2 trial evaluated patients with locally advanced and metastatic STS and randomly assigned them to either olaratumab and doxorubicin or doxorubicin alone.⁴⁶ Progression-free survival for olaratumab/doxorubicin was 6.6 months (95% CI 4.1 to 8.3) compared to 4.1 months (95% CI 2.8 to 5.4) for doxorubicin alone. The objective response rate was 18.2% (95% CI 9.8 to 29.6) for olaratumab/doxorubicin compared to 7.5% (95% CI 2.5 to 6.6) for doxorubicin alone. Furthermore, the median overall survival for olaratumab plus doxorubicin was 26.5 months (95% CI 20.9 to 31.7) compared to 14.7 months for doxorubicin alone (95% CI 5.5 to 26.0). Impressively, this improved response was notable across histological types. Furthermore, patients who had previously been treated with more than 1 regimen and those who were treatment naïve had similar response rates.⁴⁶

• What are second-line treatment options?

Doxorubicin has been used in combination with several other agents including dacarbazine (DTIC) as well as DTIC and ifosfamide (MAID). Borden et al evaluated patients with metastatic STS and randomly assigned the patients to either doxorubicin or doxorubicin and DTIC. Combination therapy demonstrated better tumor response than doxorubicin alone: 30% complete or partial response for combination therapy and 18% for doxorubicin alone.⁴⁷ However, Omura et al found similar rates of efficacy between doxorubicin and combination doxorubicin and DTIC in women with recurrent or nonresectable uterine sarcomas.⁴⁸ MAID has never been directly compared in a randomized trial to doxorubicin alone. In a study that compared MAID to doxorubicin and DTIC (AD) in patients with unresectable or metastatic sarcomas, MAID had superior response rates (32% versus 17%), but there was no difference with regards to overall survival (mean survival of 12.5 months).⁴⁹

Several additional regimens have undergone evaluation in metastatic and recurrent STSs. Gemcitabine has been used both as a single agent and as part of combination therapy in many studies. Studies with gemcitabine in combination with either docetaxel or DTIC have been the most efficacious. In a phase 2 trial, patients with metastatic STS were randomly assigned to either gemcitabine alone or gemcitabine and docetaxel. Combination therapy had a higher response rate (16% versus 8%) and longer overall survival (17.9 months versus 11.5 months) than gemcitabine alone.⁵⁰ Furthermore, a phase 2 trial of gemcitabine and docetaxel in patients with unresectable leiomyosarcoma showed an overall response rate of 56%, with 3 complete and 15 partial responses among the 34 patients enrolled in the study.⁵¹ A phase 2 trial randomly assigned patients with unresectable or metastatic STS to either DTIC or combination gemcitabine and DTIC.⁵² Gemcitabine-DTIC had a superior progression-free survival at 3 months (56% [95% CI 43% to 69%]) as compared to DTIC alone (37% [95% CI 23.5% to 50%]). Furthermore, mean progression-free survival and overall survival were improved in the gemcitabine-DTIC group (4.2 months and 16.8 months) as compared to the DTIC group (2.0 months and 8.2 months).⁵² DTIC has a single-agent response rate of 16%, but has been shown to be particularly effective in the setting of leiomyosarcomas.⁴⁹

• Does response to treatment regimens differ by histologic subtype?

The majority of STS trials include many different histologic subtypes. Given the rarity of sarcomas as a whole, many trials have had difficulty recruiting adequate numbers of patients to have sufficient power to definitely determine if the treatment under investigation has clinical benefit. Furthermore, the patients recruited have been heterogeneous with regard to subtype. Many older studies hypothesized that the efficacy of chemotherapeutic agents vary based on histologic subtype; however, for most subtypes the number of individuals included in those trials was too low to evaluate efficacy based on subtype.

Some exceptions exist, however. For example, both gemcitabine-DTIC and gemcitabine-docetaxel have been found to be particularly effective in the treatment of leiomyosarcomas.^50,52 Additionally, a retrospective study found a 51% overall response rate for patients with myxoid liposarcomas treated with trabectedin.⁵³ Studies of patients with angiosarcoma treated with paclitaxel have demonstrated response rates of 43% and 53%.^54,55

• What are the newest approved and investigational agents?

A recently approved agent is trabectedin, a tris tetrahydroisoquinoline alkaloid isolated from ascidians that binds to the minor groove of DNA and causes disruptions in the cell cycle. Samuels et al reported data from a single-arm, open-label expanded access trial that evaluated patients with advanced metastatic sarcomas.⁵⁶ In this study, patients with liposarcomas and leiomyosarcomas had an objective response rate of 6.9% (95% CI 4.8 to 9.6) as compared to a rate of 5.9% (95% CI 4.4 to 7.8) for all assessable patients. Median survival was 11.9 months for all patients, with improved median survivals for liposarcoma and leiomyosarcomas of 16.2 months (95% CI 14.1 to 19.5) compared to 8.4 months (95% CI 7.1 to 10.7 months) for other subtypes.⁵⁶

Schöffski et al evaluated eribulin, a chemotherapeutic agent that affects microtubule dynamics, in a phase 2 trial of patients with progressive or high-grade STS with progression on previous chemotherapy. They found a median progression-free survival of 2.6 months (95% CI 1.7 to 6.2) for adipocytic sarcoma, 2.9 months (95% CI 2.4 to 4.6) for leiomyosarcoma, 2.6 months (95% CI 2.3 to 4.3) for synovial sarcoma, and 2.1 months (95% CI 1.4 to 2.9) for other sarcomas.⁵⁷

Van der Graaf and colleagues randomly assigned patients with metastatic nonadipocytic STS to pazopanib or placebo in a phase 3 trial. Pazopanib is a small-molecule endothelial growth factor inhibitor with activity against vascular endothelial growth factors 1, 2, and 3 as well as platelet-derived growth factors. Median progression-free survival was 4.6 months (95% CI 3.7 to 4.8) with pazopanib compared to 1.6 months (95% CI 0.9 to 1.8) with placebo.⁵⁸ Adipocytic sarcomas (liposarcomas) were excluded from the trial because phase 2 trials had found a lower rate of progression-free survival (26%) for them compared to other subtypes.

• What are the most common toxicities associated with the approved and investigational chemotherapeutic agents?

Toxicities were seen with each of the regimens studied and were common in the randomized trials, with higher rates of toxicities in the combination chemotherapy regimens. The most common toxicities are myelosuppression, nausea, and vomiting. In the doxorubicin trials, the most common toxicities were myelosuppression, nausea, and vomiting.⁴⁴

Ifosfamide both as an individual agent and in combination with doxorubicin has higher rates and higher grades of toxicity than doxorubicin alone. Myelosuppression is the most common toxicity associated with ifosfamide, and the most commonly affected cell line is leukocytes.⁴⁴ Combination doxorubicin and ifosfamide also had high rates of nausea and vomiting (95%) and alopecia (100%).³⁵Neutropenia is the most common toxicity associated with gemcitabine and dacarbazine, while their most common nonhematologic toxicities are fatigue and nausea.^52,59 Trabectedin’s most common toxicities are nausea (29%), neutropenia (24%), and fatigue (23%). It has also been shown to cause increased alkaline phosphatase (20%) and alanine aminotransferase (19%) levels.⁵⁶ In a phase 2 study of eribulin, 50% of patients had neutropenia, and other toxicities included fatigue, alopecia, nausea, sensory neuropathy, and thrombocytopenia.⁵⁷ Pazopanib is generally well tolerated; the most common toxicities are fatigue (65%), diarrhea (58%), nausea (54%), and hypertension (41%).⁵⁸ Higher rates of neutropenia, mucositis, nausea, vomiting, diarrhea, and transfusion reactions were seen with olaratumab and doxorubicin compared to doxorubicin alone in phase 1b and 2 studies.⁴⁶

›  Case Continued

Given his poor prognosis with unresectable metastatic undifferentiated liposarcoma, the patient considers a clinical trial prior to undergoing combined therapy with doxorubicin and ifosfamide. He tolerates therapy well with stable disease at 6 months.

Conclusion

STSs are a heterogeneous collection of rare tumors. Low-grade, localized tumors have the best prognosis, and patients who undergo complete resection have the best long-term survival. Due to the rarity of STSs, trials often have limited enrollment, and little progress has been made with regards to treatment and survival rates for metastatic and unresectable disease. All patients should be evaluated and treated at specialized sarcoma centers. This case highlights the need for continued research and clinical trials to improve overall survival of patients with sarcoma. TSJ

CORRESPONDENCE

Ashley Pariser, MD, Resident, Department of Medicine, Northwestern University Feinberg School of Medicine Chicago, IL. Accepted for publication Jan/Feb 2017; Hosp Phys; Vol. 12, Part1

Introduction

Soft tissue sarcomas (STSs) are rare adult tumors, with 3.4 new cases per 100,000 persons or 12,310 expected new cases in 2016.¹ Sarcomas are a heterogeneous collection of tumors that affect fat, muscle, nerve, nerve sheath, vascular, and connective tissues. There are more than 50 histological subtypes that comprise this diverse category of tumors. Treatment varies by stage, with limb-sparing surgery representing the mainstay of curative-intent treatment. Radiation and chemotherapy may also be considered depending on the size, grade, and location of the tumor. Survival rates have been stagnant until recently, with a disease-specific survival hovering around 65%.¹ Given the complexity of these cases, all patients ideally should be evaluated and treated by a multidisciplinary team at an institution with extensive experience treating STS.²

Epidemiology and Classification

The most common STS subtypes are gastrointestinal stromal tumor (GIST), undifferentiate pleomorphic sarcoma (previously referred to as malignant fibrous histiocytoma), liposarcoma, leiomyosarcoma, synovial sarcoma, malignant peripheral nerve sheath tumor, rhabdomyosarcoma, and unclassified sarcoma.³ Liposarcoma is one of the most common subtypes, comprising 20% of all STSs; it is subdivided into well-differentiated/dedifferentiated liposarcomas, myxoid/round cell liposarcomas, and pleomorphic liposarcomas. Well-differentiated liposarcomas tend to occur in the retroperitoneum and limbs, while both myxoid and round cell as well as pleomorphic liposarcomas more commonly originate on the limbs. Histology varies based on subtype and ranges from mature-appearing adipocytes and fibroblasts to undifferentiated cells with minimal lipogenic differentiation.⁴

Leiomyosarcomas are smooth muscle tumors and are usually located in the retroperitoneum, but have also been associated with peripheral soft tissue and vasculature. Typical histology ranges from well-defined areas of spindle-shaped cells to poorly differentiated anaplastic spindle cells.^5,6 Synovial sarcomas are a distinct type of STS that can show epithelial differentiation and account for 5% of adult STSs. The extremities are the most common presenting location (90%).⁷

Rhabdomyosarcomas are skeletal muscle tumors and are further subdivided into embryonal, alveolar, and pleomorphic subtypes. Embryonal histology ranges from primitive mesenchymal-appearing cells to highly differentiated muscle cells. Alveolar rhabdomyosarcoma has the worst prognosis of the subtypes and consists of round cells with high nuclear-to-chromatin ratios that form “glandular-like” or “alveolar” spaces.⁸ Pleomorphic rhabdomyosarcomas are composed of rhabdomyoblasts that can affect many different locations, but most commonly present on the lower extremities.⁹

Malignant peripheral nerve sheath tumor (MPNST) comprises 5% to 10% of all STSs. These tumors are associated with neurofibromatosis type 1 (NF-1), with 25% to 50% of tumors occurring in NF-1 patients. Additionally, most patients have a truncating lesion in the NF1 gene on chromosome 17.¹⁰ Anghileri et al in their single institution analysis of 205 patients with MPNSTs found the 2 most common presenting sites were the trunk and extremities. Histologically, these tumors have dense fascicles of spindle cells.¹⁰

GISTs are the most common STS of the gastrointestinal (GI) tract. Previously, GISTs were classified as smooth muscle tumors and were not accounted for in the literature as a separate entity distinct from leiomyomas, leiomyoblastomas, and leiomyosarcomas.¹¹ GISTs are found throughout the GI tract: the most common sites are the stomach (60%) and small intestine (30%). Less common sites include duodenum (4%–5%), esophagus (1%), rectum (1%–2%), and appendix (< 0.2%).¹² GISTs can be spindle cell, epithelioid, or mesenchymal tumors. Immunohistochemically, GISTs are KIT (CD117) positive. Other cell markers that are also commonly positive include CD34 (60%–70%) and smooth muscle actin (SMA) (25%).¹¹ The majority of GISTs (80%) have an activating c-KIT gene mutation. The most common mutation site is exon 11, with less common c-KIT gene mutations also occurring at exon 9 or 13. Not all GISTs have KIT mutations. The second most common mutation is the PDGFRA mutation (5%–10% of GISTs).² A minority of GISTs are negative for both KIT and PDGFRA mutations. These tumors were previously called wild-type, but as the majority have either a succinate dehydrogenase (SDH) loss of function or loss of SDHB protein expression, they are now referred to as SDH-deficient GISTs.² GISTs vary in aggressiveness from incidental to aggressive. Typically, small intestine and rectal GISTs are more aggressive than gastric GISTs. Both size and mitotic rate help to predict the metastatic potential of the tumor. Tumors less than 2 cm in size and having a mitotic rate of less than 5 per 50 high-power fields (hpf) have the lowest risk of metastases, while tumors greater than 5 cm and with more than 5 mitoses per 50 hpf have the highest rates of metastases.¹²

Angiosarcomas are rare tumors comprising 4% of all STSs. Although they can occur in any site, the majority are cutaneous and occur most frequently in the head and neck regions. These tumors are either of vascular or lymphatic origin and are comprised of abnormal, pleomorphic, malignant endothelial cells. The most useful immunohistochemical markers include von Willebrand factor, CD31, and Ulex europaeus agglutinin 1. The majority of these tumors occur sporadically; however, radiation exposure, chronic lymphedema, and certain toxins including vinyl chloride and thorium dioxide are known risk factors.¹³

Undifferentiated sarcomas have no specific features and typically consist of primitive mesenchymal cells.

Clinical Evaluation

›  Case Presentation

Initial Presentation and History

A 55-year-old man presents to his primary care physician with a painless mass in his anterior thigh. The mass has been present for the past 3 months and he believes that it is enlarging. The patient has a history of well-controlled hypertension and hyperlipidemia. His medications include atorvastatin and hydrochlorothiazide. He has no known drug allergies. Family history is notable for diabetes and hypertension. He drinks 4 to 5 alcoholic drinks a week and he is a former smoker. He quit smoking in his 30s and only smoked intermittently prior to quitting. He denies any illicit drug use. He works as a high school principal. Currently, he feels well. His review of systems is otherwise noncontributory.

Physical Examination

On physical exam, he is afebrile with a blood pressure of 132/75 mm Hg, respiratory rate of 10 breaths/min, and oxygen saturation of 99% on room air. He is a well appearing, overweight male. His head and neck exam is unremarkable. Lung exam reveals clear breath sounds, and cardiac exam reveals a regular rate and rhythm. His abdomen is obese, soft, and without hepatosplenomegaly. There is a large, fixed mass on the anterior lateral aspect of his right thigh. He has no appreciable lymphadenopathy. His neurological exam is unremarkable.

• What are risk factors for sarcoma?

There are few known risk factors for sarcoma. Established risks factors include prior radiation therapy, chronic lymphedema, viruses, and genetic cancer syndromes including Li-Fraumeni syndrome, hereditary retinoblastoma, and NF-1. Other environmental exposures include phenoxyacetic acids and chlorophenols.¹⁴ The majority of cases are sporadic, with only a minority of patients having one of these known risk factors.¹⁵ Up to one third of sarcomas have a specific translocation and are driven by fusion oncogenes (Table 1).

• What is the typical presentation for sarcomas?

A painless mass is the most typical presenting symptom. Size at presentation varies based on location, with extremity and head and neck locations typically presenting at smaller sizes than retroperitoneal tumors.¹⁴ Patients may experience pain and numbness as the mass enlarges and impinges on surrounding structures including nerves and vasculature. The vast majority of patients are without systemic symptoms.

• How is sarcoma staged?

The American Joint Committee on Cancer (AJCC) staging system is the most widely used staging system in the United States. The latest AJCC manual was updated in 2010 to include a 3-tiered grading system where the tumor is classified according to tumor size, lymph node involvement, metastases, and grade at time of diagnosis (Table 2 and Table 3). Additionally, tumor depth in relation to deep fascia is also taken into account, with superficial tumors being assigned a designation of “a” and deep tumors a designation of “b.”

Previously, 2 of the most widely used grading systems were the National Cancer Institute (NCI) and French Federation of Cancer Centers Sarcoma Group (FNCLCC) systems, both 3-tier grading systems. The main components that determine the NCI grade are the tumor’s histologic type and location and the amount of tumor necrosis. The FNCLCC system evaluation focuses on tumor differentiation, mitotic rate, and amount of tumor necrosis. A study that compared the NCI and FNCLCC grading systems found that FNCLCC was a better predictor of mortality and distant metastasis.¹⁶ Previously, the AJCC was a 4-tier grading system, but the 2010 version was updated to the 3-tier FNCLCC grading system. Additionally, the AJCC system has reclassified single lymph node disease as stage III as it confers better survival than metastatic disease.¹⁷ It is important that pathology be evaluated by a sarcoma specialist as disagreements with regard to histologic subtype and grade are common.^18,19

• What are the most important prognostic factors?

Prognostic factors include grade, size, and presence of metastases at presentation. Best survival is associated with low-grade, small tumors with no metastases at time of diagnosis.¹⁴

• What imaging should be considered?

Imaging should be undertaken to help differentiate between benign and malignant lesions. Ideally, it should be undertaken before a biopsy is planned as the imaging can be used to plan biopsy as well as provide invaluable prognostic information. There are several imaging modalities that should be considered during the preliminary work-up and staging of STSs. Conventional imaging includes magnetic resonance imaging (MRI) of the original tumor site; computed tomography (CT) to evaluate for pulmonary metastases and, depending on location, liver metastases; and in the case of small, low-grade tumors, chest radiography. MRI is considered the test of choice for soft tissue masses and can help delineate benign masses such as hematomas, lipomas, and hemangiomas from sarcomas.²⁰ It is difficult to compare the accuracy of positron emission tomography (PET)/CT to CT and MRI because most studies have evaluated PET/CT in parallel with CT and MRI.²¹ Tateishi et al compared the accuracy of conventional imaging, PET/CT, and PET/CT combined with conventional imaging at determining the TNM staging for 117 patients. They found that conventional imaging correctly classified 77% of patients, PET alone correctly classified 70%, PET/CT correctly classified 83%, and PET/CT combined with conventional imaging correctly staged 87%.²²

• Which subtypes are most likely to metastasize?

Although the vast majority of sarcomas spread hematogenously, 3 have a propensity to spread lymphogenously: epithelioid sarcoma, rhabdomyosarcoma, and clear-cell sarcoma. Additionally, certain subtypes are more likely to metastasize: leiomyosarcomas, synovial sarcomas, neurogenic sarcomas, rhabdomyosarcomas, and epithelioid sarcomas.²³ Sarcomas metastasize to the lungs more frequently than to the liver. The metastatic pattern is defined primarily by sarcoma subtype and site of primary tumor. Sarcomas rarely metastasize to the brain (~1%).

Management

›  Case Continued

The patient undergoes an ultrasound to better visualize the mass. Given the heterogeneous character of the mass, he is referred for an MRI to evaluate the mass and a CT scan of the chest, abdomen, and pelvis to evaluate for distant metastases. MRI reveals a 5.1 cm × 4.6 cm heterogeneous mass invading the superficial fascia of the rectus femoris muscle. No suspicious lymph nodes or other masses are identified on imaging. The patient next undergoes an image-guided core needle biopsy. Pathology from that procedure is consistent with a stage III, T2bNxMx, grade 3, dedifferentiated liposarcoma.

• What is the best management approach for this patient?

Surgery

Surgery is the mainstay of treatment for STS. Patients with the best prognosis are those who undergo complete resection with negative surgical margins.^24,25 Goal tumor-free margin is 1 to 3 cm.²⁶ Complete resection confers the best long-term survival. Both local and metastatic recurrence is higher in patients with incomplete resection and positive margins.^24,25 In a study that analyzed 2084 localized primary STSs, patients with negative margins had a local recurrence rate of 15% versus a rate of 28% in patients with positive margins. This translated into higher 5-year local recurrence-free survival for patients with negative surgical margins (82%) compared to patients with positive margins (65%).²⁷ Another study similarly found that patients with negative margins at referral to their institution who underwent postoperative radiation had high local control rates of 93% (95% confidence interval [CI] 87% to 97%) at 5, 10, and 15 years.²⁶ Although radiation improves local control, neither preoperative or postoperative radiation has been shown to improve progression-free or overall survival.²⁸ Other factors that are associated with risk of recurrence are tumor location, history of previous recurrence, age of patient, histopathology, tumor grade, and tumor size. Approximately 40% to 50% of patients with high-grade tumors (defined as size > 5 cm, deep location, and high grade) will develop distant metastases.²⁹

Zagars et al found that positive or uncertain resection margin had a relative risk of local recurrence of 2.0 (95% CI 1.3 to 3.1; P = 0.002), and presentation with locally recurrent disease (vs new tumor) had a relative risk of local recurrence of 2.0 (95% CI 1.2 to 3.4; P = 0.013).²⁶ Patients with STS of head and neck and deep trunk have higher recurrence rates than those with superficial trunk and extremity STS. A single-institution retrospective review demonstrated that patients with completely resectable retroperitoneal sarcomas have longer median survival (103 months) compared to patients with incompletely resected abdominal sarcomas (18 months).²⁵Rosenberg and colleagues compared amputation to limb-sparing surgery and radiation.²⁴ Their prospective analysis of 65 patients found no difference in disease-free and overall survival between the 2 treatment groups.The limb-sparing treatment group had higher rates of local recurrence, which was highly correlated with positive surgical margins on pathology.²⁴ Evidence from this and similar studies has resulted in radical amputations being replaced by conservative limb-sparing procedures and radiation therapy. In those found to have positive margins, re-resection is an option for some. Patients who undergo re-resection have higher local control rates than patients with positive margins who do not undergo re-resection. The 5-year control rate for patients who undergo re-resection is 85% (95% CI 80% to 89%) compared to 78% (95% CI 71% to 83%) for those who do not undergo re-resection. Similarly, patients who undergo re-resection have lower rates of metastases at 5, 10, and 15 years as well as higher 5-, 10-, and 15-year disease-free survival rates.²⁶

›  Case Continued

The patient is referred for limb-sparing surgery after presentation at a multidisciplinary tumor board. Prior to undergoing resection of the tumor, he is also referred to radiation-oncology to discuss the risks and benefits of combination radiotherapy and surgery as opposed to surgical resection alone.

• What is the evidence for radiation therapy?

Radiation THERAPY

Radiation therapy is used in the preoperative, intraoperative, and postoperative settings to reduce the risk of local recurrence. There are several options for radiation, including external beam radiation therapy (EBRT), intraoperative radiation, and brachytherapy. A newer strategy, intensity-modulated radiation therapy (IMRT), utilizes 3-dimensional modeling to reduce radiation dosages. Overall there are no differences in overall survival or local recurrence rates between preoperative and postoperative radiation in STS.²⁸

The rationale behind preoperative radiation is that it reduces seeding of tumor cells, especially at the time of surgery.³⁰ Additionally, for EBRT, preoperative radiation has smaller field sizes and lower radiation doses. It can also help to reduce the size of the tumor prior to resection. Intraoperative radiation is often paired with preoperative radiation as a boost dose given only to the area of residual tumor.

Suit et al reviewed patients treated at a single institution with limb-sparing surgery and different radiation strategies. Local control rates between preoperative and postoperative radiation groups were not statistically significant. Local recurrence was linked to grade and size of the tumor in both groups. The authors did note, however, that the preoperative radiation group tended to have larger tumor sizes at baseline compared to the patients who received postoperative radiation.³⁰ A study that compared 190 patients who received preoperative and postoperative EBRT or brachytherapy (primary end point was wound complications, and local control was a secondary end point) showed a trend towards greater local control with preoperative radiation; however, the preoperative radiation group had significantly more wound complications compared to the postoperative radiation group.³¹

Yang et al found that postoperative EBRT decreases rates of local recurrence compared to surgery alone in high-grade extremity sarcomas.³² However, there were no differences in rates of distant metastases and overall survival between the 2 treatment groups. Similarly, in patients with low-grade sarcoma, there were fewer local recurrences in those who received EBRT and surgery as compared to surgery alone.³² Another study that evaluated 164 patients who received either adjuvant brachytherapy or no further therapy after complete resection found that brachytherapy reduced local recurrence in high-grade sarcomas. No difference in local recurrence rates was found in patients with low-grade sarcomas, nor was a significant difference found in the rates of distant metastases and overall survival between the 2 treatment groups.³³ With regards to IMRT, a single institution cohort experience with 41 patients who received IMRT following limb-sparing surgery had similar local control rates when compared to historical controls.³⁴

›  Case Continued

After discussion of the risks and benefits of radiation therapy, the patient opts for preoperative radiation prior to resection of his liposarcoma. He receives 50 Gy of EBRT prior to undergoing resection. Resection results in R1 margin consistent with microscopic disease. He receives 16 Gy of EBRT as a boost after recovery from his resection.²

• What is the evidence for neoadjuvant and adjuvant chemotherapy for stage I tumors?

Chemotherapy

Localized Sarcoma

For localized sarcoma, limb-sparing resection with or without radiation forms the backbone of treatment. Studies have evaluated chemotherapy in both the neoadjuvant and adjuvant settings, with the vast majority of studies evaluating doxorubicin-based chemotherapy regimens in the adjuvant settings. Due to the rare nature of sarcomas, most studies are not sufficiently powered to detect significant benefit from chemotherapy. Several trials evaluating chemotherapy regimens in the neoadjuvant and adjuvant settings needed to be terminated prematurely due to inadequate enrollment into the study.^35,36

For stage IA (T1a-Tb, N0, M0, low grade) tumors, no additional therapy is recommended after limb-sparing surgery with appropriate surgical margins. For stage IB (T2a-2b, N0, M0, low grade) tumors with insufficient margins, re-resection and radiation therapy should be considered, while for stage IIA (T1a-1b, N0, M0, G2-3) tumors preoperative or postoperative radiation therapy is recommended.² Studies have not found benefit of adjuvant chemotherapy in these low-grade, stage I tumors in terms of progression-free survival and overall survival.³⁷

• At what stage should chemotherapy be considered?

For stage IIb and stage III tumors, surgery and radiation therapy again form the backbone of therapy; however, neoadjuvant and adjuvant chemotherapy are also recommended as considerations. Anthracycline-based chemotherapy with either single-agent doxorubicin or doxorubicin and ifosfamide in combination are considered first-line chemotherapy agents in locally advanced STS.^2,29,37

Evidence regarding the efficacy of both neoadjuvant and adjuvant chemotherapy regimens in the setting of locally advanced high-grade STS has been mixed. The Sarcoma Meta-analysis Collaboration evaluated 14 trials of doxorubicin-based adjuvant chemotherapy and found a trend towards overall survival in the treatment groups that received chemotherapy.³⁷ All trials included in the meta-analysis compared patients with localized resectable soft-tissue sarcomas who were randomized to either adjuvant chemotherapy or no adjuvant chemotherapy after limb-sparing surgery with or without radiation therapy. None of the individual trials showed a significant benefit, and all trials had large confidence intervals; however, the meta-analysis showed significant benefit in the chemotherapy treatment groups with regard to local recurrence, distant recurrence, and progression-free survival. No significant difference in overall survival was found.³⁷ Pervais et al updated the Sarcoma Meta-analysis Collaboration’s 1997 meta-analysis with the inclusion of 4 new trials that evaluated doxorubicin combined with ifosfamide and found that both patients who received doxorubicin-based regimens or doxorubicin with ifosfamide had significant decreases in distant and overall recurrences. Only the trials that utilized doxorubicin and ifosfamide had an improved overall survival that was statistically significant (hazard ratio 0.56 [95% CI 0.36 to 0.85]; P = 0.01).²⁹ Although no significant heterogeneity was found among the trials included in either meta-analysis, a variety of sarcomas were included in each clinical trial evaluated. Given the extremely small number of each sarcoma subtype present in each trial, subgroup analysis is difficult and prone to inaccuracies. As a result, it is not known if certain histological subtypes are more or less responsive to chemotherapy.^37–39

One randomized controlled trial evaluated neoadjuvant chemotherapy in high-risk sarcomas defined as tumors greater than 8 cm or grade II/III tumors. This study evaluated doxorubicin and ifosfamide and found no significant difference in disease-free and overall survival in the neoadjuvant therapy group compared to the control group.³⁵ There remains controversy in the literature with regards to adjuvant chemotherapy. Many oncologists offer adjuvant chemotherapy to patients with certain stage III subtypes. Examples of subtypes that may be offered adjuvant therapy include myxoid liposarcomas, synovial sarcomas, and leiomyosarcomas.² With regards to how many cycles of chemotherapy should be considered, a noninferiority study compared 3 cycles of epirubicin and ifosfamide to 5 cycles of epirubicin and ifosfamide in patients with high-risk locally advanced adult STSs. Three cycles of preoperative epirubicin and ifosfamide was found to be noninferior to 5 cycles with regards to overall survival.³⁸

• What is this patient’s risk for recurrence?

The patient is at intermediate risk for recurrence. Numerous studies have demonstrated that tumor size, grade, and location are the most important factors to determine risk of recurrence, with larger size, higher grades, and deeper locations being associated with higher risk of recurrence. In an analysis of 1041 patients with STS of the extremities, high grade was the most important risk factor for distant metastases.³⁹ The highest risk of recurrence is within the first 2 years. Given that the patient’s initial tumor was located in the extremity, he is more likely to have a distant metastasis as his site of recurrence; individuals with retroperitoneal tumors and visceral tumors are more likely to recur locally.⁴⁰ For STSs of the extremity, distant metastases determine overall survival, whereas patients with retroperitoneal sarcomas can die from complications of local metastases.⁴¹ Once a patient develops distant metastases, the most important prognostic factor is the size of the tumor, with tumors larger than 10 cm having a relative risk of 1.5 (95% CI 1.0 to 2.0).³⁹

• What are the recommendations for surveillance?

Surveillance recommendations are based on the stage of the sarcoma. Stage I tumors are the least likely to recur either locally or distally. As a result, it is recommended that stage I tumors be followed with history and physical exam every 3 to 6 months for the first 2 to 3 years, and then annually after the first 2 to 3 years. Chest x-rays should be considered every 6 to 12 months.² For stage II–IV tumors, history and physical exam is recommended every 3 to 6 months for the first 2 to 3 years. Chest and distant metastases imaging should also be performed every 3 to 6 months during this time frame. For the next 2 years, history and physical exam and imaging are recommended every 6 months. After the first 4 to 5 years, annual follow-up is recommended.²

A study that followed 141 patients with primary extremity STSs for a median interval of 49 months found that high-grade tumors were most likely to recur during the first 2 years, with 20% of their patients recurring locally and 40% recurring distally. Chest x-rays performed during surveillance follow-up found distant lung metastases in 36 asymptomatic patients and had a positive predictive value of 92%, a negative predictive value of 97%, and a quality-adjusted life-year of $30,000.^40,41 No laboratory testing was found to aid in detection of recurrence.

›  Case Continued

The patient does well for 1 year. With physical therapy, he regains most of the strength and coordination of the lower extremity. He is followed every 3 months with chest x-rays and a MRI of the thigh for the first year. On his fourth follow-up clinic visit, he describes increased dysp-nea on exertion over the previous few weeks and is found to have multiple lung metastases in both lungs on chest x-ray. He undergoes further evaluation for metastases and is not found to have any other metastatic lesions. Bronchoscopy and biopsy of 1 of the lung nodules confirms recurrent dedifferentiated liposarcoma.

• Should this patient undergo metastectomy?

An analysis of 3149 patients with STS treated at Memorial Sloan-Kettering who developed lung metastases found that patients with pulmonary metastases have survival rates of 25%. The most important prognostic factor for survival was complete resection of all metastases.⁴² For stage IV disease, surgery is used only in certain instances. In instances where tumor is more localized or limited, removal of metastases or metastectomy can play a role in management.²

›  Case Continued

Because the patient’s metastases are limited to the lungs, he is referred for metastectomy. He undergoes wedge resection for definitive diagnosis but it is not possible to completely resect all of the metastases. He is thus referred to a medical oncologist to discuss his treatment options.

• What are treatment options for unresectable or metastatic disease?

Metastatic Disease

Unlike local and locally advanced disease, chemotherapy forms the backbone of treatment in stage IV disease. Doxorubicin and olaratumab or doxorubicin and ifosfamide in combination are considered first line in metastatic disease. Response rates for single-agent doxorubicin range from 16% to 27%, while phase 2 and phase 3 studies of doxorubicin and ifosfamide have found response rates ranging from 18% to 36%.⁴³ In addition, the effectiveness of doxorubicin and ifosfamide phase 2 and 3 trials varied. Edmonson et al found a tumor regression rate of 34% for doxorubicin and ifosfamide as compared to 20% for doxorubicin alone.⁴⁴ In comparison, Santoro et al found a response rate of 21.3% for doxorubicin alone and 25.2% for doxorubicin and ifosfamide.⁴⁵ Neither study found increased survival benefit for doxorubicin and ifosfamide when compared to doxorubicin alone. In a Cochrane review evaluating randomized trials that compared doxorubicin and combination chemotherapy regimens, response rates varied from 14% for doxorubicin in combination with streptomycin to 34% for doxorubicin and ifosfamide. Most trials did not show a significant benefit for combination therapies when compared to doxorubicin alone.⁴³ Mean survival with doxorubicin or doxorubicin and ifosfamide is 12 months. High rates of recurrence highlight the need for additional chemotherapy regimens.

The newest approved agent is olaratumab, a monoclonal antibody that binds platelet-derived growth factor receptor alpha and prevents receptor activation. A phase 1-b and phase 2 trial evaluated patients with locally advanced and metastatic STS and randomly assigned them to either olaratumab and doxorubicin or doxorubicin alone.⁴⁶ Progression-free survival for olaratumab/doxorubicin was 6.6 months (95% CI 4.1 to 8.3) compared to 4.1 months (95% CI 2.8 to 5.4) for doxorubicin alone. The objective response rate was 18.2% (95% CI 9.8 to 29.6) for olaratumab/doxorubicin compared to 7.5% (95% CI 2.5 to 6.6) for doxorubicin alone. Furthermore, the median overall survival for olaratumab plus doxorubicin was 26.5 months (95% CI 20.9 to 31.7) compared to 14.7 months for doxorubicin alone (95% CI 5.5 to 26.0). Impressively, this improved response was notable across histological types. Furthermore, patients who had previously been treated with more than 1 regimen and those who were treatment naïve had similar response rates.⁴⁶

• What are second-line treatment options?

Doxorubicin has been used in combination with several other agents including dacarbazine (DTIC) as well as DTIC and ifosfamide (MAID). Borden et al evaluated patients with metastatic STS and randomly assigned the patients to either doxorubicin or doxorubicin and DTIC. Combination therapy demonstrated better tumor response than doxorubicin alone: 30% complete or partial response for combination therapy and 18% for doxorubicin alone.⁴⁷ However, Omura et al found similar rates of efficacy between doxorubicin and combination doxorubicin and DTIC in women with recurrent or nonresectable uterine sarcomas.⁴⁸ MAID has never been directly compared in a randomized trial to doxorubicin alone. In a study that compared MAID to doxorubicin and DTIC (AD) in patients with unresectable or metastatic sarcomas, MAID had superior response rates (32% versus 17%), but there was no difference with regards to overall survival (mean survival of 12.5 months).⁴⁹

Several additional regimens have undergone evaluation in metastatic and recurrent STSs. Gemcitabine has been used both as a single agent and as part of combination therapy in many studies. Studies with gemcitabine in combination with either docetaxel or DTIC have been the most efficacious. In a phase 2 trial, patients with metastatic STS were randomly assigned to either gemcitabine alone or gemcitabine and docetaxel. Combination therapy had a higher response rate (16% versus 8%) and longer overall survival (17.9 months versus 11.5 months) than gemcitabine alone.⁵⁰ Furthermore, a phase 2 trial of gemcitabine and docetaxel in patients with unresectable leiomyosarcoma showed an overall response rate of 56%, with 3 complete and 15 partial responses among the 34 patients enrolled in the study.⁵¹ A phase 2 trial randomly assigned patients with unresectable or metastatic STS to either DTIC or combination gemcitabine and DTIC.⁵² Gemcitabine-DTIC had a superior progression-free survival at 3 months (56% [95% CI 43% to 69%]) as compared to DTIC alone (37% [95% CI 23.5% to 50%]). Furthermore, mean progression-free survival and overall survival were improved in the gemcitabine-DTIC group (4.2 months and 16.8 months) as compared to the DTIC group (2.0 months and 8.2 months).⁵² DTIC has a single-agent response rate of 16%, but has been shown to be particularly effective in the setting of leiomyosarcomas.⁴⁹

• Does response to treatment regimens differ by histologic subtype?

The majority of STS trials include many different histologic subtypes. Given the rarity of sarcomas as a whole, many trials have had difficulty recruiting adequate numbers of patients to have sufficient power to definitely determine if the treatment under investigation has clinical benefit. Furthermore, the patients recruited have been heterogeneous with regard to subtype. Many older studies hypothesized that the efficacy of chemotherapeutic agents vary based on histologic subtype; however, for most subtypes the number of individuals included in those trials was too low to evaluate efficacy based on subtype.

Some exceptions exist, however. For example, both gemcitabine-DTIC and gemcitabine-docetaxel have been found to be particularly effective in the treatment of leiomyosarcomas.^50,52 Additionally, a retrospective study found a 51% overall response rate for patients with myxoid liposarcomas treated with trabectedin.⁵³ Studies of patients with angiosarcoma treated with paclitaxel have demonstrated response rates of 43% and 53%.^54,55

• What are the newest approved and investigational agents?

A recently approved agent is trabectedin, a tris tetrahydroisoquinoline alkaloid isolated from ascidians that binds to the minor groove of DNA and causes disruptions in the cell cycle. Samuels et al reported data from a single-arm, open-label expanded access trial that evaluated patients with advanced metastatic sarcomas.⁵⁶ In this study, patients with liposarcomas and leiomyosarcomas had an objective response rate of 6.9% (95% CI 4.8 to 9.6) as compared to a rate of 5.9% (95% CI 4.4 to 7.8) for all assessable patients. Median survival was 11.9 months for all patients, with improved median survivals for liposarcoma and leiomyosarcomas of 16.2 months (95% CI 14.1 to 19.5) compared to 8.4 months (95% CI 7.1 to 10.7 months) for other subtypes.⁵⁶

Schöffski et al evaluated eribulin, a chemotherapeutic agent that affects microtubule dynamics, in a phase 2 trial of patients with progressive or high-grade STS with progression on previous chemotherapy. They found a median progression-free survival of 2.6 months (95% CI 1.7 to 6.2) for adipocytic sarcoma, 2.9 months (95% CI 2.4 to 4.6) for leiomyosarcoma, 2.6 months (95% CI 2.3 to 4.3) for synovial sarcoma, and 2.1 months (95% CI 1.4 to 2.9) for other sarcomas.⁵⁷

Van der Graaf and colleagues randomly assigned patients with metastatic nonadipocytic STS to pazopanib or placebo in a phase 3 trial. Pazopanib is a small-molecule endothelial growth factor inhibitor with activity against vascular endothelial growth factors 1, 2, and 3 as well as platelet-derived growth factors. Median progression-free survival was 4.6 months (95% CI 3.7 to 4.8) with pazopanib compared to 1.6 months (95% CI 0.9 to 1.8) with placebo.⁵⁸ Adipocytic sarcomas (liposarcomas) were excluded from the trial because phase 2 trials had found a lower rate of progression-free survival (26%) for them compared to other subtypes.

• What are the most common toxicities associated with the approved and investigational chemotherapeutic agents?

Toxicities were seen with each of the regimens studied and were common in the randomized trials, with higher rates of toxicities in the combination chemotherapy regimens. The most common toxicities are myelosuppression, nausea, and vomiting. In the doxorubicin trials, the most common toxicities were myelosuppression, nausea, and vomiting.⁴⁴

Ifosfamide both as an individual agent and in combination with doxorubicin has higher rates and higher grades of toxicity than doxorubicin alone. Myelosuppression is the most common toxicity associated with ifosfamide, and the most commonly affected cell line is leukocytes.⁴⁴ Combination doxorubicin and ifosfamide also had high rates of nausea and vomiting (95%) and alopecia (100%).³⁵Neutropenia is the most common toxicity associated with gemcitabine and dacarbazine, while their most common nonhematologic toxicities are fatigue and nausea.^52,59 Trabectedin’s most common toxicities are nausea (29%), neutropenia (24%), and fatigue (23%). It has also been shown to cause increased alkaline phosphatase (20%) and alanine aminotransferase (19%) levels.⁵⁶ In a phase 2 study of eribulin, 50% of patients had neutropenia, and other toxicities included fatigue, alopecia, nausea, sensory neuropathy, and thrombocytopenia.⁵⁷ Pazopanib is generally well tolerated; the most common toxicities are fatigue (65%), diarrhea (58%), nausea (54%), and hypertension (41%).⁵⁸ Higher rates of neutropenia, mucositis, nausea, vomiting, diarrhea, and transfusion reactions were seen with olaratumab and doxorubicin compared to doxorubicin alone in phase 1b and 2 studies.⁴⁶

›  Case Continued

Given his poor prognosis with unresectable metastatic undifferentiated liposarcoma, the patient considers a clinical trial prior to undergoing combined therapy with doxorubicin and ifosfamide. He tolerates therapy well with stable disease at 6 months.

Conclusion

STSs are a heterogeneous collection of rare tumors. Low-grade, localized tumors have the best prognosis, and patients who undergo complete resection have the best long-term survival. Due to the rarity of STSs, trials often have limited enrollment, and little progress has been made with regards to treatment and survival rates for metastatic and unresectable disease. All patients should be evaluated and treated at specialized sarcoma centers. This case highlights the need for continued research and clinical trials to improve overall survival of patients with sarcoma. TSJ

CORRESPONDENCE

Ashley Pariser, MD, Resident, Department of Medicine, Northwestern University Feinberg School of Medicine Chicago, IL. Accepted for publication Jan/Feb 2017; Hosp Phys; Vol. 12, Part1

Introduction

Soft tissue sarcomas (STSs) are rare adult tumors, with 3.4 new cases per 100,000 persons or 12,310 expected new cases in 2016.¹ Sarcomas are a heterogeneous collection of tumors that affect fat, muscle, nerve, nerve sheath, vascular, and connective tissues. There are more than 50 histological subtypes that comprise this diverse category of tumors. Treatment varies by stage, with limb-sparing surgery representing the mainstay of curative-intent treatment. Radiation and chemotherapy may also be considered depending on the size, grade, and location of the tumor. Survival rates have been stagnant until recently, with a disease-specific survival hovering around 65%.¹ Given the complexity of these cases, all patients ideally should be evaluated and treated by a multidisciplinary team at an institution with extensive experience treating STS.²

Epidemiology and Classification

The most common STS subtypes are gastrointestinal stromal tumor (GIST), undifferentiate pleomorphic sarcoma (previously referred to as malignant fibrous histiocytoma), liposarcoma, leiomyosarcoma, synovial sarcoma, malignant peripheral nerve sheath tumor, rhabdomyosarcoma, and unclassified sarcoma.³ Liposarcoma is one of the most common subtypes, comprising 20% of all STSs; it is subdivided into well-differentiated/dedifferentiated liposarcomas, myxoid/round cell liposarcomas, and pleomorphic liposarcomas. Well-differentiated liposarcomas tend to occur in the retroperitoneum and limbs, while both myxoid and round cell as well as pleomorphic liposarcomas more commonly originate on the limbs. Histology varies based on subtype and ranges from mature-appearing adipocytes and fibroblasts to undifferentiated cells with minimal lipogenic differentiation.⁴

Leiomyosarcomas are smooth muscle tumors and are usually located in the retroperitoneum, but have also been associated with peripheral soft tissue and vasculature. Typical histology ranges from well-defined areas of spindle-shaped cells to poorly differentiated anaplastic spindle cells.^5,6 Synovial sarcomas are a distinct type of STS that can show epithelial differentiation and account for 5% of adult STSs. The extremities are the most common presenting location (90%).⁷

Rhabdomyosarcomas are skeletal muscle tumors and are further subdivided into embryonal, alveolar, and pleomorphic subtypes. Embryonal histology ranges from primitive mesenchymal-appearing cells to highly differentiated muscle cells. Alveolar rhabdomyosarcoma has the worst prognosis of the subtypes and consists of round cells with high nuclear-to-chromatin ratios that form “glandular-like” or “alveolar” spaces.⁸ Pleomorphic rhabdomyosarcomas are composed of rhabdomyoblasts that can affect many different locations, but most commonly present on the lower extremities.⁹

Malignant peripheral nerve sheath tumor (MPNST) comprises 5% to 10% of all STSs. These tumors are associated with neurofibromatosis type 1 (NF-1), with 25% to 50% of tumors occurring in NF-1 patients. Additionally, most patients have a truncating lesion in the NF1 gene on chromosome 17.¹⁰ Anghileri et al in their single institution analysis of 205 patients with MPNSTs found the 2 most common presenting sites were the trunk and extremities. Histologically, these tumors have dense fascicles of spindle cells.¹⁰

GISTs are the most common STS of the gastrointestinal (GI) tract. Previously, GISTs were classified as smooth muscle tumors and were not accounted for in the literature as a separate entity distinct from leiomyomas, leiomyoblastomas, and leiomyosarcomas.¹¹ GISTs are found throughout the GI tract: the most common sites are the stomach (60%) and small intestine (30%). Less common sites include duodenum (4%–5%), esophagus (1%), rectum (1%–2%), and appendix (< 0.2%).¹² GISTs can be spindle cell, epithelioid, or mesenchymal tumors. Immunohistochemically, GISTs are KIT (CD117) positive. Other cell markers that are also commonly positive include CD34 (60%–70%) and smooth muscle actin (SMA) (25%).¹¹ The majority of GISTs (80%) have an activating c-KIT gene mutation. The most common mutation site is exon 11, with less common c-KIT gene mutations also occurring at exon 9 or 13. Not all GISTs have KIT mutations. The second most common mutation is the PDGFRA mutation (5%–10% of GISTs).² A minority of GISTs are negative for both KIT and PDGFRA mutations. These tumors were previously called wild-type, but as the majority have either a succinate dehydrogenase (SDH) loss of function or loss of SDHB protein expression, they are now referred to as SDH-deficient GISTs.² GISTs vary in aggressiveness from incidental to aggressive. Typically, small intestine and rectal GISTs are more aggressive than gastric GISTs. Both size and mitotic rate help to predict the metastatic potential of the tumor. Tumors less than 2 cm in size and having a mitotic rate of less than 5 per 50 high-power fields (hpf) have the lowest risk of metastases, while tumors greater than 5 cm and with more than 5 mitoses per 50 hpf have the highest rates of metastases.¹²

Angiosarcomas are rare tumors comprising 4% of all STSs. Although they can occur in any site, the majority are cutaneous and occur most frequently in the head and neck regions. These tumors are either of vascular or lymphatic origin and are comprised of abnormal, pleomorphic, malignant endothelial cells. The most useful immunohistochemical markers include von Willebrand factor, CD31, and Ulex europaeus agglutinin 1. The majority of these tumors occur sporadically; however, radiation exposure, chronic lymphedema, and certain toxins including vinyl chloride and thorium dioxide are known risk factors.¹³

Undifferentiated sarcomas have no specific features and typically consist of primitive mesenchymal cells.

Clinical Evaluation

›  Case Presentation

Initial Presentation and History

A 55-year-old man presents to his primary care physician with a painless mass in his anterior thigh. The mass has been present for the past 3 months and he believes that it is enlarging. The patient has a history of well-controlled hypertension and hyperlipidemia. His medications include atorvastatin and hydrochlorothiazide. He has no known drug allergies. Family history is notable for diabetes and hypertension. He drinks 4 to 5 alcoholic drinks a week and he is a former smoker. He quit smoking in his 30s and only smoked intermittently prior to quitting. He denies any illicit drug use. He works as a high school principal. Currently, he feels well. His review of systems is otherwise noncontributory.

Physical Examination

On physical exam, he is afebrile with a blood pressure of 132/75 mm Hg, respiratory rate of 10 breaths/min, and oxygen saturation of 99% on room air. He is a well appearing, overweight male. His head and neck exam is unremarkable. Lung exam reveals clear breath sounds, and cardiac exam reveals a regular rate and rhythm. His abdomen is obese, soft, and without hepatosplenomegaly. There is a large, fixed mass on the anterior lateral aspect of his right thigh. He has no appreciable lymphadenopathy. His neurological exam is unremarkable.

• What are risk factors for sarcoma?

There are few known risk factors for sarcoma. Established risks factors include prior radiation therapy, chronic lymphedema, viruses, and genetic cancer syndromes including Li-Fraumeni syndrome, hereditary retinoblastoma, and NF-1. Other environmental exposures include phenoxyacetic acids and chlorophenols.¹⁴ The majority of cases are sporadic, with only a minority of patients having one of these known risk factors.¹⁵ Up to one third of sarcomas have a specific translocation and are driven by fusion oncogenes (Table 1).

• What is the typical presentation for sarcomas?

A painless mass is the most typical presenting symptom. Size at presentation varies based on location, with extremity and head and neck locations typically presenting at smaller sizes than retroperitoneal tumors.¹⁴ Patients may experience pain and numbness as the mass enlarges and impinges on surrounding structures including nerves and vasculature. The vast majority of patients are without systemic symptoms.

• How is sarcoma staged?

The American Joint Committee on Cancer (AJCC) staging system is the most widely used staging system in the United States. The latest AJCC manual was updated in 2010 to include a 3-tiered grading system where the tumor is classified according to tumor size, lymph node involvement, metastases, and grade at time of diagnosis (Table 2 and Table 3). Additionally, tumor depth in relation to deep fascia is also taken into account, with superficial tumors being assigned a designation of “a” and deep tumors a designation of “b.”

Previously, 2 of the most widely used grading systems were the National Cancer Institute (NCI) and French Federation of Cancer Centers Sarcoma Group (FNCLCC) systems, both 3-tier grading systems. The main components that determine the NCI grade are the tumor’s histologic type and location and the amount of tumor necrosis. The FNCLCC system evaluation focuses on tumor differentiation, mitotic rate, and amount of tumor necrosis. A study that compared the NCI and FNCLCC grading systems found that FNCLCC was a better predictor of mortality and distant metastasis.¹⁶ Previously, the AJCC was a 4-tier grading system, but the 2010 version was updated to the 3-tier FNCLCC grading system. Additionally, the AJCC system has reclassified single lymph node disease as stage III as it confers better survival than metastatic disease.¹⁷ It is important that pathology be evaluated by a sarcoma specialist as disagreements with regard to histologic subtype and grade are common.^18,19

• What are the most important prognostic factors?

Prognostic factors include grade, size, and presence of metastases at presentation. Best survival is associated with low-grade, small tumors with no metastases at time of diagnosis.¹⁴

• What imaging should be considered?

Imaging should be undertaken to help differentiate between benign and malignant lesions. Ideally, it should be undertaken before a biopsy is planned as the imaging can be used to plan biopsy as well as provide invaluable prognostic information. There are several imaging modalities that should be considered during the preliminary work-up and staging of STSs. Conventional imaging includes magnetic resonance imaging (MRI) of the original tumor site; computed tomography (CT) to evaluate for pulmonary metastases and, depending on location, liver metastases; and in the case of small, low-grade tumors, chest radiography. MRI is considered the test of choice for soft tissue masses and can help delineate benign masses such as hematomas, lipomas, and hemangiomas from sarcomas.²⁰ It is difficult to compare the accuracy of positron emission tomography (PET)/CT to CT and MRI because most studies have evaluated PET/CT in parallel with CT and MRI.²¹ Tateishi et al compared the accuracy of conventional imaging, PET/CT, and PET/CT combined with conventional imaging at determining the TNM staging for 117 patients. They found that conventional imaging correctly classified 77% of patients, PET alone correctly classified 70%, PET/CT correctly classified 83%, and PET/CT combined with conventional imaging correctly staged 87%.²²

• Which subtypes are most likely to metastasize?

Although the vast majority of sarcomas spread hematogenously, 3 have a propensity to spread lymphogenously: epithelioid sarcoma, rhabdomyosarcoma, and clear-cell sarcoma. Additionally, certain subtypes are more likely to metastasize: leiomyosarcomas, synovial sarcomas, neurogenic sarcomas, rhabdomyosarcomas, and epithelioid sarcomas.²³ Sarcomas metastasize to the lungs more frequently than to the liver. The metastatic pattern is defined primarily by sarcoma subtype and site of primary tumor. Sarcomas rarely metastasize to the brain (~1%).

Management

›  Case Continued

The patient undergoes an ultrasound to better visualize the mass. Given the heterogeneous character of the mass, he is referred for an MRI to evaluate the mass and a CT scan of the chest, abdomen, and pelvis to evaluate for distant metastases. MRI reveals a 5.1 cm × 4.6 cm heterogeneous mass invading the superficial fascia of the rectus femoris muscle. No suspicious lymph nodes or other masses are identified on imaging. The patient next undergoes an image-guided core needle biopsy. Pathology from that procedure is consistent with a stage III, T2bNxMx, grade 3, dedifferentiated liposarcoma.

• What is the best management approach for this patient?

Surgery

Surgery is the mainstay of treatment for STS. Patients with the best prognosis are those who undergo complete resection with negative surgical margins.^24,25 Goal tumor-free margin is 1 to 3 cm.²⁶ Complete resection confers the best long-term survival. Both local and metastatic recurrence is higher in patients with incomplete resection and positive margins.^24,25 In a study that analyzed 2084 localized primary STSs, patients with negative margins had a local recurrence rate of 15% versus a rate of 28% in patients with positive margins. This translated into higher 5-year local recurrence-free survival for patients with negative surgical margins (82%) compared to patients with positive margins (65%).²⁷ Another study similarly found that patients with negative margins at referral to their institution who underwent postoperative radiation had high local control rates of 93% (95% confidence interval [CI] 87% to 97%) at 5, 10, and 15 years.²⁶ Although radiation improves local control, neither preoperative or postoperative radiation has been shown to improve progression-free or overall survival.²⁸ Other factors that are associated with risk of recurrence are tumor location, history of previous recurrence, age of patient, histopathology, tumor grade, and tumor size. Approximately 40% to 50% of patients with high-grade tumors (defined as size > 5 cm, deep location, and high grade) will develop distant metastases.²⁹

Zagars et al found that positive or uncertain resection margin had a relative risk of local recurrence of 2.0 (95% CI 1.3 to 3.1; P = 0.002), and presentation with locally recurrent disease (vs new tumor) had a relative risk of local recurrence of 2.0 (95% CI 1.2 to 3.4; P = 0.013).²⁶ Patients with STS of head and neck and deep trunk have higher recurrence rates than those with superficial trunk and extremity STS. A single-institution retrospective review demonstrated that patients with completely resectable retroperitoneal sarcomas have longer median survival (103 months) compared to patients with incompletely resected abdominal sarcomas (18 months).²⁵Rosenberg and colleagues compared amputation to limb-sparing surgery and radiation.²⁴ Their prospective analysis of 65 patients found no difference in disease-free and overall survival between the 2 treatment groups.The limb-sparing treatment group had higher rates of local recurrence, which was highly correlated with positive surgical margins on pathology.²⁴ Evidence from this and similar studies has resulted in radical amputations being replaced by conservative limb-sparing procedures and radiation therapy. In those found to have positive margins, re-resection is an option for some. Patients who undergo re-resection have higher local control rates than patients with positive margins who do not undergo re-resection. The 5-year control rate for patients who undergo re-resection is 85% (95% CI 80% to 89%) compared to 78% (95% CI 71% to 83%) for those who do not undergo re-resection. Similarly, patients who undergo re-resection have lower rates of metastases at 5, 10, and 15 years as well as higher 5-, 10-, and 15-year disease-free survival rates.²⁶

›  Case Continued

The patient is referred for limb-sparing surgery after presentation at a multidisciplinary tumor board. Prior to undergoing resection of the tumor, he is also referred to radiation-oncology to discuss the risks and benefits of combination radiotherapy and surgery as opposed to surgical resection alone.

• What is the evidence for radiation therapy?

Radiation THERAPY

Radiation therapy is used in the preoperative, intraoperative, and postoperative settings to reduce the risk of local recurrence. There are several options for radiation, including external beam radiation therapy (EBRT), intraoperative radiation, and brachytherapy. A newer strategy, intensity-modulated radiation therapy (IMRT), utilizes 3-dimensional modeling to reduce radiation dosages. Overall there are no differences in overall survival or local recurrence rates between preoperative and postoperative radiation in STS.²⁸

The rationale behind preoperative radiation is that it reduces seeding of tumor cells, especially at the time of surgery.³⁰ Additionally, for EBRT, preoperative radiation has smaller field sizes and lower radiation doses. It can also help to reduce the size of the tumor prior to resection. Intraoperative radiation is often paired with preoperative radiation as a boost dose given only to the area of residual tumor.

Suit et al reviewed patients treated at a single institution with limb-sparing surgery and different radiation strategies. Local control rates between preoperative and postoperative radiation groups were not statistically significant. Local recurrence was linked to grade and size of the tumor in both groups. The authors did note, however, that the preoperative radiation group tended to have larger tumor sizes at baseline compared to the patients who received postoperative radiation.³⁰ A study that compared 190 patients who received preoperative and postoperative EBRT or brachytherapy (primary end point was wound complications, and local control was a secondary end point) showed a trend towards greater local control with preoperative radiation; however, the preoperative radiation group had significantly more wound complications compared to the postoperative radiation group.³¹

Yang et al found that postoperative EBRT decreases rates of local recurrence compared to surgery alone in high-grade extremity sarcomas.³² However, there were no differences in rates of distant metastases and overall survival between the 2 treatment groups. Similarly, in patients with low-grade sarcoma, there were fewer local recurrences in those who received EBRT and surgery as compared to surgery alone.³² Another study that evaluated 164 patients who received either adjuvant brachytherapy or no further therapy after complete resection found that brachytherapy reduced local recurrence in high-grade sarcomas. No difference in local recurrence rates was found in patients with low-grade sarcomas, nor was a significant difference found in the rates of distant metastases and overall survival between the 2 treatment groups.³³ With regards to IMRT, a single institution cohort experience with 41 patients who received IMRT following limb-sparing surgery had similar local control rates when compared to historical controls.³⁴

›  Case Continued

After discussion of the risks and benefits of radiation therapy, the patient opts for preoperative radiation prior to resection of his liposarcoma. He receives 50 Gy of EBRT prior to undergoing resection. Resection results in R1 margin consistent with microscopic disease. He receives 16 Gy of EBRT as a boost after recovery from his resection.²

• What is the evidence for neoadjuvant and adjuvant chemotherapy for stage I tumors?

Chemotherapy

Localized Sarcoma

For localized sarcoma, limb-sparing resection with or without radiation forms the backbone of treatment. Studies have evaluated chemotherapy in both the neoadjuvant and adjuvant settings, with the vast majority of studies evaluating doxorubicin-based chemotherapy regimens in the adjuvant settings. Due to the rare nature of sarcomas, most studies are not sufficiently powered to detect significant benefit from chemotherapy. Several trials evaluating chemotherapy regimens in the neoadjuvant and adjuvant settings needed to be terminated prematurely due to inadequate enrollment into the study.^35,36

For stage IA (T1a-Tb, N0, M0, low grade) tumors, no additional therapy is recommended after limb-sparing surgery with appropriate surgical margins. For stage IB (T2a-2b, N0, M0, low grade) tumors with insufficient margins, re-resection and radiation therapy should be considered, while for stage IIA (T1a-1b, N0, M0, G2-3) tumors preoperative or postoperative radiation therapy is recommended.² Studies have not found benefit of adjuvant chemotherapy in these low-grade, stage I tumors in terms of progression-free survival and overall survival.³⁷

• At what stage should chemotherapy be considered?

For stage IIb and stage III tumors, surgery and radiation therapy again form the backbone of therapy; however, neoadjuvant and adjuvant chemotherapy are also recommended as considerations. Anthracycline-based chemotherapy with either single-agent doxorubicin or doxorubicin and ifosfamide in combination are considered first-line chemotherapy agents in locally advanced STS.^2,29,37

Evidence regarding the efficacy of both neoadjuvant and adjuvant chemotherapy regimens in the setting of locally advanced high-grade STS has been mixed. The Sarcoma Meta-analysis Collaboration evaluated 14 trials of doxorubicin-based adjuvant chemotherapy and found a trend towards overall survival in the treatment groups that received chemotherapy.³⁷ All trials included in the meta-analysis compared patients with localized resectable soft-tissue sarcomas who were randomized to either adjuvant chemotherapy or no adjuvant chemotherapy after limb-sparing surgery with or without radiation therapy. None of the individual trials showed a significant benefit, and all trials had large confidence intervals; however, the meta-analysis showed significant benefit in the chemotherapy treatment groups with regard to local recurrence, distant recurrence, and progression-free survival. No significant difference in overall survival was found.³⁷ Pervais et al updated the Sarcoma Meta-analysis Collaboration’s 1997 meta-analysis with the inclusion of 4 new trials that evaluated doxorubicin combined with ifosfamide and found that both patients who received doxorubicin-based regimens or doxorubicin with ifosfamide had significant decreases in distant and overall recurrences. Only the trials that utilized doxorubicin and ifosfamide had an improved overall survival that was statistically significant (hazard ratio 0.56 [95% CI 0.36 to 0.85]; P = 0.01).²⁹ Although no significant heterogeneity was found among the trials included in either meta-analysis, a variety of sarcomas were included in each clinical trial evaluated. Given the extremely small number of each sarcoma subtype present in each trial, subgroup analysis is difficult and prone to inaccuracies. As a result, it is not known if certain histological subtypes are more or less responsive to chemotherapy.^37–39

One randomized controlled trial evaluated neoadjuvant chemotherapy in high-risk sarcomas defined as tumors greater than 8 cm or grade II/III tumors. This study evaluated doxorubicin and ifosfamide and found no significant difference in disease-free and overall survival in the neoadjuvant therapy group compared to the control group.³⁵ There remains controversy in the literature with regards to adjuvant chemotherapy. Many oncologists offer adjuvant chemotherapy to patients with certain stage III subtypes. Examples of subtypes that may be offered adjuvant therapy include myxoid liposarcomas, synovial sarcomas, and leiomyosarcomas.² With regards to how many cycles of chemotherapy should be considered, a noninferiority study compared 3 cycles of epirubicin and ifosfamide to 5 cycles of epirubicin and ifosfamide in patients with high-risk locally advanced adult STSs. Three cycles of preoperative epirubicin and ifosfamide was found to be noninferior to 5 cycles with regards to overall survival.³⁸

• What is this patient’s risk for recurrence?

The patient is at intermediate risk for recurrence. Numerous studies have demonstrated that tumor size, grade, and location are the most important factors to determine risk of recurrence, with larger size, higher grades, and deeper locations being associated with higher risk of recurrence. In an analysis of 1041 patients with STS of the extremities, high grade was the most important risk factor for distant metastases.³⁹ The highest risk of recurrence is within the first 2 years. Given that the patient’s initial tumor was located in the extremity, he is more likely to have a distant metastasis as his site of recurrence; individuals with retroperitoneal tumors and visceral tumors are more likely to recur locally.⁴⁰ For STSs of the extremity, distant metastases determine overall survival, whereas patients with retroperitoneal sarcomas can die from complications of local metastases.⁴¹ Once a patient develops distant metastases, the most important prognostic factor is the size of the tumor, with tumors larger than 10 cm having a relative risk of 1.5 (95% CI 1.0 to 2.0).³⁹

• What are the recommendations for surveillance?

Surveillance recommendations are based on the stage of the sarcoma. Stage I tumors are the least likely to recur either locally or distally. As a result, it is recommended that stage I tumors be followed with history and physical exam every 3 to 6 months for the first 2 to 3 years, and then annually after the first 2 to 3 years. Chest x-rays should be considered every 6 to 12 months.² For stage II–IV tumors, history and physical exam is recommended every 3 to 6 months for the first 2 to 3 years. Chest and distant metastases imaging should also be performed every 3 to 6 months during this time frame. For the next 2 years, history and physical exam and imaging are recommended every 6 months. After the first 4 to 5 years, annual follow-up is recommended.²

A study that followed 141 patients with primary extremity STSs for a median interval of 49 months found that high-grade tumors were most likely to recur during the first 2 years, with 20% of their patients recurring locally and 40% recurring distally. Chest x-rays performed during surveillance follow-up found distant lung metastases in 36 asymptomatic patients and had a positive predictive value of 92%, a negative predictive value of 97%, and a quality-adjusted life-year of $30,000.^40,41 No laboratory testing was found to aid in detection of recurrence.

›  Case Continued

The patient does well for 1 year. With physical therapy, he regains most of the strength and coordination of the lower extremity. He is followed every 3 months with chest x-rays and a MRI of the thigh for the first year. On his fourth follow-up clinic visit, he describes increased dysp-nea on exertion over the previous few weeks and is found to have multiple lung metastases in both lungs on chest x-ray. He undergoes further evaluation for metastases and is not found to have any other metastatic lesions. Bronchoscopy and biopsy of 1 of the lung nodules confirms recurrent dedifferentiated liposarcoma.

• Should this patient undergo metastectomy?

An analysis of 3149 patients with STS treated at Memorial Sloan-Kettering who developed lung metastases found that patients with pulmonary metastases have survival rates of 25%. The most important prognostic factor for survival was complete resection of all metastases.⁴² For stage IV disease, surgery is used only in certain instances. In instances where tumor is more localized or limited, removal of metastases or metastectomy can play a role in management.²

›  Case Continued

Because the patient’s metastases are limited to the lungs, he is referred for metastectomy. He undergoes wedge resection for definitive diagnosis but it is not possible to completely resect all of the metastases. He is thus referred to a medical oncologist to discuss his treatment options.

• What are treatment options for unresectable or metastatic disease?

Metastatic Disease

Unlike local and locally advanced disease, chemotherapy forms the backbone of treatment in stage IV disease. Doxorubicin and olaratumab or doxorubicin and ifosfamide in combination are considered first line in metastatic disease. Response rates for single-agent doxorubicin range from 16% to 27%, while phase 2 and phase 3 studies of doxorubicin and ifosfamide have found response rates ranging from 18% to 36%.⁴³ In addition, the effectiveness of doxorubicin and ifosfamide phase 2 and 3 trials varied. Edmonson et al found a tumor regression rate of 34% for doxorubicin and ifosfamide as compared to 20% for doxorubicin alone.⁴⁴ In comparison, Santoro et al found a response rate of 21.3% for doxorubicin alone and 25.2% for doxorubicin and ifosfamide.⁴⁵ Neither study found increased survival benefit for doxorubicin and ifosfamide when compared to doxorubicin alone. In a Cochrane review evaluating randomized trials that compared doxorubicin and combination chemotherapy regimens, response rates varied from 14% for doxorubicin in combination with streptomycin to 34% for doxorubicin and ifosfamide. Most trials did not show a significant benefit for combination therapies when compared to doxorubicin alone.⁴³ Mean survival with doxorubicin or doxorubicin and ifosfamide is 12 months. High rates of recurrence highlight the need for additional chemotherapy regimens.

The newest approved agent is olaratumab, a monoclonal antibody that binds platelet-derived growth factor receptor alpha and prevents receptor activation. A phase 1-b and phase 2 trial evaluated patients with locally advanced and metastatic STS and randomly assigned them to either olaratumab and doxorubicin or doxorubicin alone.⁴⁶ Progression-free survival for olaratumab/doxorubicin was 6.6 months (95% CI 4.1 to 8.3) compared to 4.1 months (95% CI 2.8 to 5.4) for doxorubicin alone. The objective response rate was 18.2% (95% CI 9.8 to 29.6) for olaratumab/doxorubicin compared to 7.5% (95% CI 2.5 to 6.6) for doxorubicin alone. Furthermore, the median overall survival for olaratumab plus doxorubicin was 26.5 months (95% CI 20.9 to 31.7) compared to 14.7 months for doxorubicin alone (95% CI 5.5 to 26.0). Impressively, this improved response was notable across histological types. Furthermore, patients who had previously been treated with more than 1 regimen and those who were treatment naïve had similar response rates.⁴⁶

• What are second-line treatment options?

Doxorubicin has been used in combination with several other agents including dacarbazine (DTIC) as well as DTIC and ifosfamide (MAID). Borden et al evaluated patients with metastatic STS and randomly assigned the patients to either doxorubicin or doxorubicin and DTIC. Combination therapy demonstrated better tumor response than doxorubicin alone: 30% complete or partial response for combination therapy and 18% for doxorubicin alone.⁴⁷ However, Omura et al found similar rates of efficacy between doxorubicin and combination doxorubicin and DTIC in women with recurrent or nonresectable uterine sarcomas.⁴⁸ MAID has never been directly compared in a randomized trial to doxorubicin alone. In a study that compared MAID to doxorubicin and DTIC (AD) in patients with unresectable or metastatic sarcomas, MAID had superior response rates (32% versus 17%), but there was no difference with regards to overall survival (mean survival of 12.5 months).⁴⁹

Several additional regimens have undergone evaluation in metastatic and recurrent STSs. Gemcitabine has been used both as a single agent and as part of combination therapy in many studies. Studies with gemcitabine in combination with either docetaxel or DTIC have been the most efficacious. In a phase 2 trial, patients with metastatic STS were randomly assigned to either gemcitabine alone or gemcitabine and docetaxel. Combination therapy had a higher response rate (16% versus 8%) and longer overall survival (17.9 months versus 11.5 months) than gemcitabine alone.⁵⁰ Furthermore, a phase 2 trial of gemcitabine and docetaxel in patients with unresectable leiomyosarcoma showed an overall response rate of 56%, with 3 complete and 15 partial responses among the 34 patients enrolled in the study.⁵¹ A phase 2 trial randomly assigned patients with unresectable or metastatic STS to either DTIC or combination gemcitabine and DTIC.⁵² Gemcitabine-DTIC had a superior progression-free survival at 3 months (56% [95% CI 43% to 69%]) as compared to DTIC alone (37% [95% CI 23.5% to 50%]). Furthermore, mean progression-free survival and overall survival were improved in the gemcitabine-DTIC group (4.2 months and 16.8 months) as compared to the DTIC group (2.0 months and 8.2 months).⁵² DTIC has a single-agent response rate of 16%, but has been shown to be particularly effective in the setting of leiomyosarcomas.⁴⁹

• Does response to treatment regimens differ by histologic subtype?

The majority of STS trials include many different histologic subtypes. Given the rarity of sarcomas as a whole, many trials have had difficulty recruiting adequate numbers of patients to have sufficient power to definitely determine if the treatment under investigation has clinical benefit. Furthermore, the patients recruited have been heterogeneous with regard to subtype. Many older studies hypothesized that the efficacy of chemotherapeutic agents vary based on histologic subtype; however, for most subtypes the number of individuals included in those trials was too low to evaluate efficacy based on subtype.

Some exceptions exist, however. For example, both gemcitabine-DTIC and gemcitabine-docetaxel have been found to be particularly effective in the treatment of leiomyosarcomas.^50,52 Additionally, a retrospective study found a 51% overall response rate for patients with myxoid liposarcomas treated with trabectedin.⁵³ Studies of patients with angiosarcoma treated with paclitaxel have demonstrated response rates of 43% and 53%.^54,55

• What are the newest approved and investigational agents?

A recently approved agent is trabectedin, a tris tetrahydroisoquinoline alkaloid isolated from ascidians that binds to the minor groove of DNA and causes disruptions in the cell cycle. Samuels et al reported data from a single-arm, open-label expanded access trial that evaluated patients with advanced metastatic sarcomas.⁵⁶ In this study, patients with liposarcomas and leiomyosarcomas had an objective response rate of 6.9% (95% CI 4.8 to 9.6) as compared to a rate of 5.9% (95% CI 4.4 to 7.8) for all assessable patients. Median survival was 11.9 months for all patients, with improved median survivals for liposarcoma and leiomyosarcomas of 16.2 months (95% CI 14.1 to 19.5) compared to 8.4 months (95% CI 7.1 to 10.7 months) for other subtypes.⁵⁶

Schöffski et al evaluated eribulin, a chemotherapeutic agent that affects microtubule dynamics, in a phase 2 trial of patients with progressive or high-grade STS with progression on previous chemotherapy. They found a median progression-free survival of 2.6 months (95% CI 1.7 to 6.2) for adipocytic sarcoma, 2.9 months (95% CI 2.4 to 4.6) for leiomyosarcoma, 2.6 months (95% CI 2.3 to 4.3) for synovial sarcoma, and 2.1 months (95% CI 1.4 to 2.9) for other sarcomas.⁵⁷

Van der Graaf and colleagues randomly assigned patients with metastatic nonadipocytic STS to pazopanib or placebo in a phase 3 trial. Pazopanib is a small-molecule endothelial growth factor inhibitor with activity against vascular endothelial growth factors 1, 2, and 3 as well as platelet-derived growth factors. Median progression-free survival was 4.6 months (95% CI 3.7 to 4.8) with pazopanib compared to 1.6 months (95% CI 0.9 to 1.8) with placebo.⁵⁸ Adipocytic sarcomas (liposarcomas) were excluded from the trial because phase 2 trials had found a lower rate of progression-free survival (26%) for them compared to other subtypes.

• What are the most common toxicities associated with the approved and investigational chemotherapeutic agents?

Toxicities were seen with each of the regimens studied and were common in the randomized trials, with higher rates of toxicities in the combination chemotherapy regimens. The most common toxicities are myelosuppression, nausea, and vomiting. In the doxorubicin trials, the most common toxicities were myelosuppression, nausea, and vomiting.⁴⁴

Ifosfamide both as an individual agent and in combination with doxorubicin has higher rates and higher grades of toxicity than doxorubicin alone. Myelosuppression is the most common toxicity associated with ifosfamide, and the most commonly affected cell line is leukocytes.⁴⁴ Combination doxorubicin and ifosfamide also had high rates of nausea and vomiting (95%) and alopecia (100%).³⁵Neutropenia is the most common toxicity associated with gemcitabine and dacarbazine, while their most common nonhematologic toxicities are fatigue and nausea.^52,59 Trabectedin’s most common toxicities are nausea (29%), neutropenia (24%), and fatigue (23%). It has also been shown to cause increased alkaline phosphatase (20%) and alanine aminotransferase (19%) levels.⁵⁶ In a phase 2 study of eribulin, 50% of patients had neutropenia, and other toxicities included fatigue, alopecia, nausea, sensory neuropathy, and thrombocytopenia.⁵⁷ Pazopanib is generally well tolerated; the most common toxicities are fatigue (65%), diarrhea (58%), nausea (54%), and hypertension (41%).⁵⁸ Higher rates of neutropenia, mucositis, nausea, vomiting, diarrhea, and transfusion reactions were seen with olaratumab and doxorubicin compared to doxorubicin alone in phase 1b and 2 studies.⁴⁶

›  Case Continued

Given his poor prognosis with unresectable metastatic undifferentiated liposarcoma, the patient considers a clinical trial prior to undergoing combined therapy with doxorubicin and ifosfamide. He tolerates therapy well with stable disease at 6 months.

Conclusion

STSs are a heterogeneous collection of rare tumors. Low-grade, localized tumors have the best prognosis, and patients who undergo complete resection have the best long-term survival. Due to the rarity of STSs, trials often have limited enrollment, and little progress has been made with regards to treatment and survival rates for metastatic and unresectable disease. All patients should be evaluated and treated at specialized sarcoma centers. This case highlights the need for continued research and clinical trials to improve overall survival of patients with sarcoma. TSJ

CORRESPONDENCE

Ashley Pariser, MD, Resident, Department of Medicine, Northwestern University Feinberg School of Medicine Chicago, IL. Accepted for publication Jan/Feb 2017; Hosp Phys; Vol. 12, Part1