First-line Therapy.For patients under age 65 to 70 years with a good performance status and few comorbidities, an intensive induction regimen (such as R-CHOP/R-DHAP, Maxi-R-CHOP/R-araC, or R-DHAP) followed by consolidation with auto-HCT is commonly given, with a goal of achieving a durable (6–9 year) first remission [87,93,94]. Auto-HCT is now routinely followed by 3 years of maintenance rituximab based on the survival benefit seen in the recent LYSA trial [93]. At many centers, auto-HCT in first remission is a standard of care, with the greatest benefit seen in patients who have achieved a complete remission with no more than 2 lines of chemotherapy [95]. However, there remains some controversy about whether all patients truly benefit from auto-HCT in first remission, and current research efforts are focused on identifying patients most likely to benefit from auto-HCT and incorporation of new agents into first-line regimens. For patients who are not candidates for auto-HCT, bendamustine plus rituximab (BR) or R-CHOP alone or followed by maintenance rituximab is a reasonable approach [96]. Based on the StiL and BRIGHT trials, BR seems to have less toxicity and higher rates of response with no difference in OS when compared to R-CHOP [97,98].
In summary, dose-intense induction chemotherapy with consolidative auto-HCT results in high rates of long-term remission and can be considered in MCL patients who lack significant comorbidities and who understand the risks and benefits of this approach. For other patients, the less aggressive frontline approaches are more appropriate.
Relapsed/Refractory Disease
Despite initial high response rates, most patients with MCL will eventually relapse. For example, most patients given CHOP or R-CHOP alone as first-line therapy will relapse within 2 years [99]. In recent years, a number of therapies have emerged for relapsed/refractory MCL; however, the optimal sequencing of these is unclear. FDA-approved options for relapsed/refractory MCL include the proteasome inhibitor bortezomib [100,101], the BTK inhibitors ibrutinib [102,103] and acalabrutinib [104], and the immunomodulatory agent lenalidomide [105].
Auto-HCT can be considered for patients who did not undergo auto-HCT as part of first-line therapy and who had a reasonably long first remission [95]. Allo-HCT has curative potential in MCL with good evidence of a graft-versus-lymphoma effect. With a matched related or matched unrelated donor, the chance for treatment-related mortality is 15% to 25% at 1 to 2 years, with a 50% to 60% chance for long-term PFS. However, given the risk of treatment-related mortality and graft-versus-host disease, this option is typically reserved for patients with early relapse after auto-HCT, multiple relapses, or relatively chemotherapy-unresponsive disease [95,106]. A number of clinical trials for relapsed/refractory MCL are ongoing, and participation in these is encouraged whenever possible.
Burkitt Lymphoma
Burkitt lymphoma is a rare, aggressive and highly curable subtype of NHL. It can occur at any age, although peak incidence is in the first decade of life. There are 3 distinct clinical forms of Burkitt lymphoma [107]. The endemic form is common in African children and commonly involves the jaw and kidneys. The sporadic (nonendemic) form accounts for 1% to 2% of all lymphomas in the United States and Western Europe and usually has an abdominal presentation. The immunodeficiency-associated form is commonly seen in HIV patients with a relatively preserved CD4 cell count.
Patients typically present with rapidly growing masses and tumor lysis syndrome. CNS and bone marrow involvement are common. Burkitt lymphoma cells are high-grade, rapidly proliferating medium-sized cells with a monomorphic appearance. Biopsies show a classic histological appearance known as a “starry sky pattern” due to benign macrophages engulfing debris resulting from apoptosis. It is derived from a germinal center B cell and has distinct oncogenic pathways. Translocations such as t(8;14), t(2;8) or t(8;22) juxtapose the MYC locus with immunoglobulin heavy or light chain loci and result in MYC overexpression. Burkitt lymphoma is typically CD10-positive and BCL-2-negative, with a MYC translocation and a proliferation rate greater than 95%.
With conventional NHL regimens, Burkitt lymphoma had a poor prognosis, with complete remission in the 30% to 70% range and low rates of long-term remission. With the introduction of short-term, dose-intensive, multiagent chemotherapy regimens (adapted from pediatric acute lymphoblastic leukemia [ALL] regimens), the complete remission rate improved to 60% to 90% [107]. Early stage disease (localized or completely resected intra-abdominal disease) can have complete remission rates of 100%, with 2- to 5-year freedom-from-progression rates of 95%. CNS prophylaxis, including high-dose methotrexate, high-dose cytarabine, and intrathecal chemotherapy, is a standard component of Burkitt lymphoma regimens (CNS relapse rates can reach 50% without prophylactic therapy). Crucially, relapse after 1 to 2 years is very rare following complete response to induction therapy. Classically, several intensive regimens have been used for Burkitt lymphoma. In recent years, the most commonly used regimens have been the modified Magrath regimen of R-CODOX-M/IVAC and R-hyperCVAD. DA-EPOCH-R has also been used, typically for older, more frail, or HIV-positive patients. However, at the American Society of Hematology 2017 annual meeting, results from the NCI 9177 trial were presented which validated, in a prospective multi-center fashion, the use of DA-EPOCH-R in all Burkitt lymphoma patients [108]. In NCI 9177, low-risk patients (defined as normal LDH, ECOG performance score 0 or 1, ≤ stage II, and no tumor lesion > 7 cm) received 2 cycles of DA-EPOCH-R without intrathecal therapy followed by PET. If interim PET was negative, low-risk patients then received 1 more cycle of DA-EPOCH-R. High-risk patients with negative brain MRI and CSF cytology/flow cytometry received 2 cycles of DA-EPOCH-R with intrathecal therapy (2 doses per cycle) followed by PET. Unless interim PET showed progression, high-risk patients received 4 additional cycles of DA-EPOCH-R including methotrexate 12 mg intrathecally on days 1 and 5 (8 total doses). With a median follow-up of 36 months, this regimen resulted in an EFS of 85.7%. As expected, patients with CNS, marrow, or peripheral blood involvement fared worse. For those without CNS, marrow, or peripheral blood involvement, the results were excellent, with an EFS of 94.6% compared to 62.8% for those with CNS, bone marrow, or blood involvement at diagnosis.
Although no standard of care has been defined, patients with relapsed/refractory Burkitt lymphoma are often given standard second-line aggressive NHL regimens (eg, R-ICE); for those with chemosensitive disease, auto- or allo-HCT is often pursued, with long-term remissions possible following HCT [109].
