SABCS 2017

SAN ANTONIO – Adjuvant endocrine therapies improve outcomes of premenopausal breast cancer in the long term, with absolute benefit varying somewhat by therapy and by patient and disease characteristics, according to planned updates of a pair of pivotal phase 3 trials.

The trials – TEXT (Tamoxifen and Exemestane Trial) and SOFT (Suppression of Ovarian Function Trial) – are coordinated by the International Breast Cancer Study Group and together randomized more than 5,000 premenopausal women with early hormone receptor–positive breast cancer to 5 years of various types of adjuvant endocrine therapy. Their initial results, reported several years ago, form part of treatment guidelines that are used worldwide.

Clinical implications

These updates, along with other emerging data, can be used to optimize endocrine therapy for younger women with breast cancer, according to invited discussant Ann H. Partridge, MD, of Dana Farber Cancer Institute in Boston.

“For higher-risk disease, we should be considering OFS. At this point in time, I don’t think HER2 status alone should drive this decision,” she commented. “If you are getting OFS, what do we do, AI versus tamoxifen? Well, we do see a large improvement in disease-free survival [with AIs], so many women will want to use AIs. Yet tamoxifen is still reasonable, especially in light of the survival data.”

Data on switch strategies and extended-duration therapy are generally lacking at present for the premenopausal population, Dr. Partridge noted. “That’s something that we still need to extrapolate from data that’s predominantly in postmenopausal women.”

Another compelling question is whether OFS can be used instead of chemo for some patients. “We are increasingly recognizing that women with higher-risk anatomy and lower-risk biology having endocrine-responsive tumors may get more bang for the buck from the optimizing of hormonal therapy, and chemo may not add much,” she said.

Both short- and long-term toxicities of the various endocrine therapies and, for aromatase inhibitors, the potential for breakthrough (return of estradiol levels to premenopausal levels) also need to be considered, Dr. Partridge stressed. “And ultimately, patient preference and tolerance are key. After all, the best treatment is the one the patient will take.”

“We need to follow these women on TEXT and SOFT very long term. It would be a crime not to follow these women further out,” she maintained. “We need to conduct real-world comparative effectiveness research to understand the risks and benefits of OFS more fully in our survivors. Then, as we start to suppress more ovaries in more women with breast cancer, we need to be aware clinically of these risks, and we need to share this awareness with their primary care providers because we need to optimize in particular their cardiovascular risk factors, and screen and treat for potential comorbidities that they may be at higher risk for.”
 

Joint TEXT and SOFT update

Initial results of the joint TEXT and SOFT analysis, reported after a median follow-up of 5.7 years, showed that exemestane plus OFS was superior to tamoxifen plus OFS for the primary outcome, providing a significant 3.8% absolute gain in 5-year disease-free survival (N Engl J Med. 2014;371:107-18).

The updated joint analysis, now with a median follow-up of 9 years and based on data from 4,690 women, showed that the 8-year rate of disease-free survival was 86.8% with exemestane plus OFS versus 82.8% with tamoxifen plus OFS (hazard ratio, 0.77; P = .0006), for a similar absolute benefit of 4.0%, reported Prudence Francis, MD, of the University of Melbourne, head of Medical Oncology in the Breast Service at the Peter MacCallum Cancer Centre, Melbourne.

In stratified analysis, absolute benefit tended to be greater among women in TEXT who received chemotherapy (6.0%); intermediate among women in TEXT who did not receive chemotherapy (3.7%) and women in SOFT who received prior chemotherapy (3.7%); and less among women in SOFT who did not receive chemotherapy (1.9%).

Exemestane plus OFS was also superior to tamoxifen plus OFS in terms of breast cancer–free interval, with an absolute 4.1% benefit (P = .0002), and distant recurrence–free interval, with an absolute 2.1% benefit (P = .02). Overall survival did not differ significantly between arms.

Among the 86% of patients with HER2-negative disease, exemestane plus OFS netted an absolute disease-free survival gain of 5.4% and an absolute distant recurrence–free interval gain of 3.4%. There was a consistent relative treatment benefit across subgroups, but larger absolute benefit, on the order of 5%-9%, in women given chemotherapy and in those younger than 35 years.

“Results for the HER2-positive subgroup require further investigation,” Dr. Francis said. “The trials enrolled both before and after the routine use of adjuvant trastuzumab, and a significant proportion of the patients with HER2-positive breast cancer did not receive adjuvant HER2-targeted therapy.”

In the entire joint-analysis population, exemestane plus OFS was associated with higher rates of musculoskeletal events of grade 3 or 4 (11% vs. 6%) and osteoporosis of grade 2-4 (15% vs. 7%), while tamoxifen plus OFS was associated with a higher rate of thrombosis/embolism of grade 2-4 (2.3% vs. 1.2%) and more cases of endometrial cancer (9 vs. 4 cases). At 4 years, early discontinuation of oral endocrine therapy was greater for exemestane than for tamoxifen (25% vs. 19%).

“After longer follow-up, with a median of 9 years, the combined analysis results confirm a statistically significant improvement in disease outcomes with exemestane plus ovarian suppression. As is critical given the long natural history of estrogen receptor–positive breast cancer, follow-up in these trials is currently continuing,” Dr. Francis summarized.

“To optimally translate the observed absolute trial improvements into clinical practice, oncologists need to discuss and weigh the potential benefits and toxicities in each individual patient who is premenopausal with hormone receptor–positive breast cancer,” she recommended.

Session attendee Hope S. Rugo, MD, of the University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center, noted that exemestane had superior benefit despite the 25% rate of early discontinuation. “I wonder if one of the interpretations of that, given the toxicity of this therapy for very young women, is that we need some but maybe not so much. Maybe they don’t need 5 years altogether,” she said.

“The fact that they stopped their assigned endocrine therapy doesn’t mean that they didn’t continue any therapy. They may have switched over to tamoxifen or they may have decided they wanted to have a baby or there may have been many other things,” Dr. Francis replied, noting that analyses sorting out the reasons for early discontinuation are planned.

Session attendee Mark E. Sherman, MD, of the Mayo Clinic, Jacksonville, Fla., asked, “Do you have any ability to test for tamoxifen metabolites? It’s possible that a third to a half of patients got reduced benefit from that drug.”

Banked samples are available and a substudy is planned, according to Dr. Francis. “We haven’t got data on that yet, but yes, we are analyzing that.”
 

SOFT update

Initial results of the SOFT trial, reported after a median follow-up of 5.6 years, showed that adding OFS to tamoxifen did not significantly improve disease-free survival over tamoxifen alone in the entire trial population (N Engl J Med. 2015;372:436-46). However, there was benefit for women who received chemotherapy and remained premenopausal.

The updated SOFT analysis, now with a median follow-up of 8 years, focused mainly on the 1,018 women given tamoxifen alone and the 1,015 women given tamoxifen plus OFS. (Another 1,014 women were given exemestane plus OFS.)

“SOFT is now positive for its primary endpoint,” reported first author Gini Fleming, MD, director of the Medical Oncology Breast Program and medical oncology director of Gynecologic Oncology at University of Chicago Medicine. The 8-year disease-free survival rate was 83.2% with tamoxifen plus OFS, compared with 78.9% with tamoxifen alone (HR, 0.76; P = .009), corresponding to a 4.2% gain in this outcome. The relative benefit was identical whether patients had received chemotherapy or not, but absolute benefit was greater for those who had (5.3%), as well as for patients younger than 35 years (8.7%).

In addition, exemestane plus OFS was superior to tamoxifen alone (85.9% vs. 78.9%; HR, 0.65), with an absolute benefit of 7.0%. Again, absolute benefit was more pronounced among women who had received prior chemotherapy (9.0%) or were younger than 35 years (13.1%).

The relative disease-free survival benefit of tamoxifen plus OFS over tamoxifen alone was similar across most subgroups stratified by disease characteristics, but patients with HER2-positive disease derived greater relative benefit from the combination as compared with their HER2-negative counterparts (P = .04 for interaction). “When we look at the combination of exemestane plus OFS versus tamoxifen, this heterogeneity is no longer seen,” Dr. Fleming noted.

In the entire trial population, there was no significant benefit of tamoxifen plus OFS over tamoxifen alone for distant recurrence-free interval and a small, significant absolute 1.9% gain in overall survival.

“The cohort who had elected to receive no prior chemotherapy did exceedingly well regardless of therapy,” she said, with little difference in overall survival across the three arms. “There were only 24 deaths total in this cohort, and 12 of those deaths were in the setting of no distant recurrence.”

On the other hand, among the women who received chemotherapy, there were significant absolute overall survival benefits of 4.3% with tamoxifen plus OFS and 2.1% with exemestane plus OFS, over tamoxifen alone. “This late emergence of an overall survival benefit is consistent with the time course of events in estrogen receptor–positive breast cancer,” Dr. Fleming commented.

The proportion of patients who stopped their oral endocrine therapy early was 22.5% with tamoxifen alone and 18.5% with tamoxifen plus OFS. (It was 27.8% with exemestane plus OFS.) “Almost a quarter of the patients on either tamoxifen arm were using extended oral endocrine therapy at 6 years or later prior to any disease progression. Only about 12% of patients in the exemestane group were doing so,” she noted.

There were more cases of endometrial cancer with tamoxifen alone than with tamoxifen plus OFS (7 vs. 4 cases). Thrombosis/embolism of grade 2-4 occurred in 2.2% of each group (and 0.9% of the exemestane plus OFS group). Musculoskeletal symptoms of grade 3 or 4 occurred in 6.7% of patients with tamoxifen alone and 5.9% with tamoxifen plus OFS, but 12.0% with exemestane plus OFS. Respective rates of osteoporosis grade 2-4 were 3.9%, 6.1%, and 11.9%.

“The addition of OFS to tamoxifen significantly improves disease-free survival at 8 years’ median follow-up, and disease-free survival benefits are further improved by the use of exemestane plus OFS,” Dr. Fleming summarized. “Follow-up, which is critically important given the long natural history of ER-positive disease, continues.”

Session attendee Matthew P. Goetz, MD, of the Mayo Clinic, Rochester, Minn., commented, “For the primary endpoint, I was looking at the tail for tamoxifen. It seemed that there was a relatively rapid drop-off between year 5 and this 8-year follow-up. Have you looked carefully to see whether there is a difference between those who stayed on their therapy versus those who went off it per protocol? That is, extended versus not extended? The question is whether there is a carry-over effect, if you will, that is different in those with OFS versus those not.”

“The percent who went on to extended therapy between the tamoxifen and the tamoxifen plus OFS was fairly similar,” Dr. Fleming replied. “But the answer is no, we have not yet done any sort of per protocol analysis.”

Session attendee Steven Vogl, MD, of Montefiore Medical Center, New York, commented, “I worry about your control group. I’m worried, first, how many of your tamoxifen patients lost their menses and became postmenopausal in those 5 years? And of those, why didn’t they switch to an aromatase inhibitor? Only 25% of the patients continued after the 5 years according to your slide, and all of those patients should either have stayed on tamoxifen or switched to an aromatase inhibitor, now probably for 2 years at least.”

“We have not yet looked at data for who became amenorrheic during treatment, although we have it. However, it’s certainly possible to become amenorrheic on tamoxifen and not be postmenopausal, and we didn’t regularly collect estradiol levels on any but the very small subset of women in the SOFT-S trial. So I don’t know that we have exactly the data that you’re looking for,” Dr. Fleming said. “Many of these women are obviously at very, very low risk and have done well with 5 years of tamoxifen alone, and I don’t know, even given current guidelines, that extended tamoxifen would add a lot to that.”

Finally, session attendee Richard Gray, professor of medical statistics at the University of Oxford (England), wondered, “What is the certainty that follow-up will happen? Because obviously, prolonged follow-up is expensive and there are controversies about that. But this would be the one study you would really want to have 15- and 20-year data on.”

“We are working very, very hard on that,” Dr. Fleming replied. “NCI granted additional funds to institutions for prolonging follow-up, and IBCSG has been ceaselessly working to look for funding to continue it. So I think it’s relatively certain that it will happen.”

Dr. Francis disclosed that she has received fees for non-CME services from AstraZeneca and has given an overseas lecture for Pfizer. Dr. Fleming disclosed that she had no relevant financial relationships with commercial interests. The trials received financial support from Pfizer and Ipsen.

SOURCES: Francis et al. SABCS Abstract GS4-02; Fleming et al. SABCS Abstract GS4-03
 

SAN ANTONIO – Adjuvant endocrine therapies improve outcomes of premenopausal breast cancer in the long term, with absolute benefit varying somewhat by therapy and by patient and disease characteristics, according to planned updates of a pair of pivotal phase 3 trials.

The trials – TEXT (Tamoxifen and Exemestane Trial) and SOFT (Suppression of Ovarian Function Trial) – are coordinated by the International Breast Cancer Study Group and together randomized more than 5,000 premenopausal women with early hormone receptor–positive breast cancer to 5 years of various types of adjuvant endocrine therapy. Their initial results, reported several years ago, form part of treatment guidelines that are used worldwide.

Clinical implications

These updates, along with other emerging data, can be used to optimize endocrine therapy for younger women with breast cancer, according to invited discussant Ann H. Partridge, MD, of Dana Farber Cancer Institute in Boston.

“For higher-risk disease, we should be considering OFS. At this point in time, I don’t think HER2 status alone should drive this decision,” she commented. “If you are getting OFS, what do we do, AI versus tamoxifen? Well, we do see a large improvement in disease-free survival [with AIs], so many women will want to use AIs. Yet tamoxifen is still reasonable, especially in light of the survival data.”

Data on switch strategies and extended-duration therapy are generally lacking at present for the premenopausal population, Dr. Partridge noted. “That’s something that we still need to extrapolate from data that’s predominantly in postmenopausal women.”

Another compelling question is whether OFS can be used instead of chemo for some patients. “We are increasingly recognizing that women with higher-risk anatomy and lower-risk biology having endocrine-responsive tumors may get more bang for the buck from the optimizing of hormonal therapy, and chemo may not add much,” she said.

Both short- and long-term toxicities of the various endocrine therapies and, for aromatase inhibitors, the potential for breakthrough (return of estradiol levels to premenopausal levels) also need to be considered, Dr. Partridge stressed. “And ultimately, patient preference and tolerance are key. After all, the best treatment is the one the patient will take.”

“We need to follow these women on TEXT and SOFT very long term. It would be a crime not to follow these women further out,” she maintained. “We need to conduct real-world comparative effectiveness research to understand the risks and benefits of OFS more fully in our survivors. Then, as we start to suppress more ovaries in more women with breast cancer, we need to be aware clinically of these risks, and we need to share this awareness with their primary care providers because we need to optimize in particular their cardiovascular risk factors, and screen and treat for potential comorbidities that they may be at higher risk for.”
 

Joint TEXT and SOFT update

Initial results of the joint TEXT and SOFT analysis, reported after a median follow-up of 5.7 years, showed that exemestane plus OFS was superior to tamoxifen plus OFS for the primary outcome, providing a significant 3.8% absolute gain in 5-year disease-free survival (N Engl J Med. 2014;371:107-18).

The updated joint analysis, now with a median follow-up of 9 years and based on data from 4,690 women, showed that the 8-year rate of disease-free survival was 86.8% with exemestane plus OFS versus 82.8% with tamoxifen plus OFS (hazard ratio, 0.77; P = .0006), for a similar absolute benefit of 4.0%, reported Prudence Francis, MD, of the University of Melbourne, head of Medical Oncology in the Breast Service at the Peter MacCallum Cancer Centre, Melbourne.

In stratified analysis, absolute benefit tended to be greater among women in TEXT who received chemotherapy (6.0%); intermediate among women in TEXT who did not receive chemotherapy (3.7%) and women in SOFT who received prior chemotherapy (3.7%); and less among women in SOFT who did not receive chemotherapy (1.9%).

Exemestane plus OFS was also superior to tamoxifen plus OFS in terms of breast cancer–free interval, with an absolute 4.1% benefit (P = .0002), and distant recurrence–free interval, with an absolute 2.1% benefit (P = .02). Overall survival did not differ significantly between arms.

Among the 86% of patients with HER2-negative disease, exemestane plus OFS netted an absolute disease-free survival gain of 5.4% and an absolute distant recurrence–free interval gain of 3.4%. There was a consistent relative treatment benefit across subgroups, but larger absolute benefit, on the order of 5%-9%, in women given chemotherapy and in those younger than 35 years.

“Results for the HER2-positive subgroup require further investigation,” Dr. Francis said. “The trials enrolled both before and after the routine use of adjuvant trastuzumab, and a significant proportion of the patients with HER2-positive breast cancer did not receive adjuvant HER2-targeted therapy.”

In the entire joint-analysis population, exemestane plus OFS was associated with higher rates of musculoskeletal events of grade 3 or 4 (11% vs. 6%) and osteoporosis of grade 2-4 (15% vs. 7%), while tamoxifen plus OFS was associated with a higher rate of thrombosis/embolism of grade 2-4 (2.3% vs. 1.2%) and more cases of endometrial cancer (9 vs. 4 cases). At 4 years, early discontinuation of oral endocrine therapy was greater for exemestane than for tamoxifen (25% vs. 19%).

“After longer follow-up, with a median of 9 years, the combined analysis results confirm a statistically significant improvement in disease outcomes with exemestane plus ovarian suppression. As is critical given the long natural history of estrogen receptor–positive breast cancer, follow-up in these trials is currently continuing,” Dr. Francis summarized.

“To optimally translate the observed absolute trial improvements into clinical practice, oncologists need to discuss and weigh the potential benefits and toxicities in each individual patient who is premenopausal with hormone receptor–positive breast cancer,” she recommended.

Session attendee Hope S. Rugo, MD, of the University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center, noted that exemestane had superior benefit despite the 25% rate of early discontinuation. “I wonder if one of the interpretations of that, given the toxicity of this therapy for very young women, is that we need some but maybe not so much. Maybe they don’t need 5 years altogether,” she said.

“The fact that they stopped their assigned endocrine therapy doesn’t mean that they didn’t continue any therapy. They may have switched over to tamoxifen or they may have decided they wanted to have a baby or there may have been many other things,” Dr. Francis replied, noting that analyses sorting out the reasons for early discontinuation are planned.

Session attendee Mark E. Sherman, MD, of the Mayo Clinic, Jacksonville, Fla., asked, “Do you have any ability to test for tamoxifen metabolites? It’s possible that a third to a half of patients got reduced benefit from that drug.”

Banked samples are available and a substudy is planned, according to Dr. Francis. “We haven’t got data on that yet, but yes, we are analyzing that.”
 

SOFT update

Initial results of the SOFT trial, reported after a median follow-up of 5.6 years, showed that adding OFS to tamoxifen did not significantly improve disease-free survival over tamoxifen alone in the entire trial population (N Engl J Med. 2015;372:436-46). However, there was benefit for women who received chemotherapy and remained premenopausal.

The updated SOFT analysis, now with a median follow-up of 8 years, focused mainly on the 1,018 women given tamoxifen alone and the 1,015 women given tamoxifen plus OFS. (Another 1,014 women were given exemestane plus OFS.)

“SOFT is now positive for its primary endpoint,” reported first author Gini Fleming, MD, director of the Medical Oncology Breast Program and medical oncology director of Gynecologic Oncology at University of Chicago Medicine. The 8-year disease-free survival rate was 83.2% with tamoxifen plus OFS, compared with 78.9% with tamoxifen alone (HR, 0.76; P = .009), corresponding to a 4.2% gain in this outcome. The relative benefit was identical whether patients had received chemotherapy or not, but absolute benefit was greater for those who had (5.3%), as well as for patients younger than 35 years (8.7%).

In addition, exemestane plus OFS was superior to tamoxifen alone (85.9% vs. 78.9%; HR, 0.65), with an absolute benefit of 7.0%. Again, absolute benefit was more pronounced among women who had received prior chemotherapy (9.0%) or were younger than 35 years (13.1%).

The relative disease-free survival benefit of tamoxifen plus OFS over tamoxifen alone was similar across most subgroups stratified by disease characteristics, but patients with HER2-positive disease derived greater relative benefit from the combination as compared with their HER2-negative counterparts (P = .04 for interaction). “When we look at the combination of exemestane plus OFS versus tamoxifen, this heterogeneity is no longer seen,” Dr. Fleming noted.

In the entire trial population, there was no significant benefit of tamoxifen plus OFS over tamoxifen alone for distant recurrence-free interval and a small, significant absolute 1.9% gain in overall survival.

“The cohort who had elected to receive no prior chemotherapy did exceedingly well regardless of therapy,” she said, with little difference in overall survival across the three arms. “There were only 24 deaths total in this cohort, and 12 of those deaths were in the setting of no distant recurrence.”

On the other hand, among the women who received chemotherapy, there were significant absolute overall survival benefits of 4.3% with tamoxifen plus OFS and 2.1% with exemestane plus OFS, over tamoxifen alone. “This late emergence of an overall survival benefit is consistent with the time course of events in estrogen receptor–positive breast cancer,” Dr. Fleming commented.

The proportion of patients who stopped their oral endocrine therapy early was 22.5% with tamoxifen alone and 18.5% with tamoxifen plus OFS. (It was 27.8% with exemestane plus OFS.) “Almost a quarter of the patients on either tamoxifen arm were using extended oral endocrine therapy at 6 years or later prior to any disease progression. Only about 12% of patients in the exemestane group were doing so,” she noted.

There were more cases of endometrial cancer with tamoxifen alone than with tamoxifen plus OFS (7 vs. 4 cases). Thrombosis/embolism of grade 2-4 occurred in 2.2% of each group (and 0.9% of the exemestane plus OFS group). Musculoskeletal symptoms of grade 3 or 4 occurred in 6.7% of patients with tamoxifen alone and 5.9% with tamoxifen plus OFS, but 12.0% with exemestane plus OFS. Respective rates of osteoporosis grade 2-4 were 3.9%, 6.1%, and 11.9%.

“The addition of OFS to tamoxifen significantly improves disease-free survival at 8 years’ median follow-up, and disease-free survival benefits are further improved by the use of exemestane plus OFS,” Dr. Fleming summarized. “Follow-up, which is critically important given the long natural history of ER-positive disease, continues.”

Session attendee Matthew P. Goetz, MD, of the Mayo Clinic, Rochester, Minn., commented, “For the primary endpoint, I was looking at the tail for tamoxifen. It seemed that there was a relatively rapid drop-off between year 5 and this 8-year follow-up. Have you looked carefully to see whether there is a difference between those who stayed on their therapy versus those who went off it per protocol? That is, extended versus not extended? The question is whether there is a carry-over effect, if you will, that is different in those with OFS versus those not.”

“The percent who went on to extended therapy between the tamoxifen and the tamoxifen plus OFS was fairly similar,” Dr. Fleming replied. “But the answer is no, we have not yet done any sort of per protocol analysis.”

Session attendee Steven Vogl, MD, of Montefiore Medical Center, New York, commented, “I worry about your control group. I’m worried, first, how many of your tamoxifen patients lost their menses and became postmenopausal in those 5 years? And of those, why didn’t they switch to an aromatase inhibitor? Only 25% of the patients continued after the 5 years according to your slide, and all of those patients should either have stayed on tamoxifen or switched to an aromatase inhibitor, now probably for 2 years at least.”

“We have not yet looked at data for who became amenorrheic during treatment, although we have it. However, it’s certainly possible to become amenorrheic on tamoxifen and not be postmenopausal, and we didn’t regularly collect estradiol levels on any but the very small subset of women in the SOFT-S trial. So I don’t know that we have exactly the data that you’re looking for,” Dr. Fleming said. “Many of these women are obviously at very, very low risk and have done well with 5 years of tamoxifen alone, and I don’t know, even given current guidelines, that extended tamoxifen would add a lot to that.”

Finally, session attendee Richard Gray, professor of medical statistics at the University of Oxford (England), wondered, “What is the certainty that follow-up will happen? Because obviously, prolonged follow-up is expensive and there are controversies about that. But this would be the one study you would really want to have 15- and 20-year data on.”

“We are working very, very hard on that,” Dr. Fleming replied. “NCI granted additional funds to institutions for prolonging follow-up, and IBCSG has been ceaselessly working to look for funding to continue it. So I think it’s relatively certain that it will happen.”

Dr. Francis disclosed that she has received fees for non-CME services from AstraZeneca and has given an overseas lecture for Pfizer. Dr. Fleming disclosed that she had no relevant financial relationships with commercial interests. The trials received financial support from Pfizer and Ipsen.

SOURCES: Francis et al. SABCS Abstract GS4-02; Fleming et al. SABCS Abstract GS4-03
 

SAN ANTONIO – Adjuvant endocrine therapies improve outcomes of premenopausal breast cancer in the long term, with absolute benefit varying somewhat by therapy and by patient and disease characteristics, according to planned updates of a pair of pivotal phase 3 trials.

The trials – TEXT (Tamoxifen and Exemestane Trial) and SOFT (Suppression of Ovarian Function Trial) – are coordinated by the International Breast Cancer Study Group and together randomized more than 5,000 premenopausal women with early hormone receptor–positive breast cancer to 5 years of various types of adjuvant endocrine therapy. Their initial results, reported several years ago, form part of treatment guidelines that are used worldwide.

Clinical implications

These updates, along with other emerging data, can be used to optimize endocrine therapy for younger women with breast cancer, according to invited discussant Ann H. Partridge, MD, of Dana Farber Cancer Institute in Boston.

“For higher-risk disease, we should be considering OFS. At this point in time, I don’t think HER2 status alone should drive this decision,” she commented. “If you are getting OFS, what do we do, AI versus tamoxifen? Well, we do see a large improvement in disease-free survival [with AIs], so many women will want to use AIs. Yet tamoxifen is still reasonable, especially in light of the survival data.”

Data on switch strategies and extended-duration therapy are generally lacking at present for the premenopausal population, Dr. Partridge noted. “That’s something that we still need to extrapolate from data that’s predominantly in postmenopausal women.”

Another compelling question is whether OFS can be used instead of chemo for some patients. “We are increasingly recognizing that women with higher-risk anatomy and lower-risk biology having endocrine-responsive tumors may get more bang for the buck from the optimizing of hormonal therapy, and chemo may not add much,” she said.

Both short- and long-term toxicities of the various endocrine therapies and, for aromatase inhibitors, the potential for breakthrough (return of estradiol levels to premenopausal levels) also need to be considered, Dr. Partridge stressed. “And ultimately, patient preference and tolerance are key. After all, the best treatment is the one the patient will take.”

“We need to follow these women on TEXT and SOFT very long term. It would be a crime not to follow these women further out,” she maintained. “We need to conduct real-world comparative effectiveness research to understand the risks and benefits of OFS more fully in our survivors. Then, as we start to suppress more ovaries in more women with breast cancer, we need to be aware clinically of these risks, and we need to share this awareness with their primary care providers because we need to optimize in particular their cardiovascular risk factors, and screen and treat for potential comorbidities that they may be at higher risk for.”
 

Joint TEXT and SOFT update

Initial results of the joint TEXT and SOFT analysis, reported after a median follow-up of 5.7 years, showed that exemestane plus OFS was superior to tamoxifen plus OFS for the primary outcome, providing a significant 3.8% absolute gain in 5-year disease-free survival (N Engl J Med. 2014;371:107-18).

The updated joint analysis, now with a median follow-up of 9 years and based on data from 4,690 women, showed that the 8-year rate of disease-free survival was 86.8% with exemestane plus OFS versus 82.8% with tamoxifen plus OFS (hazard ratio, 0.77; P = .0006), for a similar absolute benefit of 4.0%, reported Prudence Francis, MD, of the University of Melbourne, head of Medical Oncology in the Breast Service at the Peter MacCallum Cancer Centre, Melbourne.

In stratified analysis, absolute benefit tended to be greater among women in TEXT who received chemotherapy (6.0%); intermediate among women in TEXT who did not receive chemotherapy (3.7%) and women in SOFT who received prior chemotherapy (3.7%); and less among women in SOFT who did not receive chemotherapy (1.9%).

Exemestane plus OFS was also superior to tamoxifen plus OFS in terms of breast cancer–free interval, with an absolute 4.1% benefit (P = .0002), and distant recurrence–free interval, with an absolute 2.1% benefit (P = .02). Overall survival did not differ significantly between arms.

Among the 86% of patients with HER2-negative disease, exemestane plus OFS netted an absolute disease-free survival gain of 5.4% and an absolute distant recurrence–free interval gain of 3.4%. There was a consistent relative treatment benefit across subgroups, but larger absolute benefit, on the order of 5%-9%, in women given chemotherapy and in those younger than 35 years.

“Results for the HER2-positive subgroup require further investigation,” Dr. Francis said. “The trials enrolled both before and after the routine use of adjuvant trastuzumab, and a significant proportion of the patients with HER2-positive breast cancer did not receive adjuvant HER2-targeted therapy.”

In the entire joint-analysis population, exemestane plus OFS was associated with higher rates of musculoskeletal events of grade 3 or 4 (11% vs. 6%) and osteoporosis of grade 2-4 (15% vs. 7%), while tamoxifen plus OFS was associated with a higher rate of thrombosis/embolism of grade 2-4 (2.3% vs. 1.2%) and more cases of endometrial cancer (9 vs. 4 cases). At 4 years, early discontinuation of oral endocrine therapy was greater for exemestane than for tamoxifen (25% vs. 19%).

“After longer follow-up, with a median of 9 years, the combined analysis results confirm a statistically significant improvement in disease outcomes with exemestane plus ovarian suppression. As is critical given the long natural history of estrogen receptor–positive breast cancer, follow-up in these trials is currently continuing,” Dr. Francis summarized.

“To optimally translate the observed absolute trial improvements into clinical practice, oncologists need to discuss and weigh the potential benefits and toxicities in each individual patient who is premenopausal with hormone receptor–positive breast cancer,” she recommended.

Session attendee Hope S. Rugo, MD, of the University of California, San Francisco, Helen Diller Family Comprehensive Cancer Center, noted that exemestane had superior benefit despite the 25% rate of early discontinuation. “I wonder if one of the interpretations of that, given the toxicity of this therapy for very young women, is that we need some but maybe not so much. Maybe they don’t need 5 years altogether,” she said.

“The fact that they stopped their assigned endocrine therapy doesn’t mean that they didn’t continue any therapy. They may have switched over to tamoxifen or they may have decided they wanted to have a baby or there may have been many other things,” Dr. Francis replied, noting that analyses sorting out the reasons for early discontinuation are planned.

Session attendee Mark E. Sherman, MD, of the Mayo Clinic, Jacksonville, Fla., asked, “Do you have any ability to test for tamoxifen metabolites? It’s possible that a third to a half of patients got reduced benefit from that drug.”

Banked samples are available and a substudy is planned, according to Dr. Francis. “We haven’t got data on that yet, but yes, we are analyzing that.”
 

SOFT update

Initial results of the SOFT trial, reported after a median follow-up of 5.6 years, showed that adding OFS to tamoxifen did not significantly improve disease-free survival over tamoxifen alone in the entire trial population (N Engl J Med. 2015;372:436-46). However, there was benefit for women who received chemotherapy and remained premenopausal.

The updated SOFT analysis, now with a median follow-up of 8 years, focused mainly on the 1,018 women given tamoxifen alone and the 1,015 women given tamoxifen plus OFS. (Another 1,014 women were given exemestane plus OFS.)

“SOFT is now positive for its primary endpoint,” reported first author Gini Fleming, MD, director of the Medical Oncology Breast Program and medical oncology director of Gynecologic Oncology at University of Chicago Medicine. The 8-year disease-free survival rate was 83.2% with tamoxifen plus OFS, compared with 78.9% with tamoxifen alone (HR, 0.76; P = .009), corresponding to a 4.2% gain in this outcome. The relative benefit was identical whether patients had received chemotherapy or not, but absolute benefit was greater for those who had (5.3%), as well as for patients younger than 35 years (8.7%).

In addition, exemestane plus OFS was superior to tamoxifen alone (85.9% vs. 78.9%; HR, 0.65), with an absolute benefit of 7.0%. Again, absolute benefit was more pronounced among women who had received prior chemotherapy (9.0%) or were younger than 35 years (13.1%).

The relative disease-free survival benefit of tamoxifen plus OFS over tamoxifen alone was similar across most subgroups stratified by disease characteristics, but patients with HER2-positive disease derived greater relative benefit from the combination as compared with their HER2-negative counterparts (P = .04 for interaction). “When we look at the combination of exemestane plus OFS versus tamoxifen, this heterogeneity is no longer seen,” Dr. Fleming noted.

In the entire trial population, there was no significant benefit of tamoxifen plus OFS over tamoxifen alone for distant recurrence-free interval and a small, significant absolute 1.9% gain in overall survival.

“The cohort who had elected to receive no prior chemotherapy did exceedingly well regardless of therapy,” she said, with little difference in overall survival across the three arms. “There were only 24 deaths total in this cohort, and 12 of those deaths were in the setting of no distant recurrence.”

On the other hand, among the women who received chemotherapy, there were significant absolute overall survival benefits of 4.3% with tamoxifen plus OFS and 2.1% with exemestane plus OFS, over tamoxifen alone. “This late emergence of an overall survival benefit is consistent with the time course of events in estrogen receptor–positive breast cancer,” Dr. Fleming commented.

The proportion of patients who stopped their oral endocrine therapy early was 22.5% with tamoxifen alone and 18.5% with tamoxifen plus OFS. (It was 27.8% with exemestane plus OFS.) “Almost a quarter of the patients on either tamoxifen arm were using extended oral endocrine therapy at 6 years or later prior to any disease progression. Only about 12% of patients in the exemestane group were doing so,” she noted.

There were more cases of endometrial cancer with tamoxifen alone than with tamoxifen plus OFS (7 vs. 4 cases). Thrombosis/embolism of grade 2-4 occurred in 2.2% of each group (and 0.9% of the exemestane plus OFS group). Musculoskeletal symptoms of grade 3 or 4 occurred in 6.7% of patients with tamoxifen alone and 5.9% with tamoxifen plus OFS, but 12.0% with exemestane plus OFS. Respective rates of osteoporosis grade 2-4 were 3.9%, 6.1%, and 11.9%.

“The addition of OFS to tamoxifen significantly improves disease-free survival at 8 years’ median follow-up, and disease-free survival benefits are further improved by the use of exemestane plus OFS,” Dr. Fleming summarized. “Follow-up, which is critically important given the long natural history of ER-positive disease, continues.”

Session attendee Matthew P. Goetz, MD, of the Mayo Clinic, Rochester, Minn., commented, “For the primary endpoint, I was looking at the tail for tamoxifen. It seemed that there was a relatively rapid drop-off between year 5 and this 8-year follow-up. Have you looked carefully to see whether there is a difference between those who stayed on their therapy versus those who went off it per protocol? That is, extended versus not extended? The question is whether there is a carry-over effect, if you will, that is different in those with OFS versus those not.”

“The percent who went on to extended therapy between the tamoxifen and the tamoxifen plus OFS was fairly similar,” Dr. Fleming replied. “But the answer is no, we have not yet done any sort of per protocol analysis.”

Session attendee Steven Vogl, MD, of Montefiore Medical Center, New York, commented, “I worry about your control group. I’m worried, first, how many of your tamoxifen patients lost their menses and became postmenopausal in those 5 years? And of those, why didn’t they switch to an aromatase inhibitor? Only 25% of the patients continued after the 5 years according to your slide, and all of those patients should either have stayed on tamoxifen or switched to an aromatase inhibitor, now probably for 2 years at least.”

“We have not yet looked at data for who became amenorrheic during treatment, although we have it. However, it’s certainly possible to become amenorrheic on tamoxifen and not be postmenopausal, and we didn’t regularly collect estradiol levels on any but the very small subset of women in the SOFT-S trial. So I don’t know that we have exactly the data that you’re looking for,” Dr. Fleming said. “Many of these women are obviously at very, very low risk and have done well with 5 years of tamoxifen alone, and I don’t know, even given current guidelines, that extended tamoxifen would add a lot to that.”

Finally, session attendee Richard Gray, professor of medical statistics at the University of Oxford (England), wondered, “What is the certainty that follow-up will happen? Because obviously, prolonged follow-up is expensive and there are controversies about that. But this would be the one study you would really want to have 15- and 20-year data on.”

“We are working very, very hard on that,” Dr. Fleming replied. “NCI granted additional funds to institutions for prolonging follow-up, and IBCSG has been ceaselessly working to look for funding to continue it. So I think it’s relatively certain that it will happen.”

Dr. Francis disclosed that she has received fees for non-CME services from AstraZeneca and has given an overseas lecture for Pfizer. Dr. Fleming disclosed that she had no relevant financial relationships with commercial interests. The trials received financial support from Pfizer and Ipsen.

SOURCES: Francis et al. SABCS Abstract GS4-02; Fleming et al. SABCS Abstract GS4-03
 

SAN ANTONIO – A new prognostic tool that uses four clinical and pathological variables may help to guide decisions about extending adjuvant endocrine therapy for postmenopausal women with estrogen receptor–positive (ER+) breast cancer, according to a study reported at the San Antonio Breast Cancer Symposium.

ER+ breast cancer is well known for recurring long after endocrine therapy stops, but the risk varies widely, ranging from 10% to 40% (N Engl J Med. 2017;377:1836-46), noted lead investigator Ivana Sestak, MS, PhD, a lecturer in medical statistics at the Queen Mary University of London. “A few trials have shown that extended endocrine therapy can reduce the risk of recurrence, but careful assessment of potential side effects and actual risk of developing a late distant recurrence is essential,” she said.

Courtesy of Dr. Sestak

Study details

The investigators developed and trained the new tool using data from 4,735 women from the ATAC trial. They then validated the tool using data from 6,711 women from the BIG 1-98 trial.

The final CTS5 model contained four clinical variables, Dr. Sestak reported: number of involved nodes, size of the tumor, grade of the tumor, and age of the patient.

In the ATAC population, the CTS5 model did a better job than the original CTS0 model of predicting late distant recurrence. CTS5 improved the prediction of late distant recurrence by a factor of 2.47, whereas CTS0 improved the predictive value by a factor of 2.04. The CTS5 model performed similarly well regardless of whether patients had received chemotherapy.

In the BIG 1-98 population, the findings were much the same: The CTS5 model improved prediction of late distant recurrence by 2.07, while the CTS0 model improved prediction of late distant recurrence by 1.84. Performance of the CTS5 model was again similarly good regardless of whether patients had received chemotherapy.

Observed rates of distant recurrence between years 5 and 10 were similar in the ATAC and BIG 1-98 populations for the CTS5-defined low-risk group (2.5% and 3.0%, respectively), intermediate-risk group (7.7% and 6.9%), and the high-risk group (20.3% and 17.3%).

When the two trials’ populations were combined, the observed rate was 3.0% in the CTS5-defined low-risk group, 7.3% in the intermediate-risk group, and 18.9% in the high-risk group.

In addition, the main results held up among all node-negative women combined and among all women who had between one and three positive nodes combined. “For women with four or more positive lymph nodes, the CTS5 was not informative and categorized virtually all women into the high-risk group,” Dr. Sestak noted.

The investigators did not look at whether local or regional recurrences modulated the risk of late distant recurrence, she said. However, women who had experienced isolated local recurrence during the first 5 years would have been included in analysis.

“A strength of our study is that we used clinicopathological parameters that are measured in all breast cancer patients, and there is no need for further testing,” noted Dr. Sestak, who disclosed that she has received fees for advisory boards and lectures from Myriad Genetics.

On the other hand, it is unclear how the CTS5 would perform among premenopausal women and among women with HER2-positive disease given that two trials took place before routine HER2 testing and HER2-directed therapy were used.

SOURCE: Sestak I et al. SABCS 2017 Abstract GS6-01.

SAN ANTONIO – A new prognostic tool that uses four clinical and pathological variables may help to guide decisions about extending adjuvant endocrine therapy for postmenopausal women with estrogen receptor–positive (ER+) breast cancer, according to a study reported at the San Antonio Breast Cancer Symposium.

ER+ breast cancer is well known for recurring long after endocrine therapy stops, but the risk varies widely, ranging from 10% to 40% (N Engl J Med. 2017;377:1836-46), noted lead investigator Ivana Sestak, MS, PhD, a lecturer in medical statistics at the Queen Mary University of London. “A few trials have shown that extended endocrine therapy can reduce the risk of recurrence, but careful assessment of potential side effects and actual risk of developing a late distant recurrence is essential,” she said.

Courtesy of Dr. Sestak

Study details

The investigators developed and trained the new tool using data from 4,735 women from the ATAC trial. They then validated the tool using data from 6,711 women from the BIG 1-98 trial.

The final CTS5 model contained four clinical variables, Dr. Sestak reported: number of involved nodes, size of the tumor, grade of the tumor, and age of the patient.

In the ATAC population, the CTS5 model did a better job than the original CTS0 model of predicting late distant recurrence. CTS5 improved the prediction of late distant recurrence by a factor of 2.47, whereas CTS0 improved the predictive value by a factor of 2.04. The CTS5 model performed similarly well regardless of whether patients had received chemotherapy.

In the BIG 1-98 population, the findings were much the same: The CTS5 model improved prediction of late distant recurrence by 2.07, while the CTS0 model improved prediction of late distant recurrence by 1.84. Performance of the CTS5 model was again similarly good regardless of whether patients had received chemotherapy.

Observed rates of distant recurrence between years 5 and 10 were similar in the ATAC and BIG 1-98 populations for the CTS5-defined low-risk group (2.5% and 3.0%, respectively), intermediate-risk group (7.7% and 6.9%), and the high-risk group (20.3% and 17.3%).

When the two trials’ populations were combined, the observed rate was 3.0% in the CTS5-defined low-risk group, 7.3% in the intermediate-risk group, and 18.9% in the high-risk group.

In addition, the main results held up among all node-negative women combined and among all women who had between one and three positive nodes combined. “For women with four or more positive lymph nodes, the CTS5 was not informative and categorized virtually all women into the high-risk group,” Dr. Sestak noted.

The investigators did not look at whether local or regional recurrences modulated the risk of late distant recurrence, she said. However, women who had experienced isolated local recurrence during the first 5 years would have been included in analysis.

“A strength of our study is that we used clinicopathological parameters that are measured in all breast cancer patients, and there is no need for further testing,” noted Dr. Sestak, who disclosed that she has received fees for advisory boards and lectures from Myriad Genetics.

On the other hand, it is unclear how the CTS5 would perform among premenopausal women and among women with HER2-positive disease given that two trials took place before routine HER2 testing and HER2-directed therapy were used.

SOURCE: Sestak I et al. SABCS 2017 Abstract GS6-01.

SAN ANTONIO – A new prognostic tool that uses four clinical and pathological variables may help to guide decisions about extending adjuvant endocrine therapy for postmenopausal women with estrogen receptor–positive (ER+) breast cancer, according to a study reported at the San Antonio Breast Cancer Symposium.

ER+ breast cancer is well known for recurring long after endocrine therapy stops, but the risk varies widely, ranging from 10% to 40% (N Engl J Med. 2017;377:1836-46), noted lead investigator Ivana Sestak, MS, PhD, a lecturer in medical statistics at the Queen Mary University of London. “A few trials have shown that extended endocrine therapy can reduce the risk of recurrence, but careful assessment of potential side effects and actual risk of developing a late distant recurrence is essential,” she said.

Courtesy of Dr. Sestak

Study details

The investigators developed and trained the new tool using data from 4,735 women from the ATAC trial. They then validated the tool using data from 6,711 women from the BIG 1-98 trial.

The final CTS5 model contained four clinical variables, Dr. Sestak reported: number of involved nodes, size of the tumor, grade of the tumor, and age of the patient.

In the ATAC population, the CTS5 model did a better job than the original CTS0 model of predicting late distant recurrence. CTS5 improved the prediction of late distant recurrence by a factor of 2.47, whereas CTS0 improved the predictive value by a factor of 2.04. The CTS5 model performed similarly well regardless of whether patients had received chemotherapy.

In the BIG 1-98 population, the findings were much the same: The CTS5 model improved prediction of late distant recurrence by 2.07, while the CTS0 model improved prediction of late distant recurrence by 1.84. Performance of the CTS5 model was again similarly good regardless of whether patients had received chemotherapy.

Observed rates of distant recurrence between years 5 and 10 were similar in the ATAC and BIG 1-98 populations for the CTS5-defined low-risk group (2.5% and 3.0%, respectively), intermediate-risk group (7.7% and 6.9%), and the high-risk group (20.3% and 17.3%).

When the two trials’ populations were combined, the observed rate was 3.0% in the CTS5-defined low-risk group, 7.3% in the intermediate-risk group, and 18.9% in the high-risk group.

In addition, the main results held up among all node-negative women combined and among all women who had between one and three positive nodes combined. “For women with four or more positive lymph nodes, the CTS5 was not informative and categorized virtually all women into the high-risk group,” Dr. Sestak noted.

The investigators did not look at whether local or regional recurrences modulated the risk of late distant recurrence, she said. However, women who had experienced isolated local recurrence during the first 5 years would have been included in analysis.

“A strength of our study is that we used clinicopathological parameters that are measured in all breast cancer patients, and there is no need for further testing,” noted Dr. Sestak, who disclosed that she has received fees for advisory boards and lectures from Myriad Genetics.

On the other hand, it is unclear how the CTS5 would perform among premenopausal women and among women with HER2-positive disease given that two trials took place before routine HER2 testing and HER2-directed therapy were used.

SOURCE: Sestak I et al. SABCS 2017 Abstract GS6-01.

SAN ANTONIO – The results of the EndoPredict test appear to predict tumor response in patients with early hormone receptor–positive, HER2-negative breast cancer given neoadjuvant therapy, based on results of a study conducted by the Austrian Breast & Colorectal Cancer Study Group (ABCSG).

“Very good tumor shrinkage in estrogen receptor–positive, HER2-negative disease is going to happen only in a minority of patients, and biomarkers that would predict excellent tumor shrinkage are an unmet medical need,” commented lead investigator Peter Dubsky, MD, PhD, who is head of the Breast Center at Hirslanden Klinik St. Anna, Lucerne, Switzerland. “As a surgeon, that would help me to predict breast conservation at diagnosis, but as a surgical oncologist, I would also recognize that tumor response is an important component of future survival.”

SABCS/Scott Morgan 2017

Study details

ABCSG 34 was a randomized phase 2 trial testing addition of the cancer vaccine tecemotide (Stimuvax) to neoadjuvant standard of care among patients with HER2-negative early breast cancer.

Dr. Dubsky and coinvestigators restricted analyses to patients with hormone receptor–positive disease who, depending on clinical and pathologic factors, received neoadjuvant chemotherapy (eight cycles of epirubicin-cyclophosphamide and docetaxel) or neoadjuvant endocrine therapy (6 months of letrozole [Femara]) as standard of care. They were then randomized to additionally receive tecemotide or not before undergoing surgery.

Overall, 25% of the 134 patients in the neoadjuvant chemotherapy group had a good tumor response, defined as pathologic complete response in both breast and nodes (RCB of 0) or minimal residual disease (RCB of I).

Higher EndoPredict score was associated with greater likelihood of good response to chemotherapy. EndoPredict risk group (high vs. low) had a negative predictive value of 100%, a positive predictive value of 26.4%, a true-positive rate of 100%, and a true-negative rate of 8.9% for predicting response (P = .112).

Area under the receiver operating characteristic curve was 0.736.

In a multivariate model, EndoPredict score as a continuous variable was not an independent predictor of response. “The good response was largely driven by covariates that included cell proliferation, and it was Ki-67 that was significant,” Dr. Dubsky noted.

Overall, 18% of the 83 patients in the neoadjuvant endocrine therapy group had a good tumor response (RCB of 0 or I). Here, lower EndoPredict score was associated with greater likelihood of good response. EndoPredict risk group (high vs. low) had a negative predictive value of 92.3%, a positive predictive value of 27.3%, a true-positive rate of 80.0%, and a true-negative rate of 52.9% for predicting response (P = .024). Area under the curve was 0.726.

In a multivariate model here, EndoPredict score as a continuous variable, its estrogen receptor–signaling/differentiation component, and Ki-67 did not independently predict response. “It was maybe a bit surprising that T stage was the strongest factor, possibly indicating that we should have simply treated those women longer than 6 months,” Dr. Dubsky commented. The EndoPredict proliferation component was also a significant predictor.

“Possibly, the very narrow distribution of Ki-67 [among patients given neoendocrine therapy] may have prevented this factor from playing a bigger role in this particular model,” he speculated.

Dr. Dubsky disclosed that he receives consulting fees from Myriad, the maker of EndoPredict, and from Cepheid, Nanostring, and Amgen.

SOURCE: Dubsky P et al. SABCS 2017 Abstract GS6-04.

op@frontlinemedcom.com

SAN ANTONIO – The results of the EndoPredict test appear to predict tumor response in patients with early hormone receptor–positive, HER2-negative breast cancer given neoadjuvant therapy, based on results of a study conducted by the Austrian Breast & Colorectal Cancer Study Group (ABCSG).

“Very good tumor shrinkage in estrogen receptor–positive, HER2-negative disease is going to happen only in a minority of patients, and biomarkers that would predict excellent tumor shrinkage are an unmet medical need,” commented lead investigator Peter Dubsky, MD, PhD, who is head of the Breast Center at Hirslanden Klinik St. Anna, Lucerne, Switzerland. “As a surgeon, that would help me to predict breast conservation at diagnosis, but as a surgical oncologist, I would also recognize that tumor response is an important component of future survival.”

SABCS/Scott Morgan 2017

Study details

ABCSG 34 was a randomized phase 2 trial testing addition of the cancer vaccine tecemotide (Stimuvax) to neoadjuvant standard of care among patients with HER2-negative early breast cancer.

Dr. Dubsky and coinvestigators restricted analyses to patients with hormone receptor–positive disease who, depending on clinical and pathologic factors, received neoadjuvant chemotherapy (eight cycles of epirubicin-cyclophosphamide and docetaxel) or neoadjuvant endocrine therapy (6 months of letrozole [Femara]) as standard of care. They were then randomized to additionally receive tecemotide or not before undergoing surgery.

Overall, 25% of the 134 patients in the neoadjuvant chemotherapy group had a good tumor response, defined as pathologic complete response in both breast and nodes (RCB of 0) or minimal residual disease (RCB of I).

Higher EndoPredict score was associated with greater likelihood of good response to chemotherapy. EndoPredict risk group (high vs. low) had a negative predictive value of 100%, a positive predictive value of 26.4%, a true-positive rate of 100%, and a true-negative rate of 8.9% for predicting response (P = .112).

Area under the receiver operating characteristic curve was 0.736.

In a multivariate model, EndoPredict score as a continuous variable was not an independent predictor of response. “The good response was largely driven by covariates that included cell proliferation, and it was Ki-67 that was significant,” Dr. Dubsky noted.

Overall, 18% of the 83 patients in the neoadjuvant endocrine therapy group had a good tumor response (RCB of 0 or I). Here, lower EndoPredict score was associated with greater likelihood of good response. EndoPredict risk group (high vs. low) had a negative predictive value of 92.3%, a positive predictive value of 27.3%, a true-positive rate of 80.0%, and a true-negative rate of 52.9% for predicting response (P = .024). Area under the curve was 0.726.

In a multivariate model here, EndoPredict score as a continuous variable, its estrogen receptor–signaling/differentiation component, and Ki-67 did not independently predict response. “It was maybe a bit surprising that T stage was the strongest factor, possibly indicating that we should have simply treated those women longer than 6 months,” Dr. Dubsky commented. The EndoPredict proliferation component was also a significant predictor.

“Possibly, the very narrow distribution of Ki-67 [among patients given neoendocrine therapy] may have prevented this factor from playing a bigger role in this particular model,” he speculated.

Dr. Dubsky disclosed that he receives consulting fees from Myriad, the maker of EndoPredict, and from Cepheid, Nanostring, and Amgen.

SOURCE: Dubsky P et al. SABCS 2017 Abstract GS6-04.

op@frontlinemedcom.com

SAN ANTONIO – The results of the EndoPredict test appear to predict tumor response in patients with early hormone receptor–positive, HER2-negative breast cancer given neoadjuvant therapy, based on results of a study conducted by the Austrian Breast & Colorectal Cancer Study Group (ABCSG).

“Very good tumor shrinkage in estrogen receptor–positive, HER2-negative disease is going to happen only in a minority of patients, and biomarkers that would predict excellent tumor shrinkage are an unmet medical need,” commented lead investigator Peter Dubsky, MD, PhD, who is head of the Breast Center at Hirslanden Klinik St. Anna, Lucerne, Switzerland. “As a surgeon, that would help me to predict breast conservation at diagnosis, but as a surgical oncologist, I would also recognize that tumor response is an important component of future survival.”

SABCS/Scott Morgan 2017

Study details

ABCSG 34 was a randomized phase 2 trial testing addition of the cancer vaccine tecemotide (Stimuvax) to neoadjuvant standard of care among patients with HER2-negative early breast cancer.

Dr. Dubsky and coinvestigators restricted analyses to patients with hormone receptor–positive disease who, depending on clinical and pathologic factors, received neoadjuvant chemotherapy (eight cycles of epirubicin-cyclophosphamide and docetaxel) or neoadjuvant endocrine therapy (6 months of letrozole [Femara]) as standard of care. They were then randomized to additionally receive tecemotide or not before undergoing surgery.

Overall, 25% of the 134 patients in the neoadjuvant chemotherapy group had a good tumor response, defined as pathologic complete response in both breast and nodes (RCB of 0) or minimal residual disease (RCB of I).

Higher EndoPredict score was associated with greater likelihood of good response to chemotherapy. EndoPredict risk group (high vs. low) had a negative predictive value of 100%, a positive predictive value of 26.4%, a true-positive rate of 100%, and a true-negative rate of 8.9% for predicting response (P = .112).

Area under the receiver operating characteristic curve was 0.736.

In a multivariate model, EndoPredict score as a continuous variable was not an independent predictor of response. “The good response was largely driven by covariates that included cell proliferation, and it was Ki-67 that was significant,” Dr. Dubsky noted.

Overall, 18% of the 83 patients in the neoadjuvant endocrine therapy group had a good tumor response (RCB of 0 or I). Here, lower EndoPredict score was associated with greater likelihood of good response. EndoPredict risk group (high vs. low) had a negative predictive value of 92.3%, a positive predictive value of 27.3%, a true-positive rate of 80.0%, and a true-negative rate of 52.9% for predicting response (P = .024). Area under the curve was 0.726.

In a multivariate model here, EndoPredict score as a continuous variable, its estrogen receptor–signaling/differentiation component, and Ki-67 did not independently predict response. “It was maybe a bit surprising that T stage was the strongest factor, possibly indicating that we should have simply treated those women longer than 6 months,” Dr. Dubsky commented. The EndoPredict proliferation component was also a significant predictor.

“Possibly, the very narrow distribution of Ki-67 [among patients given neoendocrine therapy] may have prevented this factor from playing a bigger role in this particular model,” he speculated.

Dr. Dubsky disclosed that he receives consulting fees from Myriad, the maker of EndoPredict, and from Cepheid, Nanostring, and Amgen.

SOURCE: Dubsky P et al. SABCS 2017 Abstract GS6-04.

op@frontlinemedcom.com

SAN ANTONIO – A margin width beyond ‘no tumor on ink’ may reduce local recurrence in certain subsets of patients undergoing breast-conserving treatment for early-stage breast cancer, according to findings from a meta-analysis.

“Further prospective studies are required to validate the appropriate margin width,” study author Frank A. Vicini, MD, of 21st Century Oncology/Michigan Healthcare Professionals in Farmington Hills, Michigan, said at the San Antonio Breast Cancer Symposium.

Dr. Vicini pointed out that the medical community has been addressing the question of “what is the appropriate margin for breast conserving therapy” for about 3 or 4 decades. A meta-analysis of 33 studies (Ann Surg Oncol. 2014 Mar;21[3]:717-30. doi: 10.1245/s10434-014-3480-5) showed that wider margins are unlikely to have a substantial benefit over “no tumor on ink.”

The results of the meta-analysis led to guidelines published by the Society of Surgical Oncology–American Society for Radiation Oncology that supported those conclusions.

“So the question now is that with additional patients and additional modeling, is this conclusion still correct?” Dr. Vicini said.

The 2014 meta-analysis had significant limitations, and to address them, Dr. Vicini and his colleagues conducted an updated analysis of all available data that included 31 of the initial studies. However, stricter criteria were used for inclusion into their review. The authors reviewed all studies published between 1995 and 2016 that had a minimum follow-up of 50 months, and that included explicit pathologic definitions of margin status and local recurrence in relation to margin status.

The final meta-analysis included 55,302 patients (74% T1 tumors; 72% node-negative disease) from a total of 38 studies, and the median follow up was 7.2 years.

The analysis used three generalized linear mixed models for the outcome of local recurrence, and random effects for study and fixed effects for various patient and study characteristics.

In model 1, all patients with at or equal margin width were compared with those who had wider margins. Model 2 examined the impact of margin width “range” as opposed to a set margin width of 0 mm to 2 mm, 2 mm to 5 mm, or greater than 5 mm. Model 3 divided margin distance by cut points of –1 mm, 2 mm, and 5 mm.

The crude rate of local recurrence was 10.3% for patients with positive margins versus 3.8% for those with negative margins that were defined as no tumor on ink or wider (P less than .001). Local recurrence rates declined as the margin distance increased: 7.2% for patients with margins 0-2 mm, 3.6% for margins of 2-5 mm, and 3.2% for margins wider than 5 mm (P less than .001 for each). The use of endocrine therapy and increasing median study year were associated with decreased rates of local recurrence in univariate models but not in multivariable analyses.

For local recurrence in model 1, a benefit for wider margins was observed, with the greatest benefit seen at 1 mm. The odds ratio (OR) for local recurrence for negative vs. close/positive margins was 0.46 (95% confidence interval, 0.4-0.53) for margins larger than 0 mm, 0.43 (95% CI, 0.36-0.51) for those greater than 1 mm, 0.49 (95% CI, 0.42-0.55) for those larger than 2 mm, and 0.53 (95% CI, 0.43-0.66) for greater than 5 mm. Upon multivariate analysis, the only significant predictive variable was margin status.

For model 2, margin width turned out to be the significant variable, and only wider margins were associated with a decrease in local recurrence.

Finally, in model 3, both margin status and margin width were significantly associated with local recurrence. When modeling as negative, close, or positive margins, the lowest rates were at 2 mm (negative, 3.6%; close, 5.5%; positive, 9.5%) and 5 mm (negative, 2.9%; close, 4.1%; positive, 12.8%).

“So the initial question is the same – should we achieve a 1- to 2-mm margin for our patients as compared to a no tumor on ink, taking into account the potential for local control benefits versus morbidity and time, and cost?” said Dr. Vicini.

“The real question in my mind, is which patients with no tumor on ink require additional surgery,” he concluded. “In my opinion, it may not only be related to the margin status itself, but to the volume of disease near the margin but these meta-analyses were not designed to look at that point.”

SOURCE: Vicini et al. SABCS Abstract GS5-01

SAN ANTONIO – A margin width beyond ‘no tumor on ink’ may reduce local recurrence in certain subsets of patients undergoing breast-conserving treatment for early-stage breast cancer, according to findings from a meta-analysis.

“Further prospective studies are required to validate the appropriate margin width,” study author Frank A. Vicini, MD, of 21st Century Oncology/Michigan Healthcare Professionals in Farmington Hills, Michigan, said at the San Antonio Breast Cancer Symposium.

Dr. Vicini pointed out that the medical community has been addressing the question of “what is the appropriate margin for breast conserving therapy” for about 3 or 4 decades. A meta-analysis of 33 studies (Ann Surg Oncol. 2014 Mar;21[3]:717-30. doi: 10.1245/s10434-014-3480-5) showed that wider margins are unlikely to have a substantial benefit over “no tumor on ink.”

The results of the meta-analysis led to guidelines published by the Society of Surgical Oncology–American Society for Radiation Oncology that supported those conclusions.

“So the question now is that with additional patients and additional modeling, is this conclusion still correct?” Dr. Vicini said.

The 2014 meta-analysis had significant limitations, and to address them, Dr. Vicini and his colleagues conducted an updated analysis of all available data that included 31 of the initial studies. However, stricter criteria were used for inclusion into their review. The authors reviewed all studies published between 1995 and 2016 that had a minimum follow-up of 50 months, and that included explicit pathologic definitions of margin status and local recurrence in relation to margin status.

The final meta-analysis included 55,302 patients (74% T1 tumors; 72% node-negative disease) from a total of 38 studies, and the median follow up was 7.2 years.

The analysis used three generalized linear mixed models for the outcome of local recurrence, and random effects for study and fixed effects for various patient and study characteristics.

In model 1, all patients with at or equal margin width were compared with those who had wider margins. Model 2 examined the impact of margin width “range” as opposed to a set margin width of 0 mm to 2 mm, 2 mm to 5 mm, or greater than 5 mm. Model 3 divided margin distance by cut points of –1 mm, 2 mm, and 5 mm.

The crude rate of local recurrence was 10.3% for patients with positive margins versus 3.8% for those with negative margins that were defined as no tumor on ink or wider (P less than .001). Local recurrence rates declined as the margin distance increased: 7.2% for patients with margins 0-2 mm, 3.6% for margins of 2-5 mm, and 3.2% for margins wider than 5 mm (P less than .001 for each). The use of endocrine therapy and increasing median study year were associated with decreased rates of local recurrence in univariate models but not in multivariable analyses.

For local recurrence in model 1, a benefit for wider margins was observed, with the greatest benefit seen at 1 mm. The odds ratio (OR) for local recurrence for negative vs. close/positive margins was 0.46 (95% confidence interval, 0.4-0.53) for margins larger than 0 mm, 0.43 (95% CI, 0.36-0.51) for those greater than 1 mm, 0.49 (95% CI, 0.42-0.55) for those larger than 2 mm, and 0.53 (95% CI, 0.43-0.66) for greater than 5 mm. Upon multivariate analysis, the only significant predictive variable was margin status.

For model 2, margin width turned out to be the significant variable, and only wider margins were associated with a decrease in local recurrence.

Finally, in model 3, both margin status and margin width were significantly associated with local recurrence. When modeling as negative, close, or positive margins, the lowest rates were at 2 mm (negative, 3.6%; close, 5.5%; positive, 9.5%) and 5 mm (negative, 2.9%; close, 4.1%; positive, 12.8%).

“So the initial question is the same – should we achieve a 1- to 2-mm margin for our patients as compared to a no tumor on ink, taking into account the potential for local control benefits versus morbidity and time, and cost?” said Dr. Vicini.

“The real question in my mind, is which patients with no tumor on ink require additional surgery,” he concluded. “In my opinion, it may not only be related to the margin status itself, but to the volume of disease near the margin but these meta-analyses were not designed to look at that point.”

SOURCE: Vicini et al. SABCS Abstract GS5-01

SAN ANTONIO – A margin width beyond ‘no tumor on ink’ may reduce local recurrence in certain subsets of patients undergoing breast-conserving treatment for early-stage breast cancer, according to findings from a meta-analysis.

“Further prospective studies are required to validate the appropriate margin width,” study author Frank A. Vicini, MD, of 21st Century Oncology/Michigan Healthcare Professionals in Farmington Hills, Michigan, said at the San Antonio Breast Cancer Symposium.

Dr. Vicini pointed out that the medical community has been addressing the question of “what is the appropriate margin for breast conserving therapy” for about 3 or 4 decades. A meta-analysis of 33 studies (Ann Surg Oncol. 2014 Mar;21[3]:717-30. doi: 10.1245/s10434-014-3480-5) showed that wider margins are unlikely to have a substantial benefit over “no tumor on ink.”

The results of the meta-analysis led to guidelines published by the Society of Surgical Oncology–American Society for Radiation Oncology that supported those conclusions.

“So the question now is that with additional patients and additional modeling, is this conclusion still correct?” Dr. Vicini said.

The 2014 meta-analysis had significant limitations, and to address them, Dr. Vicini and his colleagues conducted an updated analysis of all available data that included 31 of the initial studies. However, stricter criteria were used for inclusion into their review. The authors reviewed all studies published between 1995 and 2016 that had a minimum follow-up of 50 months, and that included explicit pathologic definitions of margin status and local recurrence in relation to margin status.

The final meta-analysis included 55,302 patients (74% T1 tumors; 72% node-negative disease) from a total of 38 studies, and the median follow up was 7.2 years.

The analysis used three generalized linear mixed models for the outcome of local recurrence, and random effects for study and fixed effects for various patient and study characteristics.

In model 1, all patients with at or equal margin width were compared with those who had wider margins. Model 2 examined the impact of margin width “range” as opposed to a set margin width of 0 mm to 2 mm, 2 mm to 5 mm, or greater than 5 mm. Model 3 divided margin distance by cut points of –1 mm, 2 mm, and 5 mm.

The crude rate of local recurrence was 10.3% for patients with positive margins versus 3.8% for those with negative margins that were defined as no tumor on ink or wider (P less than .001). Local recurrence rates declined as the margin distance increased: 7.2% for patients with margins 0-2 mm, 3.6% for margins of 2-5 mm, and 3.2% for margins wider than 5 mm (P less than .001 for each). The use of endocrine therapy and increasing median study year were associated with decreased rates of local recurrence in univariate models but not in multivariable analyses.

For local recurrence in model 1, a benefit for wider margins was observed, with the greatest benefit seen at 1 mm. The odds ratio (OR) for local recurrence for negative vs. close/positive margins was 0.46 (95% confidence interval, 0.4-0.53) for margins larger than 0 mm, 0.43 (95% CI, 0.36-0.51) for those greater than 1 mm, 0.49 (95% CI, 0.42-0.55) for those larger than 2 mm, and 0.53 (95% CI, 0.43-0.66) for greater than 5 mm. Upon multivariate analysis, the only significant predictive variable was margin status.

For model 2, margin width turned out to be the significant variable, and only wider margins were associated with a decrease in local recurrence.

Finally, in model 3, both margin status and margin width were significantly associated with local recurrence. When modeling as negative, close, or positive margins, the lowest rates were at 2 mm (negative, 3.6%; close, 5.5%; positive, 9.5%) and 5 mm (negative, 2.9%; close, 4.1%; positive, 12.8%).

“So the initial question is the same – should we achieve a 1- to 2-mm margin for our patients as compared to a no tumor on ink, taking into account the potential for local control benefits versus morbidity and time, and cost?” said Dr. Vicini.

“The real question in my mind, is which patients with no tumor on ink require additional surgery,” he concluded. “In my opinion, it may not only be related to the margin status itself, but to the volume of disease near the margin but these meta-analyses were not designed to look at that point.”

SOURCE: Vicini et al. SABCS Abstract GS5-01

SAN ANTONIO – Enzalutamide added to exemestane improved progression-free survival (PFS) in patients with hormone receptor (HR)-positive advanced breast cancer, investigators reported.

Specifically, it improved outcomes in patients who had not received any prior endocrine therapy and who were positive for a gene signature-based biomarker indicating androgen receptor (AR) signaling.

Patients in this subset who were treated with combination enzalutamide and exemestane achieved a median PFS of 16.5 months, which was significantly higher than the 4 months observed with placebo and exemestane.

However, the addition of enzalutamide had no effect on PFS in the overall cohort or among patients who were biomarker positive but who had received prior endocrine therapy.

“The study met its primary endpoint in improving PFS in the enzalutamide plus exemestane-treated patients who were biomarker positive and HR positive with no prior endocrine therapy for advanced disease as compared [with] exemestane alone,” Denise A. Yardley, MD, of Tennessee Oncology, Nashville, said at the San Antonio Breast Cancer Symposium.

“The role of the AR in HR-positive breast cancer and the predictive value of the identified biomarker are still unclear and will require further studies and validation,” said Dr. Yardley.

SOURCE: Yardley et al. SABCS Abstract GS4-07

SAN ANTONIO – Enzalutamide added to exemestane improved progression-free survival (PFS) in patients with hormone receptor (HR)-positive advanced breast cancer, investigators reported.

Specifically, it improved outcomes in patients who had not received any prior endocrine therapy and who were positive for a gene signature-based biomarker indicating androgen receptor (AR) signaling.

Patients in this subset who were treated with combination enzalutamide and exemestane achieved a median PFS of 16.5 months, which was significantly higher than the 4 months observed with placebo and exemestane.

However, the addition of enzalutamide had no effect on PFS in the overall cohort or among patients who were biomarker positive but who had received prior endocrine therapy.

“The study met its primary endpoint in improving PFS in the enzalutamide plus exemestane-treated patients who were biomarker positive and HR positive with no prior endocrine therapy for advanced disease as compared [with] exemestane alone,” Denise A. Yardley, MD, of Tennessee Oncology, Nashville, said at the San Antonio Breast Cancer Symposium.

“The role of the AR in HR-positive breast cancer and the predictive value of the identified biomarker are still unclear and will require further studies and validation,” said Dr. Yardley.

SOURCE: Yardley et al. SABCS Abstract GS4-07

SAN ANTONIO – Enzalutamide added to exemestane improved progression-free survival (PFS) in patients with hormone receptor (HR)-positive advanced breast cancer, investigators reported.

Specifically, it improved outcomes in patients who had not received any prior endocrine therapy and who were positive for a gene signature-based biomarker indicating androgen receptor (AR) signaling.

Patients in this subset who were treated with combination enzalutamide and exemestane achieved a median PFS of 16.5 months, which was significantly higher than the 4 months observed with placebo and exemestane.

However, the addition of enzalutamide had no effect on PFS in the overall cohort or among patients who were biomarker positive but who had received prior endocrine therapy.

“The study met its primary endpoint in improving PFS in the enzalutamide plus exemestane-treated patients who were biomarker positive and HR positive with no prior endocrine therapy for advanced disease as compared [with] exemestane alone,” Denise A. Yardley, MD, of Tennessee Oncology, Nashville, said at the San Antonio Breast Cancer Symposium.

“The role of the AR in HR-positive breast cancer and the predictive value of the identified biomarker are still unclear and will require further studies and validation,” said Dr. Yardley.

SOURCE: Yardley et al. SABCS Abstract GS4-07

SAN ANTONIO – Dual HER2 targeting with lapatinib added to 16 weeks of trastuzumab significantly improved event-free survival (EFS), compared with trastuzumab alone, among women with HER2-positive breast cancer.

EFS was significantly longer in the combination arm versus single-blockade therapy (hazard ratio, 0.35; 95% confidence interval, 0.15-0.84; P = .013).

“Overall survival was also increased, but the number of events was very small,” said study author Ian E. Krop, MD, of the Dana-Farber Cancer Institute in Boston, who presented the study results at the San Antonio Breast Cancer Symposium.

As expected, and consistent with other studies, the pathologic complete response (pCR) rate with dual blockade was associated with favorable long-term outcomes, and the effect was most pronounced in HR- and HER2 enriched cancers.

However, Dr. Krop cautioned that these results need to be seen in the context of two larger trials that failed to find a benefit for dual-blockade HER2 therapy in either the adjuvant or neoadjuvant setting.

Previous research has shown that trastuzumab and lapatinib are synergistic, potently inhibiting HER2 signaling in preclinical trials. The combination of both agents is also active in both untreated and heavily pretreated HER2+ advanced breast cancer. The addition of lapatinib to trastuzumab plus chemotherapy has also been associated with a pCR rate that was statistically significant in many studies.

But despite this “wealth of evidence,” the largest of these studies, the phase 3 ALTTO study, failed to show a benefit for dual HER2 blockade. The same was true for the neoadjuvant Neo ALTTO study. Both studies failed to show an improvement in EFS or overall survival.

The current trial, CALGB 40601, a randomized phase 3 trial, assessed the effect of dual HER2 blockade consisting of trastuzumab and lapatinib added to paclitaxel on rates of pCR, and the researchers also looked at tumor and microenvironment molecular features. Dr. Krop noted that they had previously found that rates of pCR were numerically but not significantly increased with combination-blockade therapy; they had also found that the tumor molecular subtype and evidence of immune activation were independent factors affecting rates of pCR.

Dr. Krop presented results from a secondary analysis in which they evaluated the effects of treatment arm and gene expression–defined subgroups on EFS.

A total of 305 patients with stage II and III HER2+ breast cancer were randomized to receive 16 weeks of either paclitaxel plus trastuzumab alone or that combination with lapatinib as well before undergoing surgery. Evaluable information regarding EFS and RNA-sequencing gene expression was available for 265 patients.

“Despite the lack of significant benefits in other studies, we did demonstrate an improvement in EFS,” said Dr. Krop, noting that it was more pronounced in the subset of HR- patients (HR, 0.12; P = .0160).

EFS was also significantly longer among those who achieved pCR than those who didn’t (HR, 0.34; P = .0032).

In an exploratory analysis, Dr. Krop and his colleagues assessed whether there was a difference in rates of pCR by subtype, and they found that luminal A and luminal B did not have much of an effect on rates of pCR. However, patients with HER2-enriched disease who had a pCR had significantly better EFS than those who did not (HR, 0.14; 95% CI, 0.04-0.44; P less than .0001).

Conversely, patients with HER2-enriched disease who did not achieve pCR had a substantial risk of recurrence.

When looking at EFS by intrinsic subtype, the addition of lapatinib had the most effect on luminal A cancers. “This shows that there was some discordance between analyses by pCR and by long-term endpoint,” Dr. Krop said.

Finally, among gene expression signatures, only immune activation measured by an immunoglobulin G signature was associated with an improvement in EFS (HR, 0.70; 95% CI, 0.50-0.98; P = .04).

“These data are hypothesis generating and require validation,” Dr. Krop concluded. He added that a combined analysis of this trial, along with the Neo ALTTO and others, is planned.

SOURCE: Krop IE et al. SABCS 2017 Abstract GS3-02.

SAN ANTONIO – Dual HER2 targeting with lapatinib added to 16 weeks of trastuzumab significantly improved event-free survival (EFS), compared with trastuzumab alone, among women with HER2-positive breast cancer.

EFS was significantly longer in the combination arm versus single-blockade therapy (hazard ratio, 0.35; 95% confidence interval, 0.15-0.84; P = .013).

“Overall survival was also increased, but the number of events was very small,” said study author Ian E. Krop, MD, of the Dana-Farber Cancer Institute in Boston, who presented the study results at the San Antonio Breast Cancer Symposium.

As expected, and consistent with other studies, the pathologic complete response (pCR) rate with dual blockade was associated with favorable long-term outcomes, and the effect was most pronounced in HR- and HER2 enriched cancers.

However, Dr. Krop cautioned that these results need to be seen in the context of two larger trials that failed to find a benefit for dual-blockade HER2 therapy in either the adjuvant or neoadjuvant setting.

Previous research has shown that trastuzumab and lapatinib are synergistic, potently inhibiting HER2 signaling in preclinical trials. The combination of both agents is also active in both untreated and heavily pretreated HER2+ advanced breast cancer. The addition of lapatinib to trastuzumab plus chemotherapy has also been associated with a pCR rate that was statistically significant in many studies.

But despite this “wealth of evidence,” the largest of these studies, the phase 3 ALTTO study, failed to show a benefit for dual HER2 blockade. The same was true for the neoadjuvant Neo ALTTO study. Both studies failed to show an improvement in EFS or overall survival.

The current trial, CALGB 40601, a randomized phase 3 trial, assessed the effect of dual HER2 blockade consisting of trastuzumab and lapatinib added to paclitaxel on rates of pCR, and the researchers also looked at tumor and microenvironment molecular features. Dr. Krop noted that they had previously found that rates of pCR were numerically but not significantly increased with combination-blockade therapy; they had also found that the tumor molecular subtype and evidence of immune activation were independent factors affecting rates of pCR.

Dr. Krop presented results from a secondary analysis in which they evaluated the effects of treatment arm and gene expression–defined subgroups on EFS.

A total of 305 patients with stage II and III HER2+ breast cancer were randomized to receive 16 weeks of either paclitaxel plus trastuzumab alone or that combination with lapatinib as well before undergoing surgery. Evaluable information regarding EFS and RNA-sequencing gene expression was available for 265 patients.

“Despite the lack of significant benefits in other studies, we did demonstrate an improvement in EFS,” said Dr. Krop, noting that it was more pronounced in the subset of HR- patients (HR, 0.12; P = .0160).

EFS was also significantly longer among those who achieved pCR than those who didn’t (HR, 0.34; P = .0032).

In an exploratory analysis, Dr. Krop and his colleagues assessed whether there was a difference in rates of pCR by subtype, and they found that luminal A and luminal B did not have much of an effect on rates of pCR. However, patients with HER2-enriched disease who had a pCR had significantly better EFS than those who did not (HR, 0.14; 95% CI, 0.04-0.44; P less than .0001).

Conversely, patients with HER2-enriched disease who did not achieve pCR had a substantial risk of recurrence.

When looking at EFS by intrinsic subtype, the addition of lapatinib had the most effect on luminal A cancers. “This shows that there was some discordance between analyses by pCR and by long-term endpoint,” Dr. Krop said.

Finally, among gene expression signatures, only immune activation measured by an immunoglobulin G signature was associated with an improvement in EFS (HR, 0.70; 95% CI, 0.50-0.98; P = .04).

“These data are hypothesis generating and require validation,” Dr. Krop concluded. He added that a combined analysis of this trial, along with the Neo ALTTO and others, is planned.

SOURCE: Krop IE et al. SABCS 2017 Abstract GS3-02.

SAN ANTONIO – Dual HER2 targeting with lapatinib added to 16 weeks of trastuzumab significantly improved event-free survival (EFS), compared with trastuzumab alone, among women with HER2-positive breast cancer.

EFS was significantly longer in the combination arm versus single-blockade therapy (hazard ratio, 0.35; 95% confidence interval, 0.15-0.84; P = .013).

“Overall survival was also increased, but the number of events was very small,” said study author Ian E. Krop, MD, of the Dana-Farber Cancer Institute in Boston, who presented the study results at the San Antonio Breast Cancer Symposium.

As expected, and consistent with other studies, the pathologic complete response (pCR) rate with dual blockade was associated with favorable long-term outcomes, and the effect was most pronounced in HR- and HER2 enriched cancers.

However, Dr. Krop cautioned that these results need to be seen in the context of two larger trials that failed to find a benefit for dual-blockade HER2 therapy in either the adjuvant or neoadjuvant setting.

Previous research has shown that trastuzumab and lapatinib are synergistic, potently inhibiting HER2 signaling in preclinical trials. The combination of both agents is also active in both untreated and heavily pretreated HER2+ advanced breast cancer. The addition of lapatinib to trastuzumab plus chemotherapy has also been associated with a pCR rate that was statistically significant in many studies.

But despite this “wealth of evidence,” the largest of these studies, the phase 3 ALTTO study, failed to show a benefit for dual HER2 blockade. The same was true for the neoadjuvant Neo ALTTO study. Both studies failed to show an improvement in EFS or overall survival.

The current trial, CALGB 40601, a randomized phase 3 trial, assessed the effect of dual HER2 blockade consisting of trastuzumab and lapatinib added to paclitaxel on rates of pCR, and the researchers also looked at tumor and microenvironment molecular features. Dr. Krop noted that they had previously found that rates of pCR were numerically but not significantly increased with combination-blockade therapy; they had also found that the tumor molecular subtype and evidence of immune activation were independent factors affecting rates of pCR.

Dr. Krop presented results from a secondary analysis in which they evaluated the effects of treatment arm and gene expression–defined subgroups on EFS.

A total of 305 patients with stage II and III HER2+ breast cancer were randomized to receive 16 weeks of either paclitaxel plus trastuzumab alone or that combination with lapatinib as well before undergoing surgery. Evaluable information regarding EFS and RNA-sequencing gene expression was available for 265 patients.

“Despite the lack of significant benefits in other studies, we did demonstrate an improvement in EFS,” said Dr. Krop, noting that it was more pronounced in the subset of HR- patients (HR, 0.12; P = .0160).

EFS was also significantly longer among those who achieved pCR than those who didn’t (HR, 0.34; P = .0032).

In an exploratory analysis, Dr. Krop and his colleagues assessed whether there was a difference in rates of pCR by subtype, and they found that luminal A and luminal B did not have much of an effect on rates of pCR. However, patients with HER2-enriched disease who had a pCR had significantly better EFS than those who did not (HR, 0.14; 95% CI, 0.04-0.44; P less than .0001).

Conversely, patients with HER2-enriched disease who did not achieve pCR had a substantial risk of recurrence.

When looking at EFS by intrinsic subtype, the addition of lapatinib had the most effect on luminal A cancers. “This shows that there was some discordance between analyses by pCR and by long-term endpoint,” Dr. Krop said.

Finally, among gene expression signatures, only immune activation measured by an immunoglobulin G signature was associated with an improvement in EFS (HR, 0.70; 95% CI, 0.50-0.98; P = .04).

“These data are hypothesis generating and require validation,” Dr. Krop concluded. He added that a combined analysis of this trial, along with the Neo ALTTO and others, is planned.

SOURCE: Krop IE et al. SABCS 2017 Abstract GS3-02.

SAN ANTONIO – Axillary dissection can be avoided in patients with early breast cancer and limited sentinel node involvement, investigators reported at the San Antonio Breast Cancer Symposium.

Both disease-free survival (DFS) and overall survival (OS) were similar in a population of patients with cT1-T2 N0M0 breast cancer and sentinel node micrometastases who underwent axillary dissection (AD), compared with those who did not. Complications associated with axillary surgery can be avoided in this population, without any adverse effect on survival.

“Our findings are fully consistent with those of the Z0011 trial, which after 10 years found no differences between the AD and no-AD groups for any endpoint in patients with moderate disease burden in the axilla undergoing conservative breast surgery,” said study author Viviana Galimberti, MD, of the European Institute of Oncology in Milan.

In the ACOSOG Z0011, trial, the use of sentinel node biopsy alone was not inferior to AD in patients with limited sentinel node metastasis treated with breast conservation and systemic therapy.

“We also suggest that non-AD is acceptable treatment in patients scheduled for mastectomy,” Dr. Galimberti said.

For patients with breast cancer and metastases in the sentinel nodes, AD has been the standard of care, but for those with limited sentinel node involvement, it was hypothesized that AD might not be necessary.

The phase 3 IBCSG 23-01 study was a multicenter, randomized, noninferiority trial that compared DFS in breast cancer patients with one or more micrometastases (greater than or equal to 2 mm) in the sentinel nodes who were randomized to either AD or no axillary dissection (no-AD). The 5-year results, which were published in 2013 in the Lancet Oncology (2013 Jun;14[7]:e251-2) showed no difference in DFS between the two groups.

At the meeting, Dr. Galimberti reported on outcomes after an extended median follow-up of 9.8 years. A cohort of 934 women (931 evaluable) were enrolled from 27 centers from 2001 to 2010 and randomized to either AD or no AD (467 in the no-AD group and 464 in the AD group).

The results were similar to those reported at 5 years. The 10-year DFS rates were similar for both cohorts; 77% for non-AD vs. 75% for AD (hazard ratio [no-AD vs. AD], 0.85; 95% confidence interval, 0.65-1.11; log-rank P = .23; noninferiority P = .002).

The rate of axillary failure in the no-AD group was low, Dr. Galimberti pointed out, at 1.7% and 0.8% among women who underwent breast-conserving surgery. There were nine ipsilateral axillary events in the no-AD group vs. three in the AD group, and 45 deaths in the no-AD group vs. 58 in the AD group. The 10-year OS was 91% (95% CI, 88%-94%) in the no-AD group and 88% (95% CI, 85%-92%) in the AD group (HR [no-AD vs. AD], 0.77; 95% CI, 0.56-1.07; log-rank P = .19).

There was no difference between groups for the main endpoint of DFS or the secondary endpoint of OS, said Dr. Galimberti.

In subgroup analyses, which included tumor size, estrogen-receptor status, progesterone-receptor status, tumor grade, and type of surgery, there were no subgroups identified that benefited from AD over no-AD.

“Our data fully support the change in clinical practice that started after the early published results,” Dr Galimberti concluded. “No AD is now standard treatment in early breast cancer when the sentinel node is only minimally involved.”

The study received no outside funding and the authors had no disclosures.

SOURCE: Galimberti et al. SABCS Abstract GS5-02

SAN ANTONIO – Axillary dissection can be avoided in patients with early breast cancer and limited sentinel node involvement, investigators reported at the San Antonio Breast Cancer Symposium.

Both disease-free survival (DFS) and overall survival (OS) were similar in a population of patients with cT1-T2 N0M0 breast cancer and sentinel node micrometastases who underwent axillary dissection (AD), compared with those who did not. Complications associated with axillary surgery can be avoided in this population, without any adverse effect on survival.

“Our findings are fully consistent with those of the Z0011 trial, which after 10 years found no differences between the AD and no-AD groups for any endpoint in patients with moderate disease burden in the axilla undergoing conservative breast surgery,” said study author Viviana Galimberti, MD, of the European Institute of Oncology in Milan.

In the ACOSOG Z0011, trial, the use of sentinel node biopsy alone was not inferior to AD in patients with limited sentinel node metastasis treated with breast conservation and systemic therapy.

“We also suggest that non-AD is acceptable treatment in patients scheduled for mastectomy,” Dr. Galimberti said.

For patients with breast cancer and metastases in the sentinel nodes, AD has been the standard of care, but for those with limited sentinel node involvement, it was hypothesized that AD might not be necessary.

The phase 3 IBCSG 23-01 study was a multicenter, randomized, noninferiority trial that compared DFS in breast cancer patients with one or more micrometastases (greater than or equal to 2 mm) in the sentinel nodes who were randomized to either AD or no axillary dissection (no-AD). The 5-year results, which were published in 2013 in the Lancet Oncology (2013 Jun;14[7]:e251-2) showed no difference in DFS between the two groups.

At the meeting, Dr. Galimberti reported on outcomes after an extended median follow-up of 9.8 years. A cohort of 934 women (931 evaluable) were enrolled from 27 centers from 2001 to 2010 and randomized to either AD or no AD (467 in the no-AD group and 464 in the AD group).

The results were similar to those reported at 5 years. The 10-year DFS rates were similar for both cohorts; 77% for non-AD vs. 75% for AD (hazard ratio [no-AD vs. AD], 0.85; 95% confidence interval, 0.65-1.11; log-rank P = .23; noninferiority P = .002).

The rate of axillary failure in the no-AD group was low, Dr. Galimberti pointed out, at 1.7% and 0.8% among women who underwent breast-conserving surgery. There were nine ipsilateral axillary events in the no-AD group vs. three in the AD group, and 45 deaths in the no-AD group vs. 58 in the AD group. The 10-year OS was 91% (95% CI, 88%-94%) in the no-AD group and 88% (95% CI, 85%-92%) in the AD group (HR [no-AD vs. AD], 0.77; 95% CI, 0.56-1.07; log-rank P = .19).

There was no difference between groups for the main endpoint of DFS or the secondary endpoint of OS, said Dr. Galimberti.

In subgroup analyses, which included tumor size, estrogen-receptor status, progesterone-receptor status, tumor grade, and type of surgery, there were no subgroups identified that benefited from AD over no-AD.

“Our data fully support the change in clinical practice that started after the early published results,” Dr Galimberti concluded. “No AD is now standard treatment in early breast cancer when the sentinel node is only minimally involved.”

The study received no outside funding and the authors had no disclosures.

SOURCE: Galimberti et al. SABCS Abstract GS5-02

SAN ANTONIO – Axillary dissection can be avoided in patients with early breast cancer and limited sentinel node involvement, investigators reported at the San Antonio Breast Cancer Symposium.

Both disease-free survival (DFS) and overall survival (OS) were similar in a population of patients with cT1-T2 N0M0 breast cancer and sentinel node micrometastases who underwent axillary dissection (AD), compared with those who did not. Complications associated with axillary surgery can be avoided in this population, without any adverse effect on survival.

“Our findings are fully consistent with those of the Z0011 trial, which after 10 years found no differences between the AD and no-AD groups for any endpoint in patients with moderate disease burden in the axilla undergoing conservative breast surgery,” said study author Viviana Galimberti, MD, of the European Institute of Oncology in Milan.

In the ACOSOG Z0011, trial, the use of sentinel node biopsy alone was not inferior to AD in patients with limited sentinel node metastasis treated with breast conservation and systemic therapy.

“We also suggest that non-AD is acceptable treatment in patients scheduled for mastectomy,” Dr. Galimberti said.

For patients with breast cancer and metastases in the sentinel nodes, AD has been the standard of care, but for those with limited sentinel node involvement, it was hypothesized that AD might not be necessary.

The phase 3 IBCSG 23-01 study was a multicenter, randomized, noninferiority trial that compared DFS in breast cancer patients with one or more micrometastases (greater than or equal to 2 mm) in the sentinel nodes who were randomized to either AD or no axillary dissection (no-AD). The 5-year results, which were published in 2013 in the Lancet Oncology (2013 Jun;14[7]:e251-2) showed no difference in DFS between the two groups.

At the meeting, Dr. Galimberti reported on outcomes after an extended median follow-up of 9.8 years. A cohort of 934 women (931 evaluable) were enrolled from 27 centers from 2001 to 2010 and randomized to either AD or no AD (467 in the no-AD group and 464 in the AD group).

The results were similar to those reported at 5 years. The 10-year DFS rates were similar for both cohorts; 77% for non-AD vs. 75% for AD (hazard ratio [no-AD vs. AD], 0.85; 95% confidence interval, 0.65-1.11; log-rank P = .23; noninferiority P = .002).

The rate of axillary failure in the no-AD group was low, Dr. Galimberti pointed out, at 1.7% and 0.8% among women who underwent breast-conserving surgery. There were nine ipsilateral axillary events in the no-AD group vs. three in the AD group, and 45 deaths in the no-AD group vs. 58 in the AD group. The 10-year OS was 91% (95% CI, 88%-94%) in the no-AD group and 88% (95% CI, 85%-92%) in the AD group (HR [no-AD vs. AD], 0.77; 95% CI, 0.56-1.07; log-rank P = .19).

There was no difference between groups for the main endpoint of DFS or the secondary endpoint of OS, said Dr. Galimberti.

In subgroup analyses, which included tumor size, estrogen-receptor status, progesterone-receptor status, tumor grade, and type of surgery, there were no subgroups identified that benefited from AD over no-AD.

“Our data fully support the change in clinical practice that started after the early published results,” Dr Galimberti concluded. “No AD is now standard treatment in early breast cancer when the sentinel node is only minimally involved.”

The study received no outside funding and the authors had no disclosures.

SOURCE: Galimberti et al. SABCS Abstract GS5-02

SAN ANTONIO – Among patients receiving trastuzumab plus lapatinib neoadjuvant therapy for HER2-positive early breast cancer, amplification of ERBB2 was predictive of a pathologic complete response (pCR), according to findings presented at the San Antonio Breast Cancer Symposium.

However, ERBB2 mRNA expression and PAM50-enriched HER2 better predicted pCR, said lead study author Cristos Sotiriou, MD, of the Breast Cancer Translational Research Laboratory at the Institut Jules Bordet in Belgium

High genomic instability was associated with a higher pCR rate in patients with estrogen receptor–positive tumors, but copy number alterations (CNAs) were not associated with event-free survival (EFS).

In the large phase 3 NeoALTTO trial, lapatinib combined with trastuzumab in the neoadjuvant setting nearly doubled the pCR rate as compared with either agent used alone. The 3-year EFS was also improved with dual HER2 blockage versus single HER2 therapy (84% for the combination, hazard ratio, 0.78; P = .33 vs. 78% for lapatinib alone and 76% for trastuzumab alone, HR, 1.06; P = .81 for both).

The researchers of this trial also found that pCR was a surrogate for long-term outcome.

“Expression of ERBB2, ESR1, and immune signatures were the main drivers of pCR,” said Dr. Sotiriou.

The main goal of the current study was to investigate the relevance of CNAs for pCR and EFS in this population. A total of 455 patients were enrolled in the NeoALTTO study, and of this cohort, 270 had tumor content that was sufficient to assay for CNAs. Tumor-infiltrating lymphocytes and gene expression were also obtained and the genome instability index was calculated, and 184 samples were included in the final analysis.

Of the cancer genes, only ERBB2 was predictive of pCR.

A total of 159 recurrent CNA regions were identified. ERBB2 amplification was associated with high pCR (P = .0007), but less than ERBB2 expression, and it lost its significance after correcting for ERBB2 expression.

The genome instability index (GII) was defined as the “median absolute deviation of the normalized copy number” and independent of ERBB2 amplification, the pCR rate increased with the GII (P = .03.

Amplification of two regions on 6q23-24 was significantly associated with higher pCR (P = .00005 and P = .00087). One of the segments harbored 39 genes, some with an expression level that was also predictive of pCR. The 6q23-24 segment was associated with pCR in estrogen receptor–positive tumors only (interaction test P = .04).

After multiple testing correction, there were no amplified regions or genes found to be predictive of EFS.

“A novel amplified region on 6q23-24 was shown to be predictive of pCR, in particular for estrogen receptor–positive tumors,” said Dr. Sotiriou. “This may warrant further investigation.”

SOURCE: Sotiriou et al. SABCS Abstract GS1-04

SAN ANTONIO – Among patients receiving trastuzumab plus lapatinib neoadjuvant therapy for HER2-positive early breast cancer, amplification of ERBB2 was predictive of a pathologic complete response (pCR), according to findings presented at the San Antonio Breast Cancer Symposium.

However, ERBB2 mRNA expression and PAM50-enriched HER2 better predicted pCR, said lead study author Cristos Sotiriou, MD, of the Breast Cancer Translational Research Laboratory at the Institut Jules Bordet in Belgium

High genomic instability was associated with a higher pCR rate in patients with estrogen receptor–positive tumors, but copy number alterations (CNAs) were not associated with event-free survival (EFS).

In the large phase 3 NeoALTTO trial, lapatinib combined with trastuzumab in the neoadjuvant setting nearly doubled the pCR rate as compared with either agent used alone. The 3-year EFS was also improved with dual HER2 blockage versus single HER2 therapy (84% for the combination, hazard ratio, 0.78; P = .33 vs. 78% for lapatinib alone and 76% for trastuzumab alone, HR, 1.06; P = .81 for both).

The researchers of this trial also found that pCR was a surrogate for long-term outcome.

“Expression of ERBB2, ESR1, and immune signatures were the main drivers of pCR,” said Dr. Sotiriou.

The main goal of the current study was to investigate the relevance of CNAs for pCR and EFS in this population. A total of 455 patients were enrolled in the NeoALTTO study, and of this cohort, 270 had tumor content that was sufficient to assay for CNAs. Tumor-infiltrating lymphocytes and gene expression were also obtained and the genome instability index was calculated, and 184 samples were included in the final analysis.

Of the cancer genes, only ERBB2 was predictive of pCR.

A total of 159 recurrent CNA regions were identified. ERBB2 amplification was associated with high pCR (P = .0007), but less than ERBB2 expression, and it lost its significance after correcting for ERBB2 expression.

The genome instability index (GII) was defined as the “median absolute deviation of the normalized copy number” and independent of ERBB2 amplification, the pCR rate increased with the GII (P = .03.

Amplification of two regions on 6q23-24 was significantly associated with higher pCR (P = .00005 and P = .00087). One of the segments harbored 39 genes, some with an expression level that was also predictive of pCR. The 6q23-24 segment was associated with pCR in estrogen receptor–positive tumors only (interaction test P = .04).

After multiple testing correction, there were no amplified regions or genes found to be predictive of EFS.

“A novel amplified region on 6q23-24 was shown to be predictive of pCR, in particular for estrogen receptor–positive tumors,” said Dr. Sotiriou. “This may warrant further investigation.”

SOURCE: Sotiriou et al. SABCS Abstract GS1-04

SAN ANTONIO – Among patients receiving trastuzumab plus lapatinib neoadjuvant therapy for HER2-positive early breast cancer, amplification of ERBB2 was predictive of a pathologic complete response (pCR), according to findings presented at the San Antonio Breast Cancer Symposium.

However, ERBB2 mRNA expression and PAM50-enriched HER2 better predicted pCR, said lead study author Cristos Sotiriou, MD, of the Breast Cancer Translational Research Laboratory at the Institut Jules Bordet in Belgium

High genomic instability was associated with a higher pCR rate in patients with estrogen receptor–positive tumors, but copy number alterations (CNAs) were not associated with event-free survival (EFS).

In the large phase 3 NeoALTTO trial, lapatinib combined with trastuzumab in the neoadjuvant setting nearly doubled the pCR rate as compared with either agent used alone. The 3-year EFS was also improved with dual HER2 blockage versus single HER2 therapy (84% for the combination, hazard ratio, 0.78; P = .33 vs. 78% for lapatinib alone and 76% for trastuzumab alone, HR, 1.06; P = .81 for both).

The researchers of this trial also found that pCR was a surrogate for long-term outcome.

“Expression of ERBB2, ESR1, and immune signatures were the main drivers of pCR,” said Dr. Sotiriou.

The main goal of the current study was to investigate the relevance of CNAs for pCR and EFS in this population. A total of 455 patients were enrolled in the NeoALTTO study, and of this cohort, 270 had tumor content that was sufficient to assay for CNAs. Tumor-infiltrating lymphocytes and gene expression were also obtained and the genome instability index was calculated, and 184 samples were included in the final analysis.

Of the cancer genes, only ERBB2 was predictive of pCR.

A total of 159 recurrent CNA regions were identified. ERBB2 amplification was associated with high pCR (P = .0007), but less than ERBB2 expression, and it lost its significance after correcting for ERBB2 expression.

The genome instability index (GII) was defined as the “median absolute deviation of the normalized copy number” and independent of ERBB2 amplification, the pCR rate increased with the GII (P = .03.

Amplification of two regions on 6q23-24 was significantly associated with higher pCR (P = .00005 and P = .00087). One of the segments harbored 39 genes, some with an expression level that was also predictive of pCR. The 6q23-24 segment was associated with pCR in estrogen receptor–positive tumors only (interaction test P = .04).

After multiple testing correction, there were no amplified regions or genes found to be predictive of EFS.

“A novel amplified region on 6q23-24 was shown to be predictive of pCR, in particular for estrogen receptor–positive tumors,” said Dr. Sotiriou. “This may warrant further investigation.”

SOURCE: Sotiriou et al. SABCS Abstract GS1-04

SAN ANTONIO – A biological risk signature can help guide decisions about use of adjuvant radiation therapy in patients with ductal carcinoma in situ (DCIS), suggests a validation study reported at the San Antonio Breast Cancer Symposium.

Radiation therapy reduces the 10-year risk of any ipsilateral recurrence in this population by about 50% as established in a large overview of trials (J Natl Cancer Inst Monogr. 2010;2010:162-77), noted lead investigator Fredrik Wärnberg, MD, PhD, of Uppsala Academic Hospital, Uppsala University, Sweden. But factors such as tumor size, grade, and margins have not been helpful in identifying patients most likely to benefit.

Study details

Main results from the SweDCIS trial, previously reported (J Clin Oncol. 2014;32:3613-8), showed that adjuvant radiation therapy reduced recurrences, yielding a 12% absolute reduction in risk of ipsilateral recurrence (10% for in situ recurrences and 2% for invasive recurrences).

For the validation study, Dr. Wärnberg and his colleagues were able to obtain tissue and biological signature results, blinded to patient outcome, for 56% of the original trial population. About half of patients each were determined to have low risk scores and elevated risk scores.

Among the 506 patients with clear margins, the score, analyzed as a continuous variable, was associated with risk of any (in situ or invasive) ipsilateral recurrence during follow-up (hazard ratio, 1.49 per 5-unit increase; P = .038).

In a multivariate model, receipt of radiation therapy was associated with a 52% relative reduction in 10-year risk of any ipsilateral recurrence for those with a low-risk score (HR, 0.48; P = .04) and a greater 69% relative reduction for those with an elevated risk score (HR, 0.31; P less than .001).

Radiation therapy did not significantly reduce the risk of ipsilateral invasive recurrence in the low risk group (HR, 0.84; P = .70), but it did in the elevated risk group (HR, 0.24; P = .012).

These findings essentially mirrored those of a 2015 validation study in a separate cohort of 526 patients from Uppsala University Hospital and the University of Massachusetts, according to Dr. Wärnberg. “We found highly consistent data with these two different sets,” he said.

Analyses additionally showed that radiation therapy reduced the 10-year risk of an invasive breast cancer recurrence by an absolute 1% for patients with low risk scores (not significant) but by an absolute 9% for patients with elevated risk scores (P = .012).

Dr. Wärnberg disclosed that he had no relevant conflicts of interest. The study was funded in part by PreludeDx.

SOURCE: Warnberg et al., SABCS Abstract GS5-08

SAN ANTONIO – A biological risk signature can help guide decisions about use of adjuvant radiation therapy in patients with ductal carcinoma in situ (DCIS), suggests a validation study reported at the San Antonio Breast Cancer Symposium.

Radiation therapy reduces the 10-year risk of any ipsilateral recurrence in this population by about 50% as established in a large overview of trials (J Natl Cancer Inst Monogr. 2010;2010:162-77), noted lead investigator Fredrik Wärnberg, MD, PhD, of Uppsala Academic Hospital, Uppsala University, Sweden. But factors such as tumor size, grade, and margins have not been helpful in identifying patients most likely to benefit.

Study details

Main results from the SweDCIS trial, previously reported (J Clin Oncol. 2014;32:3613-8), showed that adjuvant radiation therapy reduced recurrences, yielding a 12% absolute reduction in risk of ipsilateral recurrence (10% for in situ recurrences and 2% for invasive recurrences).

For the validation study, Dr. Wärnberg and his colleagues were able to obtain tissue and biological signature results, blinded to patient outcome, for 56% of the original trial population. About half of patients each were determined to have low risk scores and elevated risk scores.

Among the 506 patients with clear margins, the score, analyzed as a continuous variable, was associated with risk of any (in situ or invasive) ipsilateral recurrence during follow-up (hazard ratio, 1.49 per 5-unit increase; P = .038).

In a multivariate model, receipt of radiation therapy was associated with a 52% relative reduction in 10-year risk of any ipsilateral recurrence for those with a low-risk score (HR, 0.48; P = .04) and a greater 69% relative reduction for those with an elevated risk score (HR, 0.31; P less than .001).

Radiation therapy did not significantly reduce the risk of ipsilateral invasive recurrence in the low risk group (HR, 0.84; P = .70), but it did in the elevated risk group (HR, 0.24; P = .012).

These findings essentially mirrored those of a 2015 validation study in a separate cohort of 526 patients from Uppsala University Hospital and the University of Massachusetts, according to Dr. Wärnberg. “We found highly consistent data with these two different sets,” he said.

Analyses additionally showed that radiation therapy reduced the 10-year risk of an invasive breast cancer recurrence by an absolute 1% for patients with low risk scores (not significant) but by an absolute 9% for patients with elevated risk scores (P = .012).

Dr. Wärnberg disclosed that he had no relevant conflicts of interest. The study was funded in part by PreludeDx.

SOURCE: Warnberg et al., SABCS Abstract GS5-08

SAN ANTONIO – A biological risk signature can help guide decisions about use of adjuvant radiation therapy in patients with ductal carcinoma in situ (DCIS), suggests a validation study reported at the San Antonio Breast Cancer Symposium.

Radiation therapy reduces the 10-year risk of any ipsilateral recurrence in this population by about 50% as established in a large overview of trials (J Natl Cancer Inst Monogr. 2010;2010:162-77), noted lead investigator Fredrik Wärnberg, MD, PhD, of Uppsala Academic Hospital, Uppsala University, Sweden. But factors such as tumor size, grade, and margins have not been helpful in identifying patients most likely to benefit.

Study details

Main results from the SweDCIS trial, previously reported (J Clin Oncol. 2014;32:3613-8), showed that adjuvant radiation therapy reduced recurrences, yielding a 12% absolute reduction in risk of ipsilateral recurrence (10% for in situ recurrences and 2% for invasive recurrences).

For the validation study, Dr. Wärnberg and his colleagues were able to obtain tissue and biological signature results, blinded to patient outcome, for 56% of the original trial population. About half of patients each were determined to have low risk scores and elevated risk scores.

Among the 506 patients with clear margins, the score, analyzed as a continuous variable, was associated with risk of any (in situ or invasive) ipsilateral recurrence during follow-up (hazard ratio, 1.49 per 5-unit increase; P = .038).

In a multivariate model, receipt of radiation therapy was associated with a 52% relative reduction in 10-year risk of any ipsilateral recurrence for those with a low-risk score (HR, 0.48; P = .04) and a greater 69% relative reduction for those with an elevated risk score (HR, 0.31; P less than .001).

Radiation therapy did not significantly reduce the risk of ipsilateral invasive recurrence in the low risk group (HR, 0.84; P = .70), but it did in the elevated risk group (HR, 0.24; P = .012).

These findings essentially mirrored those of a 2015 validation study in a separate cohort of 526 patients from Uppsala University Hospital and the University of Massachusetts, according to Dr. Wärnberg. “We found highly consistent data with these two different sets,” he said.

Analyses additionally showed that radiation therapy reduced the 10-year risk of an invasive breast cancer recurrence by an absolute 1% for patients with low risk scores (not significant) but by an absolute 9% for patients with elevated risk scores (P = .012).

Dr. Wärnberg disclosed that he had no relevant conflicts of interest. The study was funded in part by PreludeDx.

SOURCE: Warnberg et al., SABCS Abstract GS5-08

SAN ANTONIO – Postmenopausal women may be able to lower their risk of invasive breast cancer by simply losing some weight, according to an analysis of the large prospective Women’s Health Initiative Observational Study.

“While obesity is an established risk factor for postmenopausal breast cancer, studies of weight loss and breast cancer provide inconsistent results. It’s been very, very difficult to show that losing weight changes breast cancer incidence,” said lead investigator Rowan T. Chlebowski, MD, PhD, research professor in the department of medical oncology and therapeutics research at City of Hope in Duarte, Calif. “Consequently, the current public health message is limited to ‘avoid body fatness’ [N Engl J Med. 2016;375:794-8]. That’s not a very strong public health message.”

Susan London/Frontline Medical News

Parsing the findings

“I hope that you can present this to general doctors rather than oncologists because those are the ones seeing healthy women, by and large,” said press briefing moderator C. Kent Osborne, MD, codirector of SABCS and director of the Dan L. Duncan Cancer Center at Baylor College of Medicine in Houston. “But in my patients, I’ve always suggested that they lose weight. Most of them with breast cancer are overweight, it seems. And I always had to do it because of diabetes and other factors. Now we can do it because we have a breast cancer endpoint that also suggests that losing weight will help with that as well.”

Susan London/Frontline Medical News

Study details

The Women’s Health Initiative Observational Study recruited 93,676 postmenopausal women aged 50-79 years from 40 U.S. clinical centers during 1993-1998. The women had measurements taken of height and weight at baseline and at year 3 for calculation of BMI, and were asked about intentionality of any weight loss during that period.

Analyses were based on 61,335 women who had normal or higher body weight and were cancer free at baseline, survived at least 3 years, and had adequate data.

Overall, about 13.3% of women lost at least 5% of their body weight between baseline and year 3; 7.9% did so intentionally, losing an average of 19.6 pounds, and 5.5% did so unintentionally, losing an average of 16.9 pounds.

“We used the 5% decrease because this level has been shown to change some biochemical markers potentially associated with cancer. And it has been shown in a different study population, a randomized trial, to reduce the frequency of diabetes,” Dr. Chlebowski noted.

“There was nothing that the study did to induce the weight loss. And based on a partial look at the data, it doesn’t look like many of the women went to some kind of program to lose weight. So it was probably self-directed weight loss,” he noted. “Interestingly, the body mass index of this group was 29.9, so they were on the verge of going into obesity. We wondered in retrospect whether that was a motivating factor for them.”

In multivariate analysis, relative to peers having a stable weight over time, the women losing at least 5% of their weight had a lower risk of breast cancer (hazard ratio, 0.88; 95% confidence interval, 0.78-0.98; P = .02).

Findings were unchanged after further adjustment for mammography frequency. In addition, risk reduction was statistically indistinguishable whether the weight loss was intentional or not (P = .2 for interaction), and whether women were normal weight, overweight, or obese at baseline (P = .4 for interaction).

The 19.6% of women who had a weight gain of at least 5% did not have a significantly elevated risk of breast cancer overall, but they did have a significantly elevated risk of triple-negative breast cancer (HR, 1.54; 95% CI, 1.16-2.05). “We really don’t have a good explanation for this,” Dr. Chlebowski said.

Tackling the global obesity epidemic by conventional means to reduce cancer risk is an uphill battle, he concluded. “We are going to be looking for possible mediating factors. If you can find the mediating factors, pharmacologic intervention would have a much greater chance of success.”

Dr. Chlebowski disclosed that he had no relevant conflicts of interest. Research was supported by the National Heart, Lung and Blood Institute; National Institutes of Health; Department of Health and Human Services; and American Institute for Cancer Research.

SOURCE: Chlebowski et al., SABCS 2017 Abstract GS5-07

SAN ANTONIO – Postmenopausal women may be able to lower their risk of invasive breast cancer by simply losing some weight, according to an analysis of the large prospective Women’s Health Initiative Observational Study.

“While obesity is an established risk factor for postmenopausal breast cancer, studies of weight loss and breast cancer provide inconsistent results. It’s been very, very difficult to show that losing weight changes breast cancer incidence,” said lead investigator Rowan T. Chlebowski, MD, PhD, research professor in the department of medical oncology and therapeutics research at City of Hope in Duarte, Calif. “Consequently, the current public health message is limited to ‘avoid body fatness’ [N Engl J Med. 2016;375:794-8]. That’s not a very strong public health message.”

Susan London/Frontline Medical News

Parsing the findings

“I hope that you can present this to general doctors rather than oncologists because those are the ones seeing healthy women, by and large,” said press briefing moderator C. Kent Osborne, MD, codirector of SABCS and director of the Dan L. Duncan Cancer Center at Baylor College of Medicine in Houston. “But in my patients, I’ve always suggested that they lose weight. Most of them with breast cancer are overweight, it seems. And I always had to do it because of diabetes and other factors. Now we can do it because we have a breast cancer endpoint that also suggests that losing weight will help with that as well.”

Susan London/Frontline Medical News

Study details

The Women’s Health Initiative Observational Study recruited 93,676 postmenopausal women aged 50-79 years from 40 U.S. clinical centers during 1993-1998. The women had measurements taken of height and weight at baseline and at year 3 for calculation of BMI, and were asked about intentionality of any weight loss during that period.

Analyses were based on 61,335 women who had normal or higher body weight and were cancer free at baseline, survived at least 3 years, and had adequate data.

Overall, about 13.3% of women lost at least 5% of their body weight between baseline and year 3; 7.9% did so intentionally, losing an average of 19.6 pounds, and 5.5% did so unintentionally, losing an average of 16.9 pounds.

“We used the 5% decrease because this level has been shown to change some biochemical markers potentially associated with cancer. And it has been shown in a different study population, a randomized trial, to reduce the frequency of diabetes,” Dr. Chlebowski noted.

“There was nothing that the study did to induce the weight loss. And based on a partial look at the data, it doesn’t look like many of the women went to some kind of program to lose weight. So it was probably self-directed weight loss,” he noted. “Interestingly, the body mass index of this group was 29.9, so they were on the verge of going into obesity. We wondered in retrospect whether that was a motivating factor for them.”

In multivariate analysis, relative to peers having a stable weight over time, the women losing at least 5% of their weight had a lower risk of breast cancer (hazard ratio, 0.88; 95% confidence interval, 0.78-0.98; P = .02).

Findings were unchanged after further adjustment for mammography frequency. In addition, risk reduction was statistically indistinguishable whether the weight loss was intentional or not (P = .2 for interaction), and whether women were normal weight, overweight, or obese at baseline (P = .4 for interaction).

The 19.6% of women who had a weight gain of at least 5% did not have a significantly elevated risk of breast cancer overall, but they did have a significantly elevated risk of triple-negative breast cancer (HR, 1.54; 95% CI, 1.16-2.05). “We really don’t have a good explanation for this,” Dr. Chlebowski said.

Tackling the global obesity epidemic by conventional means to reduce cancer risk is an uphill battle, he concluded. “We are going to be looking for possible mediating factors. If you can find the mediating factors, pharmacologic intervention would have a much greater chance of success.”

Dr. Chlebowski disclosed that he had no relevant conflicts of interest. Research was supported by the National Heart, Lung and Blood Institute; National Institutes of Health; Department of Health and Human Services; and American Institute for Cancer Research.

SOURCE: Chlebowski et al., SABCS 2017 Abstract GS5-07

SAN ANTONIO – Postmenopausal women may be able to lower their risk of invasive breast cancer by simply losing some weight, according to an analysis of the large prospective Women’s Health Initiative Observational Study.

“While obesity is an established risk factor for postmenopausal breast cancer, studies of weight loss and breast cancer provide inconsistent results. It’s been very, very difficult to show that losing weight changes breast cancer incidence,” said lead investigator Rowan T. Chlebowski, MD, PhD, research professor in the department of medical oncology and therapeutics research at City of Hope in Duarte, Calif. “Consequently, the current public health message is limited to ‘avoid body fatness’ [N Engl J Med. 2016;375:794-8]. That’s not a very strong public health message.”

Susan London/Frontline Medical News

Parsing the findings

“I hope that you can present this to general doctors rather than oncologists because those are the ones seeing healthy women, by and large,” said press briefing moderator C. Kent Osborne, MD, codirector of SABCS and director of the Dan L. Duncan Cancer Center at Baylor College of Medicine in Houston. “But in my patients, I’ve always suggested that they lose weight. Most of them with breast cancer are overweight, it seems. And I always had to do it because of diabetes and other factors. Now we can do it because we have a breast cancer endpoint that also suggests that losing weight will help with that as well.”

Susan London/Frontline Medical News

Study details

The Women’s Health Initiative Observational Study recruited 93,676 postmenopausal women aged 50-79 years from 40 U.S. clinical centers during 1993-1998. The women had measurements taken of height and weight at baseline and at year 3 for calculation of BMI, and were asked about intentionality of any weight loss during that period.

Analyses were based on 61,335 women who had normal or higher body weight and were cancer free at baseline, survived at least 3 years, and had adequate data.

Overall, about 13.3% of women lost at least 5% of their body weight between baseline and year 3; 7.9% did so intentionally, losing an average of 19.6 pounds, and 5.5% did so unintentionally, losing an average of 16.9 pounds.

“We used the 5% decrease because this level has been shown to change some biochemical markers potentially associated with cancer. And it has been shown in a different study population, a randomized trial, to reduce the frequency of diabetes,” Dr. Chlebowski noted.

“There was nothing that the study did to induce the weight loss. And based on a partial look at the data, it doesn’t look like many of the women went to some kind of program to lose weight. So it was probably self-directed weight loss,” he noted. “Interestingly, the body mass index of this group was 29.9, so they were on the verge of going into obesity. We wondered in retrospect whether that was a motivating factor for them.”

In multivariate analysis, relative to peers having a stable weight over time, the women losing at least 5% of their weight had a lower risk of breast cancer (hazard ratio, 0.88; 95% confidence interval, 0.78-0.98; P = .02).

Findings were unchanged after further adjustment for mammography frequency. In addition, risk reduction was statistically indistinguishable whether the weight loss was intentional or not (P = .2 for interaction), and whether women were normal weight, overweight, or obese at baseline (P = .4 for interaction).

The 19.6% of women who had a weight gain of at least 5% did not have a significantly elevated risk of breast cancer overall, but they did have a significantly elevated risk of triple-negative breast cancer (HR, 1.54; 95% CI, 1.16-2.05). “We really don’t have a good explanation for this,” Dr. Chlebowski said.

Tackling the global obesity epidemic by conventional means to reduce cancer risk is an uphill battle, he concluded. “We are going to be looking for possible mediating factors. If you can find the mediating factors, pharmacologic intervention would have a much greater chance of success.”

Dr. Chlebowski disclosed that he had no relevant conflicts of interest. Research was supported by the National Heart, Lung and Blood Institute; National Institutes of Health; Department of Health and Human Services; and American Institute for Cancer Research.

SOURCE: Chlebowski et al., SABCS 2017 Abstract GS5-07