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It may not be always necessary to approach the treatment of HER2-positive, hormone receptor–negative (HER2+/HR–) early breast cancer with added chemotherapy, survival results of a prospective multicenter randomized trial suggest.
In the ADAPT-HER2+/HR– trial, comparing a de-escalated 12-week neoadjuvant regimen consisting of dual HER2 blockade with trastuzumab (Herceptin) and pertuzumab (Perjeta) with or without weekly paclitaxel, the three-drug regimen was associated with high pathologic complete response(pCR) rates and excellent 5-year survival, irrespective of whether patients received additional chemotherapy, reported Nadia Harbeck, MD, PhD, of the University of Munich.
“Chemotherapy-free regimens are promising in highly sensitive tumors with early response, but future investigation of such chemotherapy-free regimens need to be focused on selected patients, like those with HER2 3+ tumors, non–basal-like tumors, those showing early response to the de-escalated therapy, and those with predictive RNA signatures such as immune signatures,” she said in an oral abstract session during the American Society of Clinical Oncology annual meeting (Abstract 503).
Under the WGS umbrella
The ADAPT HER2+/HR– trial (NCT01779206) is one of several conducted by the West German Study Group (WGS) on therapy for intrinsic breast cancer types.
In this study, 134 patients with HER2-positive, estrogen and progesterone receptor–negative tumors with no metastatic disease and good performance status were assigned on a 5:2 basis to neoadjuvant therapy with trastuzumab at a loading dose of 8 mg/kg for the first cycle followed by 6 mg/kg for subsequent cycles every 3 weeks x 4, plus pertuzumab at a loading dose of 840 mg followed by 420 mg every 3 weeks x 4 (92 patients), or to trastuzumab and pertuzumab at the same dose and schedule plus paclitaxel 80 mg/m2 once weekly for 12 weeks.
Patients had surgery within 3 weeks of the end of study therapy unless they did not have a histologically confirmed pCR, in which case they went on to receive standard neoadjuvant therapy prior to surgery.
Adjuvant therapy was performed according to national guidelines, although patients with a pCR after 12 weeks of study therapy could be spared from adjuvant chemotherapy at the investigator’s discretion.
Patients underwent biopsy at 3 weeks for therapy for early response assessment, defined as either a Ki67 decrease of at least 30% from baseline, or low cellularity (less than 500 invasive tumor cells).
First survival results
The investigators previously reported the primary pCR endpoint from the trial, which showed a rate of 90% after 12 weeks in the three-drug arm, and a “substantial and clinically meaningful” pCR rate of 34% after the trastuzumab plus pertuzumab alone.
At ASCO 2021, Dr. Harbeck reported the first survival data from the trial.
After a median follow-up of 59.9 months, there were no statistically significant differences between trial arms in either overall survival, invasive disease-free survival (iDFS), or distant disease-free survival (dDFS).
The 5-year iDFS rate in the three-drug arm was 98%, compared with 87% for the dual HER2 blockade-only arm, a difference that was not statistically significant.
The 5-year dDFS rates were 98% and 92% respectively. There were only seven dDFS events during follow-up, Dr. Harbeck noted.
There were only six deaths during follow-up, with overall survival rates of 98% in the paclitaxel-containing arm, and 94% in the anti-HER2 antibodies–only arm, a difference of one overall survival event, Dr. Harbeck said.
pCR counts
However, patients who did not have pathologic complete responses at the end of first-line de-escalated therapy had worse outcomes, with a 5-year iDFS rate of 82%, compared with 98% for patients who had achieved a pCR. This translated into a hazard ratio for invasive disease in patients with pCRs of 0.14 (P = .011).
This difference occurred despite the study requirement that all patients who did not have pCR after 12 weeks of initial therapy would receive additional chemotherapy.
Looking at the tumor subtype among patients in the paclitaxel-free arm to see whether they could identify predictors of early response, the researchers found a pCR rate of 36.5% among 85 patients with nonbasal tumors, but 0% among 7 patients with basal tumors.
The investigators identified a population of patients whose tumors could be considered nonsensitive to dual HER2 blockade alone: Those with basal tumors, those tumors with low immunohistochemical HER2 expression, and those without an early response to therapy on biopsy 3 weeks into initial therapy. Among 31 of the 92 patients in the dual HER2 arm who met this description, 2 had pCRs, Dr. Harbeck noted.
The 5-year iDFS rate among patients in the dual blockade–only arm with nonsensitive tumors was 79%, compared with 93% for patients with treatment-responsive types, although there were only 13 invasive events total in this arm.
“If we look at the whole trial population, the negative prognostic impact of what we termed nonsensitive tumors was even significant regarding dDFS, with a hazard ratio of about 5,” she said.
‘A consistent theme’
Invited discussant Lisa A. Carey, MD, ScM, of the University of North Carolina Lineberger Comprehensive Cancer Center in Chapel Hill, noted that the trial was underpowered for outcomes, but that results nonetheless suggest that patients with strongly HER2-driven tumors might get comparable benefits from less chemotherapy.
“This trial included only hormone receptor–negative, HER2-positive tumors, and these we know are likely to be HER2-enriched in terms of subtype, about three-quarters of them,”she said.
The previously reported pCR rate of 90% in the paclitaxel-containing arm, with 80% of patients requiring no further chemotherapy, resulted in the excellent 5-year iDFS and dDFS in this group, despite the relatively highly clinical stage, with about 60% of patients having clinical stage 2 or higher tumors, and more than 40% being node positive.
The idea that pCR itself can predict which patients could be spared from more intensive chemotherapy “is starting to look like a consistent theme,” she said.
Dr. Carey pointed out that in the KRISTINE trial comparing the combination of trastuzumab emtansine (T-DM1) and pertuzumab with standard chemotherapy in patients with HER2-positive stage I-III breast cancer, although the experimental combination was associated with lower pCR rates and worse event-free survival, rates of iDFS/dDFS were virtually identical for patients in both arms who achieved a pCR.
“So the question is can pCR mean that we can either eliminate additional therapy,” she said, noting that the question is currently being addressed prospectively in two clinical trials, COMPASS-pCR and DECRESCENDO.
ADAPT HER2+/HR- is sponsored by F. Hoffman-La Roche. Dr. Harbeck disclosed institutional research funding from Roche/Genentech, as well as honoraria and consulting/advising for multiple companies. Dr. Carey disclosed institutional research funding and other relationships with various companies.
It may not be always necessary to approach the treatment of HER2-positive, hormone receptor–negative (HER2+/HR–) early breast cancer with added chemotherapy, survival results of a prospective multicenter randomized trial suggest.
In the ADAPT-HER2+/HR– trial, comparing a de-escalated 12-week neoadjuvant regimen consisting of dual HER2 blockade with trastuzumab (Herceptin) and pertuzumab (Perjeta) with or without weekly paclitaxel, the three-drug regimen was associated with high pathologic complete response(pCR) rates and excellent 5-year survival, irrespective of whether patients received additional chemotherapy, reported Nadia Harbeck, MD, PhD, of the University of Munich.
“Chemotherapy-free regimens are promising in highly sensitive tumors with early response, but future investigation of such chemotherapy-free regimens need to be focused on selected patients, like those with HER2 3+ tumors, non–basal-like tumors, those showing early response to the de-escalated therapy, and those with predictive RNA signatures such as immune signatures,” she said in an oral abstract session during the American Society of Clinical Oncology annual meeting (Abstract 503).
Under the WGS umbrella
The ADAPT HER2+/HR– trial (NCT01779206) is one of several conducted by the West German Study Group (WGS) on therapy for intrinsic breast cancer types.
In this study, 134 patients with HER2-positive, estrogen and progesterone receptor–negative tumors with no metastatic disease and good performance status were assigned on a 5:2 basis to neoadjuvant therapy with trastuzumab at a loading dose of 8 mg/kg for the first cycle followed by 6 mg/kg for subsequent cycles every 3 weeks x 4, plus pertuzumab at a loading dose of 840 mg followed by 420 mg every 3 weeks x 4 (92 patients), or to trastuzumab and pertuzumab at the same dose and schedule plus paclitaxel 80 mg/m2 once weekly for 12 weeks.
Patients had surgery within 3 weeks of the end of study therapy unless they did not have a histologically confirmed pCR, in which case they went on to receive standard neoadjuvant therapy prior to surgery.
Adjuvant therapy was performed according to national guidelines, although patients with a pCR after 12 weeks of study therapy could be spared from adjuvant chemotherapy at the investigator’s discretion.
Patients underwent biopsy at 3 weeks for therapy for early response assessment, defined as either a Ki67 decrease of at least 30% from baseline, or low cellularity (less than 500 invasive tumor cells).
First survival results
The investigators previously reported the primary pCR endpoint from the trial, which showed a rate of 90% after 12 weeks in the three-drug arm, and a “substantial and clinically meaningful” pCR rate of 34% after the trastuzumab plus pertuzumab alone.
At ASCO 2021, Dr. Harbeck reported the first survival data from the trial.
After a median follow-up of 59.9 months, there were no statistically significant differences between trial arms in either overall survival, invasive disease-free survival (iDFS), or distant disease-free survival (dDFS).
The 5-year iDFS rate in the three-drug arm was 98%, compared with 87% for the dual HER2 blockade-only arm, a difference that was not statistically significant.
The 5-year dDFS rates were 98% and 92% respectively. There were only seven dDFS events during follow-up, Dr. Harbeck noted.
There were only six deaths during follow-up, with overall survival rates of 98% in the paclitaxel-containing arm, and 94% in the anti-HER2 antibodies–only arm, a difference of one overall survival event, Dr. Harbeck said.
pCR counts
However, patients who did not have pathologic complete responses at the end of first-line de-escalated therapy had worse outcomes, with a 5-year iDFS rate of 82%, compared with 98% for patients who had achieved a pCR. This translated into a hazard ratio for invasive disease in patients with pCRs of 0.14 (P = .011).
This difference occurred despite the study requirement that all patients who did not have pCR after 12 weeks of initial therapy would receive additional chemotherapy.
Looking at the tumor subtype among patients in the paclitaxel-free arm to see whether they could identify predictors of early response, the researchers found a pCR rate of 36.5% among 85 patients with nonbasal tumors, but 0% among 7 patients with basal tumors.
The investigators identified a population of patients whose tumors could be considered nonsensitive to dual HER2 blockade alone: Those with basal tumors, those tumors with low immunohistochemical HER2 expression, and those without an early response to therapy on biopsy 3 weeks into initial therapy. Among 31 of the 92 patients in the dual HER2 arm who met this description, 2 had pCRs, Dr. Harbeck noted.
The 5-year iDFS rate among patients in the dual blockade–only arm with nonsensitive tumors was 79%, compared with 93% for patients with treatment-responsive types, although there were only 13 invasive events total in this arm.
“If we look at the whole trial population, the negative prognostic impact of what we termed nonsensitive tumors was even significant regarding dDFS, with a hazard ratio of about 5,” she said.
‘A consistent theme’
Invited discussant Lisa A. Carey, MD, ScM, of the University of North Carolina Lineberger Comprehensive Cancer Center in Chapel Hill, noted that the trial was underpowered for outcomes, but that results nonetheless suggest that patients with strongly HER2-driven tumors might get comparable benefits from less chemotherapy.
“This trial included only hormone receptor–negative, HER2-positive tumors, and these we know are likely to be HER2-enriched in terms of subtype, about three-quarters of them,”she said.
The previously reported pCR rate of 90% in the paclitaxel-containing arm, with 80% of patients requiring no further chemotherapy, resulted in the excellent 5-year iDFS and dDFS in this group, despite the relatively highly clinical stage, with about 60% of patients having clinical stage 2 or higher tumors, and more than 40% being node positive.
The idea that pCR itself can predict which patients could be spared from more intensive chemotherapy “is starting to look like a consistent theme,” she said.
Dr. Carey pointed out that in the KRISTINE trial comparing the combination of trastuzumab emtansine (T-DM1) and pertuzumab with standard chemotherapy in patients with HER2-positive stage I-III breast cancer, although the experimental combination was associated with lower pCR rates and worse event-free survival, rates of iDFS/dDFS were virtually identical for patients in both arms who achieved a pCR.
“So the question is can pCR mean that we can either eliminate additional therapy,” she said, noting that the question is currently being addressed prospectively in two clinical trials, COMPASS-pCR and DECRESCENDO.
ADAPT HER2+/HR- is sponsored by F. Hoffman-La Roche. Dr. Harbeck disclosed institutional research funding from Roche/Genentech, as well as honoraria and consulting/advising for multiple companies. Dr. Carey disclosed institutional research funding and other relationships with various companies.
It may not be always necessary to approach the treatment of HER2-positive, hormone receptor–negative (HER2+/HR–) early breast cancer with added chemotherapy, survival results of a prospective multicenter randomized trial suggest.
In the ADAPT-HER2+/HR– trial, comparing a de-escalated 12-week neoadjuvant regimen consisting of dual HER2 blockade with trastuzumab (Herceptin) and pertuzumab (Perjeta) with or without weekly paclitaxel, the three-drug regimen was associated with high pathologic complete response(pCR) rates and excellent 5-year survival, irrespective of whether patients received additional chemotherapy, reported Nadia Harbeck, MD, PhD, of the University of Munich.
“Chemotherapy-free regimens are promising in highly sensitive tumors with early response, but future investigation of such chemotherapy-free regimens need to be focused on selected patients, like those with HER2 3+ tumors, non–basal-like tumors, those showing early response to the de-escalated therapy, and those with predictive RNA signatures such as immune signatures,” she said in an oral abstract session during the American Society of Clinical Oncology annual meeting (Abstract 503).
Under the WGS umbrella
The ADAPT HER2+/HR– trial (NCT01779206) is one of several conducted by the West German Study Group (WGS) on therapy for intrinsic breast cancer types.
In this study, 134 patients with HER2-positive, estrogen and progesterone receptor–negative tumors with no metastatic disease and good performance status were assigned on a 5:2 basis to neoadjuvant therapy with trastuzumab at a loading dose of 8 mg/kg for the first cycle followed by 6 mg/kg for subsequent cycles every 3 weeks x 4, plus pertuzumab at a loading dose of 840 mg followed by 420 mg every 3 weeks x 4 (92 patients), or to trastuzumab and pertuzumab at the same dose and schedule plus paclitaxel 80 mg/m2 once weekly for 12 weeks.
Patients had surgery within 3 weeks of the end of study therapy unless they did not have a histologically confirmed pCR, in which case they went on to receive standard neoadjuvant therapy prior to surgery.
Adjuvant therapy was performed according to national guidelines, although patients with a pCR after 12 weeks of study therapy could be spared from adjuvant chemotherapy at the investigator’s discretion.
Patients underwent biopsy at 3 weeks for therapy for early response assessment, defined as either a Ki67 decrease of at least 30% from baseline, or low cellularity (less than 500 invasive tumor cells).
First survival results
The investigators previously reported the primary pCR endpoint from the trial, which showed a rate of 90% after 12 weeks in the three-drug arm, and a “substantial and clinically meaningful” pCR rate of 34% after the trastuzumab plus pertuzumab alone.
At ASCO 2021, Dr. Harbeck reported the first survival data from the trial.
After a median follow-up of 59.9 months, there were no statistically significant differences between trial arms in either overall survival, invasive disease-free survival (iDFS), or distant disease-free survival (dDFS).
The 5-year iDFS rate in the three-drug arm was 98%, compared with 87% for the dual HER2 blockade-only arm, a difference that was not statistically significant.
The 5-year dDFS rates were 98% and 92% respectively. There were only seven dDFS events during follow-up, Dr. Harbeck noted.
There were only six deaths during follow-up, with overall survival rates of 98% in the paclitaxel-containing arm, and 94% in the anti-HER2 antibodies–only arm, a difference of one overall survival event, Dr. Harbeck said.
pCR counts
However, patients who did not have pathologic complete responses at the end of first-line de-escalated therapy had worse outcomes, with a 5-year iDFS rate of 82%, compared with 98% for patients who had achieved a pCR. This translated into a hazard ratio for invasive disease in patients with pCRs of 0.14 (P = .011).
This difference occurred despite the study requirement that all patients who did not have pCR after 12 weeks of initial therapy would receive additional chemotherapy.
Looking at the tumor subtype among patients in the paclitaxel-free arm to see whether they could identify predictors of early response, the researchers found a pCR rate of 36.5% among 85 patients with nonbasal tumors, but 0% among 7 patients with basal tumors.
The investigators identified a population of patients whose tumors could be considered nonsensitive to dual HER2 blockade alone: Those with basal tumors, those tumors with low immunohistochemical HER2 expression, and those without an early response to therapy on biopsy 3 weeks into initial therapy. Among 31 of the 92 patients in the dual HER2 arm who met this description, 2 had pCRs, Dr. Harbeck noted.
The 5-year iDFS rate among patients in the dual blockade–only arm with nonsensitive tumors was 79%, compared with 93% for patients with treatment-responsive types, although there were only 13 invasive events total in this arm.
“If we look at the whole trial population, the negative prognostic impact of what we termed nonsensitive tumors was even significant regarding dDFS, with a hazard ratio of about 5,” she said.
‘A consistent theme’
Invited discussant Lisa A. Carey, MD, ScM, of the University of North Carolina Lineberger Comprehensive Cancer Center in Chapel Hill, noted that the trial was underpowered for outcomes, but that results nonetheless suggest that patients with strongly HER2-driven tumors might get comparable benefits from less chemotherapy.
“This trial included only hormone receptor–negative, HER2-positive tumors, and these we know are likely to be HER2-enriched in terms of subtype, about three-quarters of them,”she said.
The previously reported pCR rate of 90% in the paclitaxel-containing arm, with 80% of patients requiring no further chemotherapy, resulted in the excellent 5-year iDFS and dDFS in this group, despite the relatively highly clinical stage, with about 60% of patients having clinical stage 2 or higher tumors, and more than 40% being node positive.
The idea that pCR itself can predict which patients could be spared from more intensive chemotherapy “is starting to look like a consistent theme,” she said.
Dr. Carey pointed out that in the KRISTINE trial comparing the combination of trastuzumab emtansine (T-DM1) and pertuzumab with standard chemotherapy in patients with HER2-positive stage I-III breast cancer, although the experimental combination was associated with lower pCR rates and worse event-free survival, rates of iDFS/dDFS were virtually identical for patients in both arms who achieved a pCR.
“So the question is can pCR mean that we can either eliminate additional therapy,” she said, noting that the question is currently being addressed prospectively in two clinical trials, COMPASS-pCR and DECRESCENDO.
ADAPT HER2+/HR- is sponsored by F. Hoffman-La Roche. Dr. Harbeck disclosed institutional research funding from Roche/Genentech, as well as honoraria and consulting/advising for multiple companies. Dr. Carey disclosed institutional research funding and other relationships with various companies.
FROM ASCO 2021