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based on final data from a randomized trial.
The IMpassion031 trial showed significant improvement in pathological complete response (pCR) with the addition of atezolizumab to chemotherapy, as well as an acceptable safety profile, said Carlos H. Barrios, MD, of the Latin American Cooperative Oncology Group, Oncoclinicas, in Porto Allegre, Brazil, at the European Society for Medical Oncology (ESMO) Breast Cancer annual congress. Those findings were published in the Lancet in 2020.
Dr. Barrios reported data from a final analysis of the IMpassion031 trial, with data on event-free survival (EFS), disease-free survival (DFS) and overall survival (OS) in the intent-to-treat (ITT) and PD-L1–positive populations.
In the study, patients with early triple-negative breast cancer (eTNBC) and a primary tumor greater than 2 cm were randomized to 840 mg of atezolizumab once every 2 weeks plus a neoadjuvant chemotherapy regimen of nab-paclitaxel 125 mg/m2 once weekly for 12 weeks, followed by doxorubicin 60 mg/m2 plus cyclophosphamide 600 mg/m2 once every 2 weeks for 8 weeks. A total of 333 patients were randomized (165 atezolizumab and 168 placebo). Patients were stratified by stage II versus stage III, and by status of PD-L1, a protein that can predict treatment response (PD-L1 less than 1% vs. 1% or higher).
The primary endpoints (previously reported) were pathological complete response (pCR) in the ITT and PD-L1 populations. After a median follow-up of 39 months, the pCR was 58% in patients treated with atezolizumab versus 41% in those treated with neoadjuvant chemotherapy alone (P = .0044) in the ITT population, Dr. Barrios said. The added benefit from atezolizumab occurred regardless of the status of PD-L1.
Dr. Barrios reported the secondary outcomes of EFS, DFS, and OS in the intent-to-treat and PD-L1–positive populations. “This is a descriptive analysis, with no statistical comparison,” he emphasized.
The 2-year data on EFS, DFS, and OS consistently favored atezolizumab across key clinical subgroups, Dr. Barrios said. In the ITT population, 2-year EFS, DFS, and OS was 85%, 87%, and 95%, respectively, in the atezolizumab group and 80%, 83%, and 90%, respectively, in the placebo group. The results were similar, irrespective of PD-L1 status.
In the PD-L1–positive population, 2-year EFS, DFS, and OS was 89%, 91%, and 95%, respectively, in atezolizumab patients and 80%, 87%, and 91% in placebo patients.
Among patients without pCR at the time of surgery, 14 of 70 patients (20%) in the atezolizumab group and 33 of 99 patients (33%) in the placebo group received additional adjuvant systemic therapy. The most common adjunctive therapy was capecitabine.
As for safety, no new safety signals or treatment-related deaths were observed in the study. Overall, 70% of atezolizumab patients and 62% of placebo patients experienced grade 3 or 4 adverse events (AEs); 59% and 54% of which were treatment related. A total of 1% of patients in each group experienced grade 5 AEs. A total of 25% of atezolizumab patients and 20% of placebo patients experienced AEs leading to treatment discontinuation.
In a further exploratory analysis, pCR was highly predictive of long-term outcomes. Exploratory analysis of circulating tumor DNA (ctDNA) showed clearance in 89% of atezolizumab patients and 86% of placebo patients by the time of surgery.
Looking at the relationship between ctDNA, DFS, and OS, positive ctDNA was associated with a worse prognosis following surgery. As demonstrated in previous studies, pCR patients with negative ctDNA had the best DFS and OS. “In non-pCR patients with positive ctDNA, a numerical trend suggests improved overall survival with atezolizumab,” although the caveat is the very small numbers, Dr. Barrios said.
More research is needed, but in the final analysis, the significant pCR benefit seen with the addition of atezolizumab to chemotherapy for eTNBC translated into numerically improved EFS, DFS and OS, said Dr. Barrios. Additionally, “we should further analyze ctDNA to help select patients for further therapy.”
In a question-and-answer session, Dr. Barrios was asked how the results compared with other studies.
“We should not overinterpret the results,” he said. However, “what the IMpassion031 study shows is consistency; the results are aligned with previous studies addressing the same question of introducing immunotherapy,” in the patient population. Although the numbers in the IMpassion031 study did not reach statistical significance, it is important to recognize that they reflect previous research.
“In my opinion, looking at the whole field, immunotherapy is something we need to consider as part of the treatment of these patients,” said Dr. Barrios. However, more research is needed to better identify which patients do and do not need chemotherapy.
Phase 2 data show increased response with added atezolizumab for PD-L1–negative patients
In a second study known as ABSCG-52/ATHENE, researchers evaluated neoadjuvant atezolizumab in combination with dual HER2 blockade plus epirubicin for the treatment of patients with early HER2-positive breast cancer.
For most of these patients, the current standard of care is neoadjuvant dual HER2 blockade with trastuzumab (T) and pertuzumab (P) plus poly-chemotherapy, said Gabriel Rinnerthaler, MD, of the Salzburg (Austria) Cancer Research Institute, said in his presentation at the meeting. However, de-escalation of chemotherapy has been a major focus of research in recent years, and more research is needed on a combination of anthracyclines, such as epirubicin and idarubicin, and immune-checkpoint modulators.
In the phase 2 study, the researchers randomized patients with previously untreated, histologically confirmed HER2-positive early breast cancer (defined as a clinical prognostic stage cT1c–4a-d, N0-3, M0) in a 1:1 ratio to two 3-weekly cycles of a chemotherapy-free induction phase (part 1) with TP plus 1,200 mg atezolizumab (TP-A) or TP alone.
“We hypothesized that the additive effect of immune checkpoint inhibitors plus anti-HER2 therapy and chemotherapy would not be linear,” he said.
At the end of this period, all patients underwent four cycles of TP-A in combination with epirubicin (part 2). The primary endpoint was pCR (defined as absence of invasive cancer in the breast and axillary nodes, or ypT0/Tis ypN0) in the overall study population, and a pCR of 40% was considered a positive result.
A total of 29 patients were randomized to TP-A and 29 to TP alone in nine treatment centers in Austria. The study population ranged from 33 to 82 years, with a median age of 57 years. Most patients (72.4%) had hormone receptor (HR)–positive tumors; a total of 45 patients had stage IIA cancer, and 13 had stage IIB.
The primary endpoint of pCR occurred in 35 patients overall (60.3%). In a univariate analysis, the response rates were lower in HR-positive patients, in premenopausal patients, and in histologies other than NST (invasive carcinoma of no special type), Dr. Rinnerthaler said, but none of the differences were statistically significant, likely because of the small numbers in each group.
In an exploratory analysis of the ITT population with available PD-L1 data, the pCR was 69.2% for PD-L1–negative patients and 55.2% for PD-L1–positive patients.
“We observed the highest pCR rates in PD-L1–negative patients treated in the TP-A group and the lowest in PD-L1–positive patients treated with TP alone,” Dr. Rinnerthaler said.
No new safety concerns were observed during the study, Dr. Rinnerthaler noted. AEs of grade 3 or higher occurred in 17 patients (29.3%), including 9 in the TP-A group and 8 in the TP group. The most common AEs in both groups were nausea, diarrhea, and fatigue. No AEs of special interest of grade 3 or higher (defined as immune-related AEs, cardiac disorders, or infusion-related reactions) were observed.
The study findings were limited by the small sample size, but the resulting pCR rate of 60.3% was higher than the predefined threshold of 40% and supports additional research, said Dr. Rinnerthaler.
“For HER2-positive early breast cancer, a neoadjuvant chemotherapy de-escalation immunotherapy regimen with trastuzumab, pertuzumab, atezolizumab, and epirubicin is highly effective and safe and merits further investigation,” he concluded.
During a question-and-answer session, Dr. Rinnerthaler was asked why pCR increased in PD-L1 negative patients.
Previous data have shown that PD-L1 is up-regulated in certain tumors, and may serve as a surrogate for sensitivity, he said. In previous studies the additional effect of atezolizumab was seen in a PD-L1–negative group.
Dr. Rinnerthaler said he hopes to clarify this question when his research team reviews biopsy data from baseline and after the induction phase.
Defining response is key to de-escalation
In the IMpassion031 trial, “what we saw is a tendency to better outcomes for those patients who received atezolizumab,” said Matteo Lambertini, MD, of the University of Genova (Italy), who served as discussant for the two studies. The IMpassion031 study raises the question of where we are in the use of immuno-oncology for eTNBC. The study is now one of five neoadjuvant trials in this population.
Dr. Lambertini cited the KEYNOTE-522 study, which showed significant results in EFS. However, sample sizes and statistical design were different between these studies. “I think we need large studies of data in the adjuvant and postneoadjuvant setting for patients with triple-negative breast cancer.”
Postneoadjuvant considerations from the IMpassion031 trial showed good outcomes with no additional benefit of an immune checkpoint inhibitors.
For those patients with a pCR, it is definitely time to de-escalate treatment,” he said. In patients without pCR, escalation is needed, but an improved definition of pCR is also needed.
With regard to the ATHENE study, “it may be considered a positive study because the threshold of 40% was reached,” he said. The question is what is the optimum chemotherapy backbone. There appears to be no added benefit to adding an immune checkpoint inhibitor.
There are needs for defining the role of immunotherapy in HER2-positive breast cancer and more biomarker research to inform patient selection and study design, he said.
Finally, “I am not sure that the addition of an immune checkpoint inhibitor can be considered a de-escalation,” he noted.
IMpassion031 was supported by F. Hoffmann–La Roche. Dr. Barrio disclosed financial relationships with numerous companies. ABSCG-52/ATHENE was supported by the Austrian Breast and Colorectal Cancer Study Group and Roche Austria. Dr. Rinnerthaler disclosed relationships with multiple companies including Amgen, Daiichi Sankyo, Lilly, Gilead, MSD, Novartis, Pfizer, Roche, Seagen, and Pierre Fabre. Dr. Lambertini disclosed relationships with multiple companies including Roche, Novartis, AstraZeneca, Lilly, Exact Sciences, Pfizer, MSD, Seagen, Gilead, Takeda, Sandoz, Ipsen, Libbs, Knight, and Daiichi Sankyo.
based on final data from a randomized trial.
The IMpassion031 trial showed significant improvement in pathological complete response (pCR) with the addition of atezolizumab to chemotherapy, as well as an acceptable safety profile, said Carlos H. Barrios, MD, of the Latin American Cooperative Oncology Group, Oncoclinicas, in Porto Allegre, Brazil, at the European Society for Medical Oncology (ESMO) Breast Cancer annual congress. Those findings were published in the Lancet in 2020.
Dr. Barrios reported data from a final analysis of the IMpassion031 trial, with data on event-free survival (EFS), disease-free survival (DFS) and overall survival (OS) in the intent-to-treat (ITT) and PD-L1–positive populations.
In the study, patients with early triple-negative breast cancer (eTNBC) and a primary tumor greater than 2 cm were randomized to 840 mg of atezolizumab once every 2 weeks plus a neoadjuvant chemotherapy regimen of nab-paclitaxel 125 mg/m2 once weekly for 12 weeks, followed by doxorubicin 60 mg/m2 plus cyclophosphamide 600 mg/m2 once every 2 weeks for 8 weeks. A total of 333 patients were randomized (165 atezolizumab and 168 placebo). Patients were stratified by stage II versus stage III, and by status of PD-L1, a protein that can predict treatment response (PD-L1 less than 1% vs. 1% or higher).
The primary endpoints (previously reported) were pathological complete response (pCR) in the ITT and PD-L1 populations. After a median follow-up of 39 months, the pCR was 58% in patients treated with atezolizumab versus 41% in those treated with neoadjuvant chemotherapy alone (P = .0044) in the ITT population, Dr. Barrios said. The added benefit from atezolizumab occurred regardless of the status of PD-L1.
Dr. Barrios reported the secondary outcomes of EFS, DFS, and OS in the intent-to-treat and PD-L1–positive populations. “This is a descriptive analysis, with no statistical comparison,” he emphasized.
The 2-year data on EFS, DFS, and OS consistently favored atezolizumab across key clinical subgroups, Dr. Barrios said. In the ITT population, 2-year EFS, DFS, and OS was 85%, 87%, and 95%, respectively, in the atezolizumab group and 80%, 83%, and 90%, respectively, in the placebo group. The results were similar, irrespective of PD-L1 status.
In the PD-L1–positive population, 2-year EFS, DFS, and OS was 89%, 91%, and 95%, respectively, in atezolizumab patients and 80%, 87%, and 91% in placebo patients.
Among patients without pCR at the time of surgery, 14 of 70 patients (20%) in the atezolizumab group and 33 of 99 patients (33%) in the placebo group received additional adjuvant systemic therapy. The most common adjunctive therapy was capecitabine.
As for safety, no new safety signals or treatment-related deaths were observed in the study. Overall, 70% of atezolizumab patients and 62% of placebo patients experienced grade 3 or 4 adverse events (AEs); 59% and 54% of which were treatment related. A total of 1% of patients in each group experienced grade 5 AEs. A total of 25% of atezolizumab patients and 20% of placebo patients experienced AEs leading to treatment discontinuation.
In a further exploratory analysis, pCR was highly predictive of long-term outcomes. Exploratory analysis of circulating tumor DNA (ctDNA) showed clearance in 89% of atezolizumab patients and 86% of placebo patients by the time of surgery.
Looking at the relationship between ctDNA, DFS, and OS, positive ctDNA was associated with a worse prognosis following surgery. As demonstrated in previous studies, pCR patients with negative ctDNA had the best DFS and OS. “In non-pCR patients with positive ctDNA, a numerical trend suggests improved overall survival with atezolizumab,” although the caveat is the very small numbers, Dr. Barrios said.
More research is needed, but in the final analysis, the significant pCR benefit seen with the addition of atezolizumab to chemotherapy for eTNBC translated into numerically improved EFS, DFS and OS, said Dr. Barrios. Additionally, “we should further analyze ctDNA to help select patients for further therapy.”
In a question-and-answer session, Dr. Barrios was asked how the results compared with other studies.
“We should not overinterpret the results,” he said. However, “what the IMpassion031 study shows is consistency; the results are aligned with previous studies addressing the same question of introducing immunotherapy,” in the patient population. Although the numbers in the IMpassion031 study did not reach statistical significance, it is important to recognize that they reflect previous research.
“In my opinion, looking at the whole field, immunotherapy is something we need to consider as part of the treatment of these patients,” said Dr. Barrios. However, more research is needed to better identify which patients do and do not need chemotherapy.
Phase 2 data show increased response with added atezolizumab for PD-L1–negative patients
In a second study known as ABSCG-52/ATHENE, researchers evaluated neoadjuvant atezolizumab in combination with dual HER2 blockade plus epirubicin for the treatment of patients with early HER2-positive breast cancer.
For most of these patients, the current standard of care is neoadjuvant dual HER2 blockade with trastuzumab (T) and pertuzumab (P) plus poly-chemotherapy, said Gabriel Rinnerthaler, MD, of the Salzburg (Austria) Cancer Research Institute, said in his presentation at the meeting. However, de-escalation of chemotherapy has been a major focus of research in recent years, and more research is needed on a combination of anthracyclines, such as epirubicin and idarubicin, and immune-checkpoint modulators.
In the phase 2 study, the researchers randomized patients with previously untreated, histologically confirmed HER2-positive early breast cancer (defined as a clinical prognostic stage cT1c–4a-d, N0-3, M0) in a 1:1 ratio to two 3-weekly cycles of a chemotherapy-free induction phase (part 1) with TP plus 1,200 mg atezolizumab (TP-A) or TP alone.
“We hypothesized that the additive effect of immune checkpoint inhibitors plus anti-HER2 therapy and chemotherapy would not be linear,” he said.
At the end of this period, all patients underwent four cycles of TP-A in combination with epirubicin (part 2). The primary endpoint was pCR (defined as absence of invasive cancer in the breast and axillary nodes, or ypT0/Tis ypN0) in the overall study population, and a pCR of 40% was considered a positive result.
A total of 29 patients were randomized to TP-A and 29 to TP alone in nine treatment centers in Austria. The study population ranged from 33 to 82 years, with a median age of 57 years. Most patients (72.4%) had hormone receptor (HR)–positive tumors; a total of 45 patients had stage IIA cancer, and 13 had stage IIB.
The primary endpoint of pCR occurred in 35 patients overall (60.3%). In a univariate analysis, the response rates were lower in HR-positive patients, in premenopausal patients, and in histologies other than NST (invasive carcinoma of no special type), Dr. Rinnerthaler said, but none of the differences were statistically significant, likely because of the small numbers in each group.
In an exploratory analysis of the ITT population with available PD-L1 data, the pCR was 69.2% for PD-L1–negative patients and 55.2% for PD-L1–positive patients.
“We observed the highest pCR rates in PD-L1–negative patients treated in the TP-A group and the lowest in PD-L1–positive patients treated with TP alone,” Dr. Rinnerthaler said.
No new safety concerns were observed during the study, Dr. Rinnerthaler noted. AEs of grade 3 or higher occurred in 17 patients (29.3%), including 9 in the TP-A group and 8 in the TP group. The most common AEs in both groups were nausea, diarrhea, and fatigue. No AEs of special interest of grade 3 or higher (defined as immune-related AEs, cardiac disorders, or infusion-related reactions) were observed.
The study findings were limited by the small sample size, but the resulting pCR rate of 60.3% was higher than the predefined threshold of 40% and supports additional research, said Dr. Rinnerthaler.
“For HER2-positive early breast cancer, a neoadjuvant chemotherapy de-escalation immunotherapy regimen with trastuzumab, pertuzumab, atezolizumab, and epirubicin is highly effective and safe and merits further investigation,” he concluded.
During a question-and-answer session, Dr. Rinnerthaler was asked why pCR increased in PD-L1 negative patients.
Previous data have shown that PD-L1 is up-regulated in certain tumors, and may serve as a surrogate for sensitivity, he said. In previous studies the additional effect of atezolizumab was seen in a PD-L1–negative group.
Dr. Rinnerthaler said he hopes to clarify this question when his research team reviews biopsy data from baseline and after the induction phase.
Defining response is key to de-escalation
In the IMpassion031 trial, “what we saw is a tendency to better outcomes for those patients who received atezolizumab,” said Matteo Lambertini, MD, of the University of Genova (Italy), who served as discussant for the two studies. The IMpassion031 study raises the question of where we are in the use of immuno-oncology for eTNBC. The study is now one of five neoadjuvant trials in this population.
Dr. Lambertini cited the KEYNOTE-522 study, which showed significant results in EFS. However, sample sizes and statistical design were different between these studies. “I think we need large studies of data in the adjuvant and postneoadjuvant setting for patients with triple-negative breast cancer.”
Postneoadjuvant considerations from the IMpassion031 trial showed good outcomes with no additional benefit of an immune checkpoint inhibitors.
For those patients with a pCR, it is definitely time to de-escalate treatment,” he said. In patients without pCR, escalation is needed, but an improved definition of pCR is also needed.
With regard to the ATHENE study, “it may be considered a positive study because the threshold of 40% was reached,” he said. The question is what is the optimum chemotherapy backbone. There appears to be no added benefit to adding an immune checkpoint inhibitor.
There are needs for defining the role of immunotherapy in HER2-positive breast cancer and more biomarker research to inform patient selection and study design, he said.
Finally, “I am not sure that the addition of an immune checkpoint inhibitor can be considered a de-escalation,” he noted.
IMpassion031 was supported by F. Hoffmann–La Roche. Dr. Barrio disclosed financial relationships with numerous companies. ABSCG-52/ATHENE was supported by the Austrian Breast and Colorectal Cancer Study Group and Roche Austria. Dr. Rinnerthaler disclosed relationships with multiple companies including Amgen, Daiichi Sankyo, Lilly, Gilead, MSD, Novartis, Pfizer, Roche, Seagen, and Pierre Fabre. Dr. Lambertini disclosed relationships with multiple companies including Roche, Novartis, AstraZeneca, Lilly, Exact Sciences, Pfizer, MSD, Seagen, Gilead, Takeda, Sandoz, Ipsen, Libbs, Knight, and Daiichi Sankyo.
based on final data from a randomized trial.
The IMpassion031 trial showed significant improvement in pathological complete response (pCR) with the addition of atezolizumab to chemotherapy, as well as an acceptable safety profile, said Carlos H. Barrios, MD, of the Latin American Cooperative Oncology Group, Oncoclinicas, in Porto Allegre, Brazil, at the European Society for Medical Oncology (ESMO) Breast Cancer annual congress. Those findings were published in the Lancet in 2020.
Dr. Barrios reported data from a final analysis of the IMpassion031 trial, with data on event-free survival (EFS), disease-free survival (DFS) and overall survival (OS) in the intent-to-treat (ITT) and PD-L1–positive populations.
In the study, patients with early triple-negative breast cancer (eTNBC) and a primary tumor greater than 2 cm were randomized to 840 mg of atezolizumab once every 2 weeks plus a neoadjuvant chemotherapy regimen of nab-paclitaxel 125 mg/m2 once weekly for 12 weeks, followed by doxorubicin 60 mg/m2 plus cyclophosphamide 600 mg/m2 once every 2 weeks for 8 weeks. A total of 333 patients were randomized (165 atezolizumab and 168 placebo). Patients were stratified by stage II versus stage III, and by status of PD-L1, a protein that can predict treatment response (PD-L1 less than 1% vs. 1% or higher).
The primary endpoints (previously reported) were pathological complete response (pCR) in the ITT and PD-L1 populations. After a median follow-up of 39 months, the pCR was 58% in patients treated with atezolizumab versus 41% in those treated with neoadjuvant chemotherapy alone (P = .0044) in the ITT population, Dr. Barrios said. The added benefit from atezolizumab occurred regardless of the status of PD-L1.
Dr. Barrios reported the secondary outcomes of EFS, DFS, and OS in the intent-to-treat and PD-L1–positive populations. “This is a descriptive analysis, with no statistical comparison,” he emphasized.
The 2-year data on EFS, DFS, and OS consistently favored atezolizumab across key clinical subgroups, Dr. Barrios said. In the ITT population, 2-year EFS, DFS, and OS was 85%, 87%, and 95%, respectively, in the atezolizumab group and 80%, 83%, and 90%, respectively, in the placebo group. The results were similar, irrespective of PD-L1 status.
In the PD-L1–positive population, 2-year EFS, DFS, and OS was 89%, 91%, and 95%, respectively, in atezolizumab patients and 80%, 87%, and 91% in placebo patients.
Among patients without pCR at the time of surgery, 14 of 70 patients (20%) in the atezolizumab group and 33 of 99 patients (33%) in the placebo group received additional adjuvant systemic therapy. The most common adjunctive therapy was capecitabine.
As for safety, no new safety signals or treatment-related deaths were observed in the study. Overall, 70% of atezolizumab patients and 62% of placebo patients experienced grade 3 or 4 adverse events (AEs); 59% and 54% of which were treatment related. A total of 1% of patients in each group experienced grade 5 AEs. A total of 25% of atezolizumab patients and 20% of placebo patients experienced AEs leading to treatment discontinuation.
In a further exploratory analysis, pCR was highly predictive of long-term outcomes. Exploratory analysis of circulating tumor DNA (ctDNA) showed clearance in 89% of atezolizumab patients and 86% of placebo patients by the time of surgery.
Looking at the relationship between ctDNA, DFS, and OS, positive ctDNA was associated with a worse prognosis following surgery. As demonstrated in previous studies, pCR patients with negative ctDNA had the best DFS and OS. “In non-pCR patients with positive ctDNA, a numerical trend suggests improved overall survival with atezolizumab,” although the caveat is the very small numbers, Dr. Barrios said.
More research is needed, but in the final analysis, the significant pCR benefit seen with the addition of atezolizumab to chemotherapy for eTNBC translated into numerically improved EFS, DFS and OS, said Dr. Barrios. Additionally, “we should further analyze ctDNA to help select patients for further therapy.”
In a question-and-answer session, Dr. Barrios was asked how the results compared with other studies.
“We should not overinterpret the results,” he said. However, “what the IMpassion031 study shows is consistency; the results are aligned with previous studies addressing the same question of introducing immunotherapy,” in the patient population. Although the numbers in the IMpassion031 study did not reach statistical significance, it is important to recognize that they reflect previous research.
“In my opinion, looking at the whole field, immunotherapy is something we need to consider as part of the treatment of these patients,” said Dr. Barrios. However, more research is needed to better identify which patients do and do not need chemotherapy.
Phase 2 data show increased response with added atezolizumab for PD-L1–negative patients
In a second study known as ABSCG-52/ATHENE, researchers evaluated neoadjuvant atezolizumab in combination with dual HER2 blockade plus epirubicin for the treatment of patients with early HER2-positive breast cancer.
For most of these patients, the current standard of care is neoadjuvant dual HER2 blockade with trastuzumab (T) and pertuzumab (P) plus poly-chemotherapy, said Gabriel Rinnerthaler, MD, of the Salzburg (Austria) Cancer Research Institute, said in his presentation at the meeting. However, de-escalation of chemotherapy has been a major focus of research in recent years, and more research is needed on a combination of anthracyclines, such as epirubicin and idarubicin, and immune-checkpoint modulators.
In the phase 2 study, the researchers randomized patients with previously untreated, histologically confirmed HER2-positive early breast cancer (defined as a clinical prognostic stage cT1c–4a-d, N0-3, M0) in a 1:1 ratio to two 3-weekly cycles of a chemotherapy-free induction phase (part 1) with TP plus 1,200 mg atezolizumab (TP-A) or TP alone.
“We hypothesized that the additive effect of immune checkpoint inhibitors plus anti-HER2 therapy and chemotherapy would not be linear,” he said.
At the end of this period, all patients underwent four cycles of TP-A in combination with epirubicin (part 2). The primary endpoint was pCR (defined as absence of invasive cancer in the breast and axillary nodes, or ypT0/Tis ypN0) in the overall study population, and a pCR of 40% was considered a positive result.
A total of 29 patients were randomized to TP-A and 29 to TP alone in nine treatment centers in Austria. The study population ranged from 33 to 82 years, with a median age of 57 years. Most patients (72.4%) had hormone receptor (HR)–positive tumors; a total of 45 patients had stage IIA cancer, and 13 had stage IIB.
The primary endpoint of pCR occurred in 35 patients overall (60.3%). In a univariate analysis, the response rates were lower in HR-positive patients, in premenopausal patients, and in histologies other than NST (invasive carcinoma of no special type), Dr. Rinnerthaler said, but none of the differences were statistically significant, likely because of the small numbers in each group.
In an exploratory analysis of the ITT population with available PD-L1 data, the pCR was 69.2% for PD-L1–negative patients and 55.2% for PD-L1–positive patients.
“We observed the highest pCR rates in PD-L1–negative patients treated in the TP-A group and the lowest in PD-L1–positive patients treated with TP alone,” Dr. Rinnerthaler said.
No new safety concerns were observed during the study, Dr. Rinnerthaler noted. AEs of grade 3 or higher occurred in 17 patients (29.3%), including 9 in the TP-A group and 8 in the TP group. The most common AEs in both groups were nausea, diarrhea, and fatigue. No AEs of special interest of grade 3 or higher (defined as immune-related AEs, cardiac disorders, or infusion-related reactions) were observed.
The study findings were limited by the small sample size, but the resulting pCR rate of 60.3% was higher than the predefined threshold of 40% and supports additional research, said Dr. Rinnerthaler.
“For HER2-positive early breast cancer, a neoadjuvant chemotherapy de-escalation immunotherapy regimen with trastuzumab, pertuzumab, atezolizumab, and epirubicin is highly effective and safe and merits further investigation,” he concluded.
During a question-and-answer session, Dr. Rinnerthaler was asked why pCR increased in PD-L1 negative patients.
Previous data have shown that PD-L1 is up-regulated in certain tumors, and may serve as a surrogate for sensitivity, he said. In previous studies the additional effect of atezolizumab was seen in a PD-L1–negative group.
Dr. Rinnerthaler said he hopes to clarify this question when his research team reviews biopsy data from baseline and after the induction phase.
Defining response is key to de-escalation
In the IMpassion031 trial, “what we saw is a tendency to better outcomes for those patients who received atezolizumab,” said Matteo Lambertini, MD, of the University of Genova (Italy), who served as discussant for the two studies. The IMpassion031 study raises the question of where we are in the use of immuno-oncology for eTNBC. The study is now one of five neoadjuvant trials in this population.
Dr. Lambertini cited the KEYNOTE-522 study, which showed significant results in EFS. However, sample sizes and statistical design were different between these studies. “I think we need large studies of data in the adjuvant and postneoadjuvant setting for patients with triple-negative breast cancer.”
Postneoadjuvant considerations from the IMpassion031 trial showed good outcomes with no additional benefit of an immune checkpoint inhibitors.
For those patients with a pCR, it is definitely time to de-escalate treatment,” he said. In patients without pCR, escalation is needed, but an improved definition of pCR is also needed.
With regard to the ATHENE study, “it may be considered a positive study because the threshold of 40% was reached,” he said. The question is what is the optimum chemotherapy backbone. There appears to be no added benefit to adding an immune checkpoint inhibitor.
There are needs for defining the role of immunotherapy in HER2-positive breast cancer and more biomarker research to inform patient selection and study design, he said.
Finally, “I am not sure that the addition of an immune checkpoint inhibitor can be considered a de-escalation,” he noted.
IMpassion031 was supported by F. Hoffmann–La Roche. Dr. Barrio disclosed financial relationships with numerous companies. ABSCG-52/ATHENE was supported by the Austrian Breast and Colorectal Cancer Study Group and Roche Austria. Dr. Rinnerthaler disclosed relationships with multiple companies including Amgen, Daiichi Sankyo, Lilly, Gilead, MSD, Novartis, Pfizer, Roche, Seagen, and Pierre Fabre. Dr. Lambertini disclosed relationships with multiple companies including Roche, Novartis, AstraZeneca, Lilly, Exact Sciences, Pfizer, MSD, Seagen, Gilead, Takeda, Sandoz, Ipsen, Libbs, Knight, and Daiichi Sankyo.
FROM ESMO BREAST CANCER 2023