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Study Overview
Objective. To evaluate the efficacy and safety of pembrolizumab in combination with neoadjuvant chemotherapy followed by adjuvant pembrolizumab in early-stage triple-negative breast cancer.
Design. International, multicenter, randomized, double-blind, phase 3 trial.
Intervention. Patients were randomly assigned in a 2:1 fashion to receive either pembrolizumab or placebo. Patients received 4 cycles of neoadjuvant pembrolizumab or placebo once every 3 weeks, in addition to weekly paclitaxel 80 mg/m2 plus carboplatin AUC5 once every 3 weeks. This was followed by 4 cycles of pembrolizumab or placebo plus doxorubicin 60 mg/m2 or epirubicin 90 mg/m2 plus cyclophosphamide 600 mg/m2 once every 3 weeks. Patients then underwent definitive surgery 3 to 6 weeks after completion of neoadjuvant therapy. In the adjuvant setting, patients received pembrolizumab or placebo once every 3 weeks for up to 9 cycles. Adjuvant capecitabine was not allowed.
Setting and participants. A total of 1174 patients underwent randomization: 784 patients in the pembrolizumab/chemotherapy group and 390 patients in the placebo/chemotherapy group. Eligible patients had newly diagnosed, centrally confirmed triple-negative breast cancer (nonmetastatic: T1c, N1-2 or T2-4, N0-2). Patients were eligible regardless of PD-L1 status, and those with inflammatory breast cancer and multifocal primaries were eligible.
Main outcome measures. The primary endpoints of this study were pathologic complete response (pCR) rate (defined as ypT0/ypTis, ypN0) at the time of surgery and event-free survival (EFS) in the intention-to-treat population. Secondary endpoints included pCR in all patients, pCR among patients with PD-L1–positive tumors, EFS among patients with PD-L1–positive tumors, and overall survival among all patients and those with PD-L1–positive tumors. PD-L1 expression was assessed using the PD-L1 IHC 22C3 pharmDx assay (Agilent, Santa Clara, CA). Expression was characterized according to the combined positive score, with a score of 1% or greater being considered positive.
Results. The baseline characteristics were well balanced between the treatment arms. At the time of the second interim analysis, the median duration of follow-up was 15.5 months. The pCR rate among the first 602 patients who were randomized was 64.8% in the pembrolizumab/chemotherapy group and 51.2% in the placebo group (P < 0.001; 95% confidence interval, 5.4-21.8). The pCR rate in the PD-L1–positive population was 68.9% in the pembrolizumab/chemotherapy group, as compared to 54.9% in the placebo group. In the PD-L1–negative population, the pCR rate was 45.3% in the pembrolizumab/chemotherapy group, as compared to 30.3% in the placebo group. At the time of analysis, 104 events had occurred, and the estimated percentage of patients at 18 months who were alive without disease progression was 91% in the pembrolizumab group and 85% in the placebo group. The median was not reached in either group.
Grade 3 or higher adverse events in the neoadjuvant phase were seen in 76.8% and 72.2% of patients in the pembrolizumab and placebo arms, respectively. Serious treatment-related adverse events occurred in 32% of patients in the pembrolizumab group compared to 19% in the placebo group. Febrile neutropenia and anemia were the most common. Discontinuation of the trial drug due to adverse events occurred in 23% of patients in the pembrolizumab arm and in 12% in the placebo arm. The majority of treatment-related adverse events occurred in the neoadjuvant phase. In the adjuvant phase, treatment-related adverse events occurred in 48% and 43% of patients in the pembrolizumab and placebo groups, respectively.
Conclusion. The combination of neoadjuvant chemotherapy and pembrolizumab in patients with newly diagnosed, early-stage, triple-negative breast cancer yielded a higher percentage of patients achieving a pCR as compared with chemotherapy plus placebo.
Commentary
The current study adds to the growing body of literature outlining the efficacy of immune checkpoint inhibition in triple-negative breast cancer. The previously published IMpassion130 trial showed that the addition of the PD-L1 antibody atezolizumab to nab-paclitaxel improved progression-free survival in patients with PD-L1–positive (1% or greater), metastatic triple-negative breast cancer.1 Similarly, in the phase 2 I-SPY2 trial, the addition of pembrolizumab to standard neoadjuvant chemotherapy led to a near tripling of the pCR rates in triple-negative breast cancer.2 While the current study demonstrated improved pCR rates with pembrolizumab, no difference in EFS has yet been demonstrated; however, longer-term follow-up will be required. There certainly are numerous studies documenting an association between pCR and improved disease-free survival and possibly overall survival. Cortazar and colleagues performed a pooled analysis of 12 international trials, which demonstrated an association between pCR and improved EFS (hazard ratio [HR], 0.24) and overall survival (HR, 0.16) in patients with triple-negative breast cancer.3 The results of the current study will require longer-term follow-up to confirm such an association.
The current study appears to have demonstrated a benefit with the addition of pembrolizumab across treatment subgroups, particularly in the PD-L1–positive and PD-L1–negative populations. While this differs from the findings of the IMpassion130 trial, it is quite difficult to draw definitive conclusions because the 2 trials studied different antibodies, and thus used a different assay to define PD-L1 positivity. Notable differences exist in determination of PD-L1 status across assays, and it is important for providers to use the appropriate assay for each antibody. These differences highlight the need for more informative biomarkers to predict a benefit from immune checkpoint inhibition.
It is also noteworthy that the control arm in the current trial was a platinum-based regimen. Platinum-based neoadjuvant regimens previously have been shown to induce higher pCR rates in triple-negative breast cancer; however, the incorporation of carboplatin as standard of care remains a topic of debate.4 Nevertheless, a similar trial evaluating the efficacy of atezolizumab combined with platinum-based neoadjuvant chemotherapy in triple-negative breast cancer, NSABP B-59 (NCT03281954), is underway, with the control arm also incorporating carboplatin. The results of this study will also help validate the role of checkpoint inhibitors in the neoadjuvant setting in triple-negative breast cancer. Of note, this trial did not allow for the use of adjuvant capecitabine, which has been previously shown in the CREATE-X trial to prolong survival in this population.5 How the use of adjuvant capecitabine would impact these results is completely unknown.6 The incidence of grade 3 or higher toxicities in the current trial appeared to be similar in both groups. There did appear to be a higher incidence of infusion reactions and skin reactions in the pembrolizumab groups. Immune-related adverse events were consistent with prior pembrolizumab data.
Applications for Clinical Practice
KEYNOTE-522 adds to the growing evidence suggesting that incorporation of immune checkpoint inhibitors into neoadjuvant therapy in patients with triple-negative breast cancer can improve pCR rates; however, its use as a standard of care will require longer-term follow-up to ensure the noted findings translate into improvement in EFS and, ultimately, overall survival.
– Daniel Isaac, DO, MS
1. Schmid P, Adams S, Rugo HS, et al. Atezolizumab and nab-paclitaxel in advanced triple-negative breast cancer. N Engl J Med. 2018;379:2108-2121.
2. Nanda R, Liu MC, Yau C, et al. Pembrolizumab plus standard neoadjuvant therapy for high-risk breast cancer (BC): results from I-SPY 2. J Clin Oncol. 2017;35: Suppl:506. Abstract 506.
3. Cortazar P, Zhang L, Untch M, et al. Pathological complete response and long-term clinical benefit in breast cancer: the CTNeoBC pooled analysis. Lancet. 2014;384:164-172.
4. Sikov WM, Berry DA, Perou CM, et al. Impact of the addition of carboplatin and/or bevacizumab to neoadjuvant one-per-week paclitaxel followed by dose-dense doxorubicin and cyclophosphamide on pathologic complete response in stage II to III triple-negative breast cancer: CALGB 40603 (Alliance). J Clin Oncol. 2015;33:13-21.
5. Masuda N, Lee S-J, Ohtani S, et al. Adjuvant capecitabine for breast cancer after preoperative chemotherapy. N Engl J Med. 2017;376:2147-2159.
6. von Minckwitz G, Schneeweiss A, Loibl S, et al. Neoadjuvant carboplatin in patients with triple-negative and HER2-positive early breast cancer (GeparSixto; GBG 66): a randomised phase 2 trial. Lancet Oncol. 2014;15:747-756.
Study Overview
Objective. To evaluate the efficacy and safety of pembrolizumab in combination with neoadjuvant chemotherapy followed by adjuvant pembrolizumab in early-stage triple-negative breast cancer.
Design. International, multicenter, randomized, double-blind, phase 3 trial.
Intervention. Patients were randomly assigned in a 2:1 fashion to receive either pembrolizumab or placebo. Patients received 4 cycles of neoadjuvant pembrolizumab or placebo once every 3 weeks, in addition to weekly paclitaxel 80 mg/m2 plus carboplatin AUC5 once every 3 weeks. This was followed by 4 cycles of pembrolizumab or placebo plus doxorubicin 60 mg/m2 or epirubicin 90 mg/m2 plus cyclophosphamide 600 mg/m2 once every 3 weeks. Patients then underwent definitive surgery 3 to 6 weeks after completion of neoadjuvant therapy. In the adjuvant setting, patients received pembrolizumab or placebo once every 3 weeks for up to 9 cycles. Adjuvant capecitabine was not allowed.
Setting and participants. A total of 1174 patients underwent randomization: 784 patients in the pembrolizumab/chemotherapy group and 390 patients in the placebo/chemotherapy group. Eligible patients had newly diagnosed, centrally confirmed triple-negative breast cancer (nonmetastatic: T1c, N1-2 or T2-4, N0-2). Patients were eligible regardless of PD-L1 status, and those with inflammatory breast cancer and multifocal primaries were eligible.
Main outcome measures. The primary endpoints of this study were pathologic complete response (pCR) rate (defined as ypT0/ypTis, ypN0) at the time of surgery and event-free survival (EFS) in the intention-to-treat population. Secondary endpoints included pCR in all patients, pCR among patients with PD-L1–positive tumors, EFS among patients with PD-L1–positive tumors, and overall survival among all patients and those with PD-L1–positive tumors. PD-L1 expression was assessed using the PD-L1 IHC 22C3 pharmDx assay (Agilent, Santa Clara, CA). Expression was characterized according to the combined positive score, with a score of 1% or greater being considered positive.
Results. The baseline characteristics were well balanced between the treatment arms. At the time of the second interim analysis, the median duration of follow-up was 15.5 months. The pCR rate among the first 602 patients who were randomized was 64.8% in the pembrolizumab/chemotherapy group and 51.2% in the placebo group (P < 0.001; 95% confidence interval, 5.4-21.8). The pCR rate in the PD-L1–positive population was 68.9% in the pembrolizumab/chemotherapy group, as compared to 54.9% in the placebo group. In the PD-L1–negative population, the pCR rate was 45.3% in the pembrolizumab/chemotherapy group, as compared to 30.3% in the placebo group. At the time of analysis, 104 events had occurred, and the estimated percentage of patients at 18 months who were alive without disease progression was 91% in the pembrolizumab group and 85% in the placebo group. The median was not reached in either group.
Grade 3 or higher adverse events in the neoadjuvant phase were seen in 76.8% and 72.2% of patients in the pembrolizumab and placebo arms, respectively. Serious treatment-related adverse events occurred in 32% of patients in the pembrolizumab group compared to 19% in the placebo group. Febrile neutropenia and anemia were the most common. Discontinuation of the trial drug due to adverse events occurred in 23% of patients in the pembrolizumab arm and in 12% in the placebo arm. The majority of treatment-related adverse events occurred in the neoadjuvant phase. In the adjuvant phase, treatment-related adverse events occurred in 48% and 43% of patients in the pembrolizumab and placebo groups, respectively.
Conclusion. The combination of neoadjuvant chemotherapy and pembrolizumab in patients with newly diagnosed, early-stage, triple-negative breast cancer yielded a higher percentage of patients achieving a pCR as compared with chemotherapy plus placebo.
Commentary
The current study adds to the growing body of literature outlining the efficacy of immune checkpoint inhibition in triple-negative breast cancer. The previously published IMpassion130 trial showed that the addition of the PD-L1 antibody atezolizumab to nab-paclitaxel improved progression-free survival in patients with PD-L1–positive (1% or greater), metastatic triple-negative breast cancer.1 Similarly, in the phase 2 I-SPY2 trial, the addition of pembrolizumab to standard neoadjuvant chemotherapy led to a near tripling of the pCR rates in triple-negative breast cancer.2 While the current study demonstrated improved pCR rates with pembrolizumab, no difference in EFS has yet been demonstrated; however, longer-term follow-up will be required. There certainly are numerous studies documenting an association between pCR and improved disease-free survival and possibly overall survival. Cortazar and colleagues performed a pooled analysis of 12 international trials, which demonstrated an association between pCR and improved EFS (hazard ratio [HR], 0.24) and overall survival (HR, 0.16) in patients with triple-negative breast cancer.3 The results of the current study will require longer-term follow-up to confirm such an association.
The current study appears to have demonstrated a benefit with the addition of pembrolizumab across treatment subgroups, particularly in the PD-L1–positive and PD-L1–negative populations. While this differs from the findings of the IMpassion130 trial, it is quite difficult to draw definitive conclusions because the 2 trials studied different antibodies, and thus used a different assay to define PD-L1 positivity. Notable differences exist in determination of PD-L1 status across assays, and it is important for providers to use the appropriate assay for each antibody. These differences highlight the need for more informative biomarkers to predict a benefit from immune checkpoint inhibition.
It is also noteworthy that the control arm in the current trial was a platinum-based regimen. Platinum-based neoadjuvant regimens previously have been shown to induce higher pCR rates in triple-negative breast cancer; however, the incorporation of carboplatin as standard of care remains a topic of debate.4 Nevertheless, a similar trial evaluating the efficacy of atezolizumab combined with platinum-based neoadjuvant chemotherapy in triple-negative breast cancer, NSABP B-59 (NCT03281954), is underway, with the control arm also incorporating carboplatin. The results of this study will also help validate the role of checkpoint inhibitors in the neoadjuvant setting in triple-negative breast cancer. Of note, this trial did not allow for the use of adjuvant capecitabine, which has been previously shown in the CREATE-X trial to prolong survival in this population.5 How the use of adjuvant capecitabine would impact these results is completely unknown.6 The incidence of grade 3 or higher toxicities in the current trial appeared to be similar in both groups. There did appear to be a higher incidence of infusion reactions and skin reactions in the pembrolizumab groups. Immune-related adverse events were consistent with prior pembrolizumab data.
Applications for Clinical Practice
KEYNOTE-522 adds to the growing evidence suggesting that incorporation of immune checkpoint inhibitors into neoadjuvant therapy in patients with triple-negative breast cancer can improve pCR rates; however, its use as a standard of care will require longer-term follow-up to ensure the noted findings translate into improvement in EFS and, ultimately, overall survival.
– Daniel Isaac, DO, MS
Study Overview
Objective. To evaluate the efficacy and safety of pembrolizumab in combination with neoadjuvant chemotherapy followed by adjuvant pembrolizumab in early-stage triple-negative breast cancer.
Design. International, multicenter, randomized, double-blind, phase 3 trial.
Intervention. Patients were randomly assigned in a 2:1 fashion to receive either pembrolizumab or placebo. Patients received 4 cycles of neoadjuvant pembrolizumab or placebo once every 3 weeks, in addition to weekly paclitaxel 80 mg/m2 plus carboplatin AUC5 once every 3 weeks. This was followed by 4 cycles of pembrolizumab or placebo plus doxorubicin 60 mg/m2 or epirubicin 90 mg/m2 plus cyclophosphamide 600 mg/m2 once every 3 weeks. Patients then underwent definitive surgery 3 to 6 weeks after completion of neoadjuvant therapy. In the adjuvant setting, patients received pembrolizumab or placebo once every 3 weeks for up to 9 cycles. Adjuvant capecitabine was not allowed.
Setting and participants. A total of 1174 patients underwent randomization: 784 patients in the pembrolizumab/chemotherapy group and 390 patients in the placebo/chemotherapy group. Eligible patients had newly diagnosed, centrally confirmed triple-negative breast cancer (nonmetastatic: T1c, N1-2 or T2-4, N0-2). Patients were eligible regardless of PD-L1 status, and those with inflammatory breast cancer and multifocal primaries were eligible.
Main outcome measures. The primary endpoints of this study were pathologic complete response (pCR) rate (defined as ypT0/ypTis, ypN0) at the time of surgery and event-free survival (EFS) in the intention-to-treat population. Secondary endpoints included pCR in all patients, pCR among patients with PD-L1–positive tumors, EFS among patients with PD-L1–positive tumors, and overall survival among all patients and those with PD-L1–positive tumors. PD-L1 expression was assessed using the PD-L1 IHC 22C3 pharmDx assay (Agilent, Santa Clara, CA). Expression was characterized according to the combined positive score, with a score of 1% or greater being considered positive.
Results. The baseline characteristics were well balanced between the treatment arms. At the time of the second interim analysis, the median duration of follow-up was 15.5 months. The pCR rate among the first 602 patients who were randomized was 64.8% in the pembrolizumab/chemotherapy group and 51.2% in the placebo group (P < 0.001; 95% confidence interval, 5.4-21.8). The pCR rate in the PD-L1–positive population was 68.9% in the pembrolizumab/chemotherapy group, as compared to 54.9% in the placebo group. In the PD-L1–negative population, the pCR rate was 45.3% in the pembrolizumab/chemotherapy group, as compared to 30.3% in the placebo group. At the time of analysis, 104 events had occurred, and the estimated percentage of patients at 18 months who were alive without disease progression was 91% in the pembrolizumab group and 85% in the placebo group. The median was not reached in either group.
Grade 3 or higher adverse events in the neoadjuvant phase were seen in 76.8% and 72.2% of patients in the pembrolizumab and placebo arms, respectively. Serious treatment-related adverse events occurred in 32% of patients in the pembrolizumab group compared to 19% in the placebo group. Febrile neutropenia and anemia were the most common. Discontinuation of the trial drug due to adverse events occurred in 23% of patients in the pembrolizumab arm and in 12% in the placebo arm. The majority of treatment-related adverse events occurred in the neoadjuvant phase. In the adjuvant phase, treatment-related adverse events occurred in 48% and 43% of patients in the pembrolizumab and placebo groups, respectively.
Conclusion. The combination of neoadjuvant chemotherapy and pembrolizumab in patients with newly diagnosed, early-stage, triple-negative breast cancer yielded a higher percentage of patients achieving a pCR as compared with chemotherapy plus placebo.
Commentary
The current study adds to the growing body of literature outlining the efficacy of immune checkpoint inhibition in triple-negative breast cancer. The previously published IMpassion130 trial showed that the addition of the PD-L1 antibody atezolizumab to nab-paclitaxel improved progression-free survival in patients with PD-L1–positive (1% or greater), metastatic triple-negative breast cancer.1 Similarly, in the phase 2 I-SPY2 trial, the addition of pembrolizumab to standard neoadjuvant chemotherapy led to a near tripling of the pCR rates in triple-negative breast cancer.2 While the current study demonstrated improved pCR rates with pembrolizumab, no difference in EFS has yet been demonstrated; however, longer-term follow-up will be required. There certainly are numerous studies documenting an association between pCR and improved disease-free survival and possibly overall survival. Cortazar and colleagues performed a pooled analysis of 12 international trials, which demonstrated an association between pCR and improved EFS (hazard ratio [HR], 0.24) and overall survival (HR, 0.16) in patients with triple-negative breast cancer.3 The results of the current study will require longer-term follow-up to confirm such an association.
The current study appears to have demonstrated a benefit with the addition of pembrolizumab across treatment subgroups, particularly in the PD-L1–positive and PD-L1–negative populations. While this differs from the findings of the IMpassion130 trial, it is quite difficult to draw definitive conclusions because the 2 trials studied different antibodies, and thus used a different assay to define PD-L1 positivity. Notable differences exist in determination of PD-L1 status across assays, and it is important for providers to use the appropriate assay for each antibody. These differences highlight the need for more informative biomarkers to predict a benefit from immune checkpoint inhibition.
It is also noteworthy that the control arm in the current trial was a platinum-based regimen. Platinum-based neoadjuvant regimens previously have been shown to induce higher pCR rates in triple-negative breast cancer; however, the incorporation of carboplatin as standard of care remains a topic of debate.4 Nevertheless, a similar trial evaluating the efficacy of atezolizumab combined with platinum-based neoadjuvant chemotherapy in triple-negative breast cancer, NSABP B-59 (NCT03281954), is underway, with the control arm also incorporating carboplatin. The results of this study will also help validate the role of checkpoint inhibitors in the neoadjuvant setting in triple-negative breast cancer. Of note, this trial did not allow for the use of adjuvant capecitabine, which has been previously shown in the CREATE-X trial to prolong survival in this population.5 How the use of adjuvant capecitabine would impact these results is completely unknown.6 The incidence of grade 3 or higher toxicities in the current trial appeared to be similar in both groups. There did appear to be a higher incidence of infusion reactions and skin reactions in the pembrolizumab groups. Immune-related adverse events were consistent with prior pembrolizumab data.
Applications for Clinical Practice
KEYNOTE-522 adds to the growing evidence suggesting that incorporation of immune checkpoint inhibitors into neoadjuvant therapy in patients with triple-negative breast cancer can improve pCR rates; however, its use as a standard of care will require longer-term follow-up to ensure the noted findings translate into improvement in EFS and, ultimately, overall survival.
– Daniel Isaac, DO, MS
1. Schmid P, Adams S, Rugo HS, et al. Atezolizumab and nab-paclitaxel in advanced triple-negative breast cancer. N Engl J Med. 2018;379:2108-2121.
2. Nanda R, Liu MC, Yau C, et al. Pembrolizumab plus standard neoadjuvant therapy for high-risk breast cancer (BC): results from I-SPY 2. J Clin Oncol. 2017;35: Suppl:506. Abstract 506.
3. Cortazar P, Zhang L, Untch M, et al. Pathological complete response and long-term clinical benefit in breast cancer: the CTNeoBC pooled analysis. Lancet. 2014;384:164-172.
4. Sikov WM, Berry DA, Perou CM, et al. Impact of the addition of carboplatin and/or bevacizumab to neoadjuvant one-per-week paclitaxel followed by dose-dense doxorubicin and cyclophosphamide on pathologic complete response in stage II to III triple-negative breast cancer: CALGB 40603 (Alliance). J Clin Oncol. 2015;33:13-21.
5. Masuda N, Lee S-J, Ohtani S, et al. Adjuvant capecitabine for breast cancer after preoperative chemotherapy. N Engl J Med. 2017;376:2147-2159.
6. von Minckwitz G, Schneeweiss A, Loibl S, et al. Neoadjuvant carboplatin in patients with triple-negative and HER2-positive early breast cancer (GeparSixto; GBG 66): a randomised phase 2 trial. Lancet Oncol. 2014;15:747-756.
1. Schmid P, Adams S, Rugo HS, et al. Atezolizumab and nab-paclitaxel in advanced triple-negative breast cancer. N Engl J Med. 2018;379:2108-2121.
2. Nanda R, Liu MC, Yau C, et al. Pembrolizumab plus standard neoadjuvant therapy for high-risk breast cancer (BC): results from I-SPY 2. J Clin Oncol. 2017;35: Suppl:506. Abstract 506.
3. Cortazar P, Zhang L, Untch M, et al. Pathological complete response and long-term clinical benefit in breast cancer: the CTNeoBC pooled analysis. Lancet. 2014;384:164-172.
4. Sikov WM, Berry DA, Perou CM, et al. Impact of the addition of carboplatin and/or bevacizumab to neoadjuvant one-per-week paclitaxel followed by dose-dense doxorubicin and cyclophosphamide on pathologic complete response in stage II to III triple-negative breast cancer: CALGB 40603 (Alliance). J Clin Oncol. 2015;33:13-21.
5. Masuda N, Lee S-J, Ohtani S, et al. Adjuvant capecitabine for breast cancer after preoperative chemotherapy. N Engl J Med. 2017;376:2147-2159.
6. von Minckwitz G, Schneeweiss A, Loibl S, et al. Neoadjuvant carboplatin in patients with triple-negative and HER2-positive early breast cancer (GeparSixto; GBG 66): a randomised phase 2 trial. Lancet Oncol. 2014;15:747-756.