46 Neoadjuvant Pembrolizumab or Placebo Plus Chemotherapy Followed by Adjuvant Pembrolizumab or Placebo for High-Risk, Early-Stage Triple-Negative Breast Cancer: Overall Survival and Subgroup Results From the Phase 3 KEYNOTE-522 Study

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Article
Miami Breast Cancer Conference® Abstracts Supplement42nd Annual Miami Breast Cancer Conference® - Abstracts
Volume 39
Issue 4
Pages: 26-27

46 Neoadjuvant Pembrolizumab or Placebo Plus Chemotherapy Followed by Adjuvant Pembrolizumab or Placebo for High-Risk, Early-Stage Triple-Negative Breast Cancer: Overall Survival and Subgroup Results From the Phase 3 KEYNOTE-522 Study

46 Neoadjuvant Pembrolizumab or Placebo Plus Chemotherapy Followed by Adjuvant Pembrolizumab or Placebo for High-Risk, Early-Stage Triple-Negative Breast Cancer: Overall Survival and Subgroup Results From the Phase 3 KEYNOTE-522 Study

Background

In the phase 3 KEYNOTE-522 (NCT03036488), neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab significantly improved pathological complete response and event-free survival (primary end points) vs neoadjuvant placebo plus chemotherapy followed by adjuvant placebo in patients with high-risk, early-stage triple-negative breast cancer (TNBC). At the prespecified analysis of overall survival (OS; secondary end point; data cutoff, March 22, 2024), the HR favored pembrolizumab (0.66; 95% CI, 0.50-0.87; P = .0015, crossing the prespecified significance boundary of 0.00503). We present OS results in prespecified subgroups based on residual cancer burden (RCB) and post hoc OS analyses in patients with baseline T2N0 disease.

Materials and Methods

Eligible patients with previously untreated, nonmetastatic, centrally confirmed TNBC (stage T1c N1-2 or T2-4 N0-2 per AJCC) were randomized 2:1 to neoadjuvant pembrolizumab at 200 mg every 3 weeks or placebo plus 4 cycles of paclitaxel plus carboplatin, followed by 4 cycles of doxorubicin or epirubicin plus cyclophosphamide. After definitive surgery, patients received adjuvant pembrolizumab or placebo for 9 cycles or until recurrence or unacceptable toxicity. The Kaplan-Meier method was used to estimate the subgroups for OS. HRs (95% CIs) for OS subgroups were based on the Cox regression model with the Efron method of tie handling with treatment as a covariate. RCB was assessed by the local pathologist at the time of definitive surgery.

Results

1174 patients were randomized to pembro (n = 784) or placebo (n = 390). At the data cutoff for OS (March 22, 2024), median follow-up was 75.1 months (range, 65.9-84.0). Data are shown in the Table. RCB rates were 63.5% with pembrolizumab vs 56.2% with placebo for RCB-0, 8.8% vs 11.5% for RCB-1, 18.4% vs 20.3% for RCB-2, and 5.1% vs 6.7% for RCB-3. At 5 years, OS rates (95% CIs) in patients with baseline T2N0 disease were 93.3% (89.9%-95.6%) with pembrolizumab vs 89.2% (83.2%-93.1%) with placebo. OS in subgroups based on PD-L1 expression will also be presented.

Conclusion

In patients with high-risk, early-stage TNBC, neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab showed clinically meaningful improvements in OS vs neoadjuvant chemotherapy alone, with the highest OS benefit observed in patients with the least RCB.

Articles in this issue

12 Gut Microbiome Composition and Pathological Complete Response After Chemotherapy in Breast Cancer: Insights From a Pilot Study
12 Gut Microbiome Composition and Pathological Complete Response After Chemotherapy in Breast Cancer: Insights From a Pilot Study
13 Preliminary Analysis of Change During Treatment of Financial Toxicity and Quality of Life in Breast Cancer Patients
13 Preliminary Analysis of Change During Treatment of Financial Toxicity and Quality of Life in Breast Cancer Patients
15 Utilizing Circulating Tumor Cells to Guide HER2-Directed Therapy in IHC/FISH-Negative HER2+ Metastatic Breast Cancer
15 Utilizing Circulating Tumor Cells to Guide HER2-Directed Therapy in IHC/FISH-Negative HER2+ Metastatic Breast Cancer
16 A Miami Hospital’s Infrastructure to Help Decrease Late-Stage Breast Cancer Diagnosis and Improve Health Equity
16 A Miami Hospital’s Infrastructure to Help Decrease Late-Stage Breast Cancer Diagnosis and Improve Health Equity
17 Salmonella and the Breast: A Literature Review of Salmonella-Induced Breast Abscesses
17 Salmonella and the Breast: A Literature Review of Salmonella-Induced Breast Abscesses
18 Tolerability of First-Line Treatment With Ribociclib for Metastatic Breast Cancer Using 2 Large US Data Sources
18 Tolerability of First-Line Treatment With Ribociclib for Metastatic Breast Cancer Using 2 Large US Data Sources
20 Impact of Ribociclib Dose Reduction on Efficacy in Patients With Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Early Breast
20 Impact of Ribociclib Dose Reduction on Efficacy in Patients With Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Early Breast
21 Distant Disease-Free Survival Across Key Subgroups From the Phase 3 NATALEE Trial of Ribociclib Plus a Nonsteroidal Aromatase Inhibitor in Patients With HR+/HER2− Early Breast Cancer
21 Distant Disease-Free Survival Across Key Subgroups From the Phase 3 NATALEE Trial of Ribociclib Plus a Nonsteroidal Aromatase Inhibitor in Patients With HR+/HER2− Early Breast Cancer
22 Efficacy and Safety of Ribociclib + Nonsteroidal Aromatase Inhibitor in Younger Patients With HR+/HER2− Early Breast Cancer in NATALEE
22 Efficacy and Safety of Ribociclib + Nonsteroidal Aromatase Inhibitor in Younger Patients With HR+/HER2− Early Breast Cancer in NATALEE
23 Clinical Outcomes in Patients With HR+/HER2− Early Breast Cancer By Prior Systemic Treatment: A Subgroup Analysis of the NATALEE Trial
23 Clinical Outcomes in Patients With HR+/HER2− Early Breast Cancer By Prior Systemic Treatment: A Subgroup Analysis of the NATALEE Trial
TPS 24 Phase Ib Dose-Finding Study of [177Lu]Lu-NeoB + Ribociclib + Fulvestrant in Patients With ER+/HER2− Advanced Breast Cancer With GRPR Expression With Early Relapse FromAdjuvant Endocrine Therapy or Progression on ET + CDK4/6i for ABC
TPS 24 Phase Ib Dose-Finding Study of [177Lu]Lu-NeoB + Ribociclib + Fulvestrant in Patients With ER+/HER2− Advanced Breast Cancer With GRPR Expression With Early Relapse FromAdjuvant Endocrine Therapy or Progression on ET + CDK4/6i for ABC
TPS 25 Phase 1/2 Study of the Novel Radioligand Therapy [177Lu]Lu-NeoB Plus Capecitabine in Patients With ER+/HER2− Advanced Breast Cancer (ABC) With GRPR Expression After Progression on Prior Endocrine Therapy Plus a CDK4/6 Inhibitor for ABC
TPS 25 Phase 1/2 Study of the Novel Radioligand Therapy [177Lu]Lu-NeoB Plus Capecitabine in Patients With ER+/HER2− Advanced Breast Cancer (ABC) With GRPR Expression After Progression on Prior Endocrine Therapy Plus a CDK4/6 Inhibitor for ABC
26 Risk of Recurrence in Real-World NATALEE- and monarchE-Eligible Populations of Patients With HR+/HER2− Early Breast Cancer in an Electronic Health Record-Derived Database
26 Risk of Recurrence in Real-World NATALEE- and monarchE-Eligible Populations of Patients With HR+/HER2− Early Breast Cancer in an Electronic Health Record-Derived Database
27 Elacestrant vs Standard of Care in ER+, HER2- Advanced or Metastatic Breast Cancer With ESR1-Mutated Tumors: ESR1 Allelic Frequencies and Clinical Activity From the Phase 3 EMERALD Trial
27 Elacestrant vs Standard of Care in ER+, HER2- Advanced or Metastatic Breast Cancer With ESR1-Mutated Tumors: ESR1 Allelic Frequencies and Clinical Activity From the Phase 3 EMERALD Trial
TPS 28 ELEGANT: Elacestrant VS Standard Endocrine Therapy in Women and Men With Node-Positive, Estrogen Receptor-Positive, HER2-Negative, Early Breast Cancer With High Risk of Recurrence in a Global, Multicenter, Randomized, Open-Label Phase 3 Study
TPS 28 ELEGANT: Elacestrant VS Standard Endocrine Therapy in Women and Men With Node-Positive, Estrogen Receptor-Positive, HER2-Negative, Early Breast Cancer With High Risk of Recurrence in a Global, Multicenter, Randomized, Open-Label Phase 3 Study
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