Final overall survival results of the multinational phase 3 KEYNOTE-522 trial: pembrolizumab plus chemotherapy for early-stage TNBC

The first interim analysis of the multinational phase 3 KEYNOTE-522 trial showed significant improvements in pathological complete response and event-free survival with the addition of pembrolizumab to first-line platinum-containing chemotherapy for early-stage triple-negative breast cancer at median 15.1 months of follow-up. Final overall survival results of the trial have now been published. Patients were randomized 2:1 to neoadjuvant pembrolizumab or placebo plus chemotherapy followed by definitive surgery and adjuvant pembrolizumab or placebo. With median follow-up of 75.1 months, the estimated overall survival rate at 60 months was 86.6% (95% CI 84.0-88.8) in the pembrolizumab-chemotherapy group, as compared with 81.7% (77.5-85.2) in the placebo-chemotherapy group (p=0.002). Adverse events were consistent with the established safety profiles of pembrolizumab and chemotherapy. The authors conclude that neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab, as compared with neoadjuvant chemotherapy alone, resulted in a significant improvement is overall survival among patients with previously untreated, early-stage, triple-negative breast cancer.