More Support for Adding Pembrolizumab to Chemotherapy and Surgery in Triple-Negative Breast Cancer

The KEYNOTE-522 regimen of adding pembrolizumab to chemotherapy and surgery has been widely adopted by clinicians for treatment of stage II/III triple-negative breast cancer based on the previously reported, clinically and statistically significant improvements in pathologic complete response and event-free survival (NEJM JW Oncol Hematol Feb 11 2022 and N Engl J Med 2022 Feb 10; 386:556). Now, after a median follow-up of 75 months, researchers report findings for overall survival, a secondary endpoint.

In the industry-supported, phase 3 KEYNOTE-522 trial, nearly 1200 patients with previously untreated stage II or III triple-negative breast cancer were randomized to receive neoadjuvant pembrolizumab or placebo plus chemotherapy (paclitaxel plus carboplatin, then either doxorubicin or epirubicin plus cyclophosphamide), followed by definitive surgery and then adjuvant pembrolizumab or placebo.

Estimated overall survival at 60 months was significantly higher in the pembrolizumab group than the placebo group (87% vs. 82%). Adverse events were consistent with those previously reported. As expected, immune-mediated adverse events occurred more often in the pembrolizumab group than in the placebo group (35% vs. 13%).