Keytruda Shows Positive Results in Early Stage, Triple-Negative Breast Cancer

Merck’s Keytruda (pembrolizumab) demonstrated positive event-free survival (EFS) in patients with high-risk, early stage triple-negative breast cancer in the pivotal neoadjuvant/adjuvant phase 3 study KEYNOTE-522, according to results presented at European Society for Medical Oncology (ESMO) Virtual Plenary.

This study compared Keytruda and chemotherapy given before surgery followed by Keytruda (the Keytruda regimen) compared with adjuvant chemotherapy followed by placebo after surgery (the chemotherapy-placebo regimen). After a median follow up of 39 months, the Keytruda regimen reduced the risk of event-free survival events by 37%. This is the first time an anti-PD-1/L1 therapy has demonstrated a statistically significant event-free survival result.

No new safety concerns were seen in this fourth interim analysis.

In May, Merck had announced that KEYNOTE-522 met the dual primary endpoint of pathological complete response at the first interim analysis. The trial is continuing to allow for additional follow-up of overall survival, a key secondary endpoint.

Keytruda is currently approved under accelerated approval in the United States in combination with chemotherapy for the treatment of patients with locally recurrent unresectable or metastatic TNBC whose tumors express PD-L1.

“These highly anticipated event-free survival results in this TNBC population build upon earlier findings from the KEYNOTE-522 trial and further support the potential use of Keytruda in these patients,” Vicki Goodman, M.D., vice president, clinical research, Merck Research Laboratories, said in a statement.