Merck Inc. announces phase III KEYNOTE-522 trial met dual primary endpoint of event-free survival (EFS) in patients with high-risk early-stage triple-negative breast cancer.

Merck Inc. announced positive results from the pivotal neoadjuvant/adjuvant Phase III KEYNOTE-522 trial investigating Keytruda, Merck’s anti-PD-1 therapy, in combination with chemotherapy as pre-operative (neoadjuvant) treatment and then continuing as a single agent (adjuvant) treatment after surgery. KEYNOTE-522 met its dual primary endpoint of event-free survival (EFS) for the treatment of patients with high-risk early-stage triple-negative breast cancer (TNBC). Based on an interim analysis conducted by the independent Data Monitoring Committee (DMC), neoadjuvant Keytruda plus chemotherapy followed by adjuvant Keytruda as monotherapy showed a statistically significant and clinically meaningful improvement in EFS compared with neoadjuvant chemotherapy alone. As previously communicated, KEYNOTE-522 met its other dual primary endpoint of pathological complete response (pCR). The safety profile of Keytruda in this trial was consistent with that observed in previously reported studies; no new safety signals were identified. An analysis of pCR from KEYNOTE-522 was presented at the European Society for Medical Oncology (ESMO) 2019 Congress and published in the New England Journal of Medicine. Findings showed a statistically significant increase in pCR for Keytruda plus chemotherapy versus chemotherapy alone as neoadjuvant therapy in patients with early-stage TNBC, regardless of PD-L1 status. As previously announced, the company received a Complete Response Letter (CRL) from the FDA in March 2021 regarding Merck’s supplemental Biologics License Application (sBLA) seeking approval for Keytruda for the treatment of patients with high-risk early-stage TNBC based on these pCR data and early interim EFS findings. The CRL followed the FDA’s Oncologic Drugs Advisory Committee meeting that voted 10-0 that a regulatory decision should be deferred until further data were available from KEYNOTE-522. The Keytruda clinical development program for TNBC encompasses several internal studies and external collaborative trials, including the ongoing studies KEYNOTE-242 and KEYNOTE-355.