Phase III KEYNOTE-756 trial of Keytruda + chemotherapy as neoadjuvant meets primary endpoint in breast cancer ER+/HER2-.- Merck Inc

At a prespecified interim analysis conducted by an independent Data Monitoring Committee (DMC), the Keytruda-based regimen demonstrated a statistically significant improvement in pCR rate compared to neoadjuvant placebo plus chemotherapy. A pCR is defined as a lack of all signs of cancer in tissue samples analyzed following completion of neoadjuvant therapy and definitive surgery. Based on the recommendation of the DMC, the trial will continue without changes to evaluate the other dual primary endpoint of event-free survival (EFS), per the trial design. The safety profile of Keytruda in this trial was consistent with that observed in previously reported studies; no new safety signals were identified. Results will be presented at an upcoming medical meeting.

KEYNOTE-756 is a randomized, double-blind Phase III trial (ClinicalTrials.gov, NCT03725059) evaluating Keytruda in combination with chemotherapy as neoadjuvant treatment, followed by adjuvant treatment with Keytruda plus endocrine therapy for the treatment of high-risk, early-stage ER+/HER2- breast cancer. The dual primary endpoints are pCR rate and EFS, and secondary endpoints include overall survival and safety. The trial enrolled 1,240 patients who were randomized 1:1 to receive: Keytruda (200 mg every three weeks [Q3W]) plus chemotherapy (paclitaxel weekly) for four cycles, followed by four additional cycles of Keytruda in combination with chemotherapy (doxorubicin or epirubicin plus cyclophosphamide) as neoadjuvant therapy prior to surgery, followed by nine cycles of Keytruda (Q3W) plus endocrine therapy (for up to 10 years) as adjuvant therapy post-surgery; or, Placebo (Q3W) plus chemotherapy (paclitaxel weekly) for four cycles, followed by four additional cycles of placebo in combination with chemotherapy (doxorubicin or epirubicin plus cyclophosphamide) as neoadjuvant therapy prior to surgery, followed by nine cycles of placebo (Q3W) plus endocrine therapy (for up to 10 years) as adjuvant therapy post-surgery.