Merck: Phase 3 KEYNOTE-811 trial met one of two endpoints

Merck announced that the Phase 3 KEYNOTE-811 trial investigating KEYTRUDA, Merck’s anti-PD-1 therapy, in combination with trastuzumab and chemotherapy met one of its dual primary endpoints of progression-free survival for the first-line treatment of human epidermal growth factor receptor 2-positive advanced gastric or gastroesophageal junction adenocarcinoma. At a pre-specified interim analysis conducted by an independent Data Monitoring Committee, KEYTRUDA in combination with trastuzumab and chemotherapy demonstrated a statistically significant improvement in PFS compared to placebo in combination with trastuzumab and chemotherapy in the intention-to-treat study population. Based on a pre-specified subgroup analysis by PD-L1 expression, the improvement in PFS observed in the ITT population was limited to patients whose tumors were PD-L1 positive. In the study, more than 80% of patients had tumors that were PD-L1 positive. Merck has discussed these findings with the U.S. FDA and is working with the FDA to update the current indication for KEYTRUDA in HER2-positive gastric or GEJ adenocarcinoma to those patients whose tumors are PD-L1 positive. In addition, these results will be presented at an upcoming medical meeting and shared with regulatory authorities worldwide.