Merck announced positive topline results from the pivotal Phase 3 KEYNOTE-859 trial investigating KEYTRUDA, Merck's anti-PD-1 therapy, in combination with chemotherapy for the first-line treatment of patients with human epidermal growth factor receptor 2 (HER2)-negative locally advanced unresectable or metastatic gastric or GEJ adenocarcinoma. KEYTRUDA in combination with chemotherapy showed a statistically significant and clinically meaningful improvement in the trial's primary endpoint of overall survival (OS) versus chemotherapy alone in the all-randomized patient population at a pre-specified interim analysis conducted by an independent Data Monitoring Committee. Statistically significant and clinically meaningful improvements in progression-free survival (PFS) and overall response rate (ORR) were also observed in the all-randomized patient population.

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 and will be submitted to regulatory authorities. Merck has an extensive clinical development program evaluating KEYTRUDA in gastrointestinal cancers, which includes KEYNOTE-811 in first-line advanced HER2-positive gastric cancer, KEYNOTE-585 in early-stage gastric cancer, and further exploration in advanced/metastatic gastric cancer in LEAP-015.

Merck is continuing to study KEYTRUDA for multiple uses in hepatobiliary, esophageal, pancreatic and colorectal cancers.