Phase III KEYNOTE-811 trial met dual primary endpoint of overall survival as first-line treatment in patients with HER2-positive advanced gastric or gastroesophageal junction adenocarcinoma – Merck

Merck Inc., known as MSD outside of the United States and Canada, announced that the Phase III KEYNOTE-811 trial evaluating Keytruda (pembrolizumab), Merck’s anti-PD-1 therapy, in combination with trastuzumab and fluoropyrimidine- and platinum-containing chemotherapy met its dual primary endpoint of overall survival (OS) for the first-line treatment of patients with human epidermal growth factor receptor 2 (HER2)-positive locally advanced unresectable or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma.

Based on results from KEYNOTE-811 , Keytruda is approved in combination with trastuzumab and fluoropyrimidine- and platinum-containing chemotherapy for the first-line treatment of adults with locally advanced unresectable or metastatic HER2-positive gastric or GEJ adenocarcinoma whose tumors express PD-L1 (CPS greater than 1) as determined by an FDA-approved test. This indication is approved by the FDA under accelerated approval regulations based on the objective response rate (ORR) and durability of response demonstrated at an earlier analysis. Continued approval of this indication may be contingent upon verification and description of clinical benefit at the final analysis of the KEYNOTE-811 study.

In the final analysis of this trial , Keytruda in combination with trastuzumab and chemotherapy demonstrated a statistically significant and clinically meaningful improvement in OS compared to placebo in combination with trastuzumab and chemotherapy in the intention-to-treat (ITT) study population, with the greatest benefit observed in patients whose tumors expressed PD-L1 (CPS ?1). 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 shared with regulatory authorities worldwide.

As previously announced, at an earlier interim analysis, KEYNOTE-811 met the other dual primary endpoint of progression-free survival (PFS) and these results were presented at the European Society for Medical Oncology (ESMO) Congress 2023.