Sat Sep 14 07:15:48 UTC 2024: ## Merck Announces Positive Overall Survival Results for KEYTRUDA in HER2-Positive Gastric Cancer

**RAHWAY, NJ -** Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced positive overall survival (OS) results from the final analysis of the Phase 3 KEYNOTE-811 trial. The trial evaluated KEYTRUDA® (pembrolizumab), Merck’s anti-PD-1 therapy, in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy, for the first-line treatment of adults with locally advanced unresectable or metastatic human epidermal growth factor receptor 2 (HER2)-positive gastric or gastroesophageal junction (GEJ) adenocarcinoma.

The results, presented at the European Society for Medical Oncology (ESMO) Congress 2024 and published in the *New England Journal of Medicine*, show that the KEYTRUDA regimen significantly improved OS compared to trastuzumab and chemotherapy alone.

**Key Findings:**

* The KEYTRUDA regimen reduced the risk of death by 20% in the intention-to-treat (ITT) population, with a median OS of 20.0 months versus 16.8 months for the control group.
* Patients whose tumors expressed PD-L1 (Combined Positive Score [CPS] ≥1) showed even greater benefit, with a 21% reduction in the risk of disease progression or death. Median OS was 20.1 months versus 15.7 months for the control group.

“These overall survival results from the KEYNOTE-811 trial are encouraging and show that adding pembrolizumab to trastuzumab and chemotherapy can extend the lives of certain patients with HER2-positive and PD-L1 positive gastric and gastroesophageal cancer,” said Dr. Yelena Y. Janjigian, chief attending physician, gastrointestinal oncology, Memorial Sloan Kettering Cancer Center, and global lead principal investigator for the KEYNOTE-811 trial.

**Regulatory Approvals:**

In the U.S., KEYTRUDA, in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy, is indicated 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 ≥1). This indication was approved under accelerated approval based on tumor response rate and durability of response, but continued approval may be contingent upon verification and description of clinical benefit in confirmatory trials.

The European Commission approved the same combination in August 2023 based on PFS results from the KEYNOTE-811 trial.

**Next Steps:**

Merck is continuing its extensive clinical development program evaluating KEYTRUDA in various gastrointestinal cancers, aiming to provide promising new treatment options to patients.

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