Merck's Keytruda Combo Therapy Hits Primary Goal In Patients With Rare Form Of Gastric Cancer

Merck & Co Inc MRK announced topline data from the Phase 3 KEYNOTE-811 trial of Keytruda (pembrolizumab) plus trastuzumab and chemotherapy for human epidermal growth factor receptor 2 (HER2)-positive advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma. 

The study met one of its dual primary endpoints of progression-free survival (PFS). 

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 (ITT) 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 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. 

Also Read: After Back To Back Failure For Keytruda Plus Lenvima, Merck Touts Durable Clinical Benefit For The Combo In Advanced Kidney Cancer.

In May 2021, Keytruda was approved in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy for the first-line treatment of patients with locally advanced unresectable or metastatic HER2-positive gastric or GEJ adenocarcinoma in the U.S. 

The FDA approved this indication under accelerated approval based on objective response rate (ORR) data from KEYNOTE-811.

A trend toward improvement in overall survival (OS), the trial's other primary endpoint, was observed in the ITT population for patients who received the Keytruda combination versus placebo combined with trastuzumab and chemotherapy; however, these results did not meet statistical significance.

Price Action: MRK shares are up 0.05% at $109.45 on the last check Friday.