Merck's Keytruda combo achieves survival goal in Phase III gastric cancer trial

Merck & Co.'s Keytruda (pembrolizumab) has shown a significant improvement in survival rates when paired with trastuzumab and chemotherapy for first-line treatment in patients with HER2-positive advanced gastric or gastroesophageal junction (GEJ) adenocarcinoma. The recent results build on promising progression-free survival (PFS) data from the Phase III KEYNOTE-811 trial announced last year.

Based on earlier findings showing an improved objective response rate and the durability of response, the FDA granted accelerated approval for Keytruda. This approval is for its use in combination with trastuzumab, and fluoropyrimidine- and platinum-containing chemotherapy, targeting adults with locally advanced unresectable or metastatic HER2-positive gastric or GEJ adenocarcinoma whose tumors express PD-L1.

In previously reported PFS results, Merck had noted a "trend toward improvement" in overall survival (OS). However, this improvement did not reach statistical significance at the time. These findings were detailed at the European Society for Medical Oncology (ESMO) congress last year. Among patients with PD-L1-expressing tumors, the Keytruda regimen showed a median OS of 20 months, compared to 15.7 months for those treated with trastuzumab and chemotherapy alone.

On Wednesday, Merck announced that the final analysis revealed Keytruda, when combined with trastuzumab and chemotherapy, demonstrated a statistically significant and clinically meaningful improvement in OS. This was especially notable in patients whose tumors expressed PD-L1. Detailed results are expected to be presented at an upcoming medical meeting.

Keytruda has already received approval for several indications in the United States, including its use in combination with fluoropyrimidine- and platinum-containing chemotherapy for first-line treatment of adults with locally advanced unresectable or metastatic HER2-negative gastric or GEJ adenocarcinoma. Sales of Keytruda have surged, increasing by 20% year-over-year to reach $6.9 billion in the first quarter, surpassing analyst expectations of $6.7 billion.

The latest findings from the KEYNOTE-811 trial reinforce Keytruda’s potential as a crucial component in the treatment of HER2-positive advanced gastric or GEJ adenocarcinoma. Moving forward, the anticipated detailed presentation will likely provide further insights into the efficacy and clinical benefits of this combination therapy, potentially influencing future treatment protocols and guidelines.