Triple therapy for unresectable or metastatic HER2-positive gastric cancer

HER2 amplification or overexpression occurs in approximately 20% of advanced gastric of gastro-esophageal junction adenocarcinomas. More than a decade ago, combinationtherapy with the anti-HER2 antibody trastuzumab and chemotherapy became the standard first-line treatment for patients with these types of tumors. The phase 3 KEYNOTE-811 evaluated addition of pembrolizumab versus placebo to trastuzumab and chemotherapy for unresectable or metastatic, HER2-positive gastric or gastro-esophageal junction adenocarcinoma. The protocol-specified first interim analysis of the study found that adding pembrolizumab to trastuzumab and chemotherapy markedly reduced tumor size, induced complete responses in some participants, and significantly improved objective response rate.