Merck announces results from KEYNOTE-811 trial at ESMO Congress

Merck announced results from the Phase 3 KEYNOTE-811 trial evaluating Keytruda, Merck’s anti-PD-1 therapy, in combination with trastuzumab, fluoropyrimidine- and platinum-containing chemotherapy, for the first-line treatment of patients with human epidermal growth factor receptor 2, or HER2,-positive locally advanced unresectable or metastatic gastric or gastroesophageal junction, orGEJ, adenocarcinoma. These data are being presented during a proffered paper session at the European Society for Medical Oncology Congress 2023 and are being discussed with regulatory authorities worldwide. After a median follow-up of 28.4 months, the Keytruda regimen demonstrated a statistically significant improvement in progression-free survival, or PFS, in the intention-to-treat, or ITT, advanced HER2-positive study population, reducing the risk of disease progression or death by 28% compared to trastuzumab and chemotherapy alone. The Keytruda regimen also demonstrated a clinically meaningful improvement in PFS in patients whose tumors expressed PD-L1, reducing the risk of disease progression or death by 30% compared to trastuzumab and chemotherapy alone. Based on a pre-specified subgroup analysis, the improvement in PFS observed in the ITT population was limited to patients whose tumors expressed PD-L1. In the study, more than 80% of patients’ tumors expressed PD-L1. At a subsequent interim analysis, a positive trend in overall survival, the trial’s other primary endpoint, was observed for the Keytruda regimen versus trastuzumab and chemotherapy alone in the ITT population and the PD-L1 subgroup. Among patients whose tumors expressed PD-L1, median OS was 20 months for those receiving the Keytruda regimen versus 15.7 months for those receiving trastuzumab and chemotherapy alone. These OS results did not reach statistical significance at this interim analysis; follow-up is ongoing for a future planned OS analysis for this trial.