Review of Key Findings from CheckMate 648 and KEYNOTE-590

This discussion offers a focused review of two pivotal clinical trials, CheckMate 648 and KEYNOTE-590, that established the value of adding a PD-1 inhibitor to first-line platinum-based chemotherapy in advanced esophageal squamous cell carcinoma (ESCC). In CheckMate 648, nivolumab plus chemotherapy produced a meaningful overall survival improvement compared with chemotherapy alone, with the greatest benefit observed in patients whose tumors expressed PD-L1 (measured as tumor-cell ≥1%). Similarly, KEYNOTE-590 demonstrated that pembrolizumab combined with chemotherapy significantly prolonged overall survival versus chemotherapy alone, particularly in patients with PD-L1 CPS ≥1. Across both studies, median survival in the immunotherapy arms approached or exceeded the one-year mark, reinforcing the clinical impact of these combinations. Safety findings were consistent with known profiles of PD-1 inhibitors and cytotoxic therapy, with no unexpected signals. This segment highlights how these landmark trials have helped define chemo-immunotherapy as a key first-line standard in advanced ESCC.