Multicenter phase 2 study of serplulimab for previously treated MSI-H/dMMR unresectable or metastatic solid tumors

Microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) tumors have a high response rate to immunotherapy. Serplulimab is a novel anti-PD-1 monoclonal antibody. A multicenter phase 2 trial in China evaluated serplulimab in patients with previously treated unresectable or metastatic MSI-H/dMMR solid tumors. The objective response rate was 38.2% (95% CI 26-7-50.8), while another 29.4% of patients had stable disease, contributing to a disease control rate of 67.6% (95% CI 55.2-78.5). Median duration of response was not reached with median follow-up of 7.7 months. Grade 3 or higher treatment-emergent adverse events were seen in 49.1% of patients. Immune-related adverse events were seen in 48.1%. The authors conclude that serplulimab had a durable antitumor effect and a manageable safety profile in previously treated patients with MSI-H solid tumors.