Multicenter phase 2 trial of iparomlimab (QL1604) for MSI-H or dMMR unresectable or metastatic solid tumors

Iparomlimab (QL1604) is a novel humanized anti-PD-1 mAb. A multicenter phase 2 trial in China evaluated iparomlimab in patients with microsatellite instability-high (MSI-H) or mismatch repair-deficient (dMMR) unresectable or metastatic solid tumors. The primary endpoint was objective response rate assessed by independent radiological review. The confirmed ORR was 50.0% (95% CI 38.8-63.2) with complete response in 6.7%. Among patients with colorectal cancer the ORR was 57.9% (95% CI 40.8-73.7) with complete response in 7.9%. The incidence of treatment-related adverse events was 90.8% (any grade) and 20.8% (grade 3 or 4). There were no grade 5 TRAEs. The authors conclude that iparomlimab showed encouraging antitumor activity and a tolerable safety profile among patients with MSI-H or dMMR unresectable or metastatic solid tumors.