Of the 106 pts, 99 (93.4%) had GI tumors. Confirmed ORR in dMMR pts was 38.7% (95% CI: 29.4, 48.6), with a complete response rate of 7.5%. ORR was consistent across tumor type (Table). Dostarlimab demonstrated durable antitumor activity in a cohort of dMMR solid tumor pts, the majority of whom had GI cancers.