In BALB/c-hPD-1/hPD-L1/hCD137 mice implanted with the murine CT26 colorectal cancer cell line overexpressing human PD-L1 (CT26-hPD-L1), 7 days after the third antibody injection, IBI319 showed an enhanced efficacy compared to the αPD-1 mAb and αCD137 mAb (undetectable efficacy) (Fig. 3a) and was as efficacious as the αPD-1 mAb + αCD137 mAb combination treatment (Supplementary Fig. 3c in a separate experiment), indicating the contributions from both the anti-PD-1 and anti-CD137 arms of IBI319. This evidence concerns the gene PDCD1 and colorectal cancer.