PDCD1 and colorectal cancer: To evaluate the efficacy of KD033 in both human PD-L1 positive and negative tumors, a single intravenous (IV) injection of 3 mg/kg were administered to human-PD-1/PD-L1 knock-in C57/Bl6 mice subcutaneously transplanted with either human-PD-L1 positive- or negative- MC38 (hPDL1+ or hPDL1- MC38) colorectal cancer cells.