In the study by Yue et al., colorectal cancer (CRC) patients undergoing PD-1 blockade therapy with IB1308 were stratified into four groups based on PD-L1 expression levels on circulating tumor cells(CTCs): PD-L1negative (MFI<50), PD-L1low (50≤MFI<100), PD-L1medium (100≤MFI<150), and PD-L1high (MFI≥150). The gene discussed is PDCD1; the disease is colorectal cancer.