PDCD1 and colorectal carcinoma: The expression of PD-1, PD-L1, and CTLA-4 in the TRG clusters was explored, and the results showed that these three immune checkpoints had higher expression in TRG cluster B than in cluster A. PRDEGs between the two TRG clusters were further determined, and the patients with CRC were split into three gene clusters based on PRDEGs expression.