The PD-1/PD-L1 pathway has emerged as a critical target in colorectal cancer (CRC) immunotherapy, with pembrolizumab, nivolumab, and dostarlimab demonstrating significant clinical efficacy, particularly in microsatellite instability-high (MSI-H) and mismatch repair-deficient (dMMR) tumors. The gene discussed is PDCD1; the disease is colorectal carcinoma.