PDCD1 and colorectal carcinoma: Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the second leading cause of cancer-related mortality worldwide.1,2 Despite recent advances in immunotherapies that have revolutionized cancer treatment, their effectiveness in CRC remains limited.3,4 Although CRC characterized by microsatellite instability-high (MSI-H) responds favorably to PD1 blockade, this subset represents less than 15% of all CRC cases.