PDCD1 and colorectal carcinoma: Anti-programmed cell death 1 (anti-PD-1) immunotherapy, as novel immunotherapy drug, has achieved favorable results in several advanced cancers.2,3 In contrast to other tumor types, CRC patients who benefit from anti-PD-1 are dismally limited.4,5 Therefore, how to make more CRC patients benefit from immunotherapy remains a hot topic in this field.