PDCD1 and colorectal carcinoma: In summary, on the basis of the gene expression profile of genes relevant to therapy (a), it may not be surprising if PD1 blockers do not show promising results in this CRC population, but some other ICI, such as CTLA4 or HAVCR2 blockers, may have promising results in the MSI subgroup; (b) the possibility of platinum drug resistance may be low, irrespective of age of onset in this population.