PDCD1 and metastatic colorectal cancer: Personalized treatments for metastatic colorectal cancer (mCRC) are currently limited to a small number of drugs targeting specific molecular markers, such as anti-VEGF, anti-EGFR for RAS wild-type tumors, encorafenib for BRAF (V600E)-mutated tumors, programmed death-ligand 1/programmed cell death protein 1 (PDL-1/PD-1) inhibitors for mismatch repair-deficient (dMMR)/high-microsatellite-instability (MSI-H) tumors, and KRAS tyrosine kinase inhibitors for KRAS G12C mutated tumors [1].