PDCD1 and metastatic neoplasm: This is relevant because it is well-established and FDA-approved that patients with CRC and other unresectable or metastatic tumors with MSI-H positive values respond favorably to monoclonal antibody (mAB) therapies, such as pembrolizumab, targeting immune checkpoints like programmed cell death protein 1 (PD-1) or programmed cell death ligand 1 (PD-L1) [36].