MRC1 and neoplasm: Though the exceptionally high burden of somatic mutations in LS was favored in the anti-PD-1 treatment of patients across 12 different tumor types including colorectal cancer (41, 42), approximately half of the patients with MMR defect did not respond to ICT; only 53% of MMR-deficient patients showed objective radiographic responses, and 21% of patients had CRs (42).