MSH3 and cancer: We investigated the tumor neoantigens and immune infiltrates in cases affected by germline variants/somatic mutations (mut) and/or methylation (me) of 5 MMR genes: MLH1, MSH3, MSH2, MSH6, and PMS2. In the pan-cancer cohort of 10,080 cases (hypermutators and non-hypermutators), the frequencies of MMR-d cases, affected MMR genes, and alteration types varied across cancer types (Figure 5A).