Using a combination of genomics, shotgun MS immunopeptidomics, and targeted MS, they found that (i) MS-identified neoepitopes are a rich source of tumor rejection–mediating antigens, (ii) neoantigens derive from passenger mutations, and (iii) binding affinity and CD8+ T-cell responses in tumor-bearing hosts are poor predictors of antitumor activity in vivo. This evidence concerns the gene CD8A and neoplasm.