Louis, MO, USA, showed in their chemically induced sarcoma model in mice that such killer T cells activated after the PD-1 blockade recognized mutated peptide antigens (so called ‘neoantigens’) derived from the chemically mutagenized genome of the sarcoma cell line in the context of the major histocompatibility complex (MHC) molecules [34]. The gene discussed is HLA-C; the disease is sarcoma.