Tumor-specific mutant peptide–MHC class I complex

Tumor-specific mutant peptide–MHC class I complexes are molecular assemblies formed when intracellular proteins containing tumor-specific mutations (“neoantigens”) are processed into short peptides and loaded onto major histocompatibility complex class I molecules. These complexes are displayed on the surface of tumor cells and recognized by cytotoxic CD8+ T lymphocytes, which can then selectively kill the presenting cancer cell. The specificity arises from the unique amino acid changes in the mutant peptides that distinguish them from normal self-proteins, allowing immune targeting while sparing healthy tissue. The formation and presentation of these complexes is central to anti-tumor immunity and underpins several modern immunotherapies, including personalized cancer vaccines designed to elicit strong CD8+ T cell responses against patient-specific neoepitopes. However, only a minority of such presented neoepitopes effectively control tumors; their activity depends on structural features that enable robust binding to both MHC-I molecules and diverse T-cell receptors while avoiding central tolerance mechanisms[3]. Loss or downregulation of MHC-I expression is a common mechanism by which tumors evade this immune surveillance, posing challenges for therapy effectiveness[1].

Other names

Tumor neoantigen–MHC class I complexNeoepitope–MHC class I complexMutant peptide–HLA class I complexTumor-specific antigen–MHC class I complex

Presentation of tumor-derived mutant peptides on MHC-I enables recognition and killing of tumor cells by cytotoxic CD8+ T cells[3][4].