Tumor-associated peptide-MHC complex (pMHC)

Patient-specific tumor-associated peptide–MHC (pMHC) complexes are molecular assemblies on the surface of tumor cells that present intracellularly derived peptides to the immune system [1, 9]. These complexes consist of a peptide fragment, often a neoantigen resulting from a tumor-specific mutation, bound within the groove of a Major Histocompatibility Complex (MHC) molecule, also known as Human Leukocyte Antigen (HLA) in humans [7, 16]. They serve as the fundamental recognition unit for T-cell receptors (TCRs), enabling the adaptive immune system to distinguish malignant cells from healthy ones [8, 15]. Because neoantigens are unique to an individual patient's tumor, these pMHC complexes represent highly specific therapeutic targets for personalized immunotherapies, including neoantigen vaccines and TCR-engineered T-cell (TCR-T) therapies [6, 12]. Targeting these complexes aims to induce a potent and selective cytotoxic T-cell response against the tumor while minimizing damage to normal tissues that lack the specific peptide-MHC combination [3, 13]. However, challenges such as low surface density of the complexes and the potential for tumor immune escape through MHC downregulation remain significant hurdles in clinical development [2, 15].

Other names

pHLA complexNeoantigen-MHC complexTumor-specific antigen-MHC complexMHC-peptide complexAntigen-MHC complexPatient-specific tumor-associated peptide-MHC complex

Recognition of the peptide-MHC complex by T-cell receptors (TCRs) or TCR-mimic antibodies, which triggers T-cell activation, secretion of cytotoxic granules such as perforin and granzymes, and direct lysis of the target tumor cell [1, 15].