Tumor-associated antigen peptide-major histocompatibility complex (pMHC) (pMHC)

Tumor-associated antigen peptide-major histocompatibility complexes (pMHC) are specialized molecular structures on the surface of cells that present fragments of intracellular proteins to the immune system. These complexes are formed when proteins are degraded by the proteasome into short peptides, which are then loaded onto MHC (or HLA in humans) molecules and transported to the cell membrane [Nature Reviews Immunology, 2020]. In malignant cells, these peptides often derive from mutated proteins (neoantigens), overexpressed proteins, or cancer-testis antigens, serving as specific markers for immune recognition [Frontiers in Oncology, 2021]. By targeting these pMHC complexes, therapeutic agents can direct the immune system to identify and destroy cancer cells that might otherwise remain hidden from traditional antibody-based therapies that only recognize surface-bound proteins. Therapeutic interventions targeting pMHC include T-cell receptor-engineered T-cell (TCR-T) therapies, bispecific T-cell engagers (BiTEs), and cancer vaccines [Journal of Hematology & Oncology, 2023]. For instance, Tebentafusp is a bispecific protein that redirects T-cells to kill melanoma cells presenting the gp100 peptide on HLA-A*02:01 [New England Journal of Medicine, 2021]. While highly potent, these therapies require precise patient selection based on HLA typing and carry risks of off-target toxicity if the targeted peptide sequence is shared by proteins in healthy tissues [Science Translational Medicine, 2013]. Despite these challenges, pMHC targeting remains a cornerstone of modern precision oncology, offering a pathway to target the vast "undruggable" intracellular proteome.

Other names

pMHCTAA-pMHCHLA-restricted antigenTumor-specific antigen-MHC complexNeoantigen-MHC complexCancer-testis antigen-MHC complex

T-cell receptor (TCR) mediated recognition and subsequent T-cell activation leading to targeted lysis of cells presenting specific intracellularly derived peptides on HLA molecules [Nature Reviews Drug Discovery, 2021].