Major histocompatibility complex class I–tumor peptide antigen complex (MHC-I/tumor peptide antigen complex (sometimes abbreviated pMHC-I))

The major histocompatibility complex class I–tumor peptide antigen complex consists of an MHC class I molecule bound to a short peptide (typically 8–10 amino acids) derived from a tumor-associated protein, assembled in the endoplasmic reticulum through the antigen-processing machinery (including TAP, ERAAP, calnexin, tapasin, etc.) and presented on the cell surface[1][3][6]. Recognition of this complex by a specific T-cell receptor (TCR) on cytotoxic CD8+ T cells is the critical step for adaptive immune responses against tumors, driving the development of targeted immunotherapies, including engineered TCRs and peptide/MHC-targeting biologics[4][7]. Tumors frequently escape immune detection by downregulating MHC or modifying the presented peptides, constituting a significant therapeutic challenge. Extensive MHC polymorphism results in a highly variable repertoire of pMHC complexes between individuals, shaping both immune recognition and therapeutic design[2][5]. If additional molecular or disease-specific detail is needed, specifying the tumor antigen (e.g., NY-ESO-1, MAGEA4) and the MHC allele (e.g., HLA-A*02:01) is essential, as each unique combination defines a distinct target for immunotherapy[4][7].

Other names

Peptide–MHC complexpMHC (peptide-MHC)Tumor antigen–MHC complexTumor-associated antigen–MHC class I complexMHC–peptide complex

Induction of T cell–mediated cytotoxicity (drugs exploit T cell recognition of pMHC to direct killing of tumor cells); Enhancement of antigen presentation (modulate pathways that boost MHC-I surface expression); Blocking immune evasion (inhibition of pathways leading to reduced MHC expression or loading).