Tumor-associated peptide-Major Histocompatibility Complex (pMHC)

The Tumor-associated peptide-Major Histocompatibility Complex (pMHC) is a molecular assembly consisting of a short peptide fragment derived from a tumor-associated or tumor-specific protein bound to a Major Histocompatibility Complex (MHC) molecule on the surface of a cancer cell [1]. These complexes serve as the primary signal for the adaptive immune system to identify and eliminate malignant cells by presenting intracellular antigens to the extracellular environment. Specifically, CD8+ T cells expressing the PD-1 marker are often enriched for those that recognize these pMHCs with high affinity, representing a pool of tumor-reactive but potentially exhausted lymphocytes [1, 2]. Targeting these complexes is a cornerstone of modern immunotherapy, including the development of T-cell receptor (TCR) engineered T-cell therapies and TCR-bispecific molecules that bypass the need for endogenous T-cell activation [3, 4]. By specifically binding to these pMHCs, therapeutic agents can redirect the immune system to selectively eliminate malignant cells while sparing healthy tissue. However, challenges such as HLA downregulation and the risk of cross-reactivity with similar peptides in normal tissues remain significant hurdles in clinical application [5, 6].

Other names

Tumor-associated pMHCNeoantigen-MHC complexTumor-specific antigen-MHC complexHLA-peptide complexTA-pMHCAntigen-presenting complex

Recognition by specific T-cell receptors (TCRs) on CD8+ T cells or TCR-mimetic therapeutic molecules, leading to the formation of an immunological synapse and subsequent release of perforins and granzymes to induce apoptosis in the target tumor cell [3, 5].