Patient-specific tumor peptide–Major Histocompatibility Complex (pMHC)

Patient-specific tumor peptide–Major Histocompatibility Complex (pMHC) molecules represent the fundamental unit of recognition for the adaptive cellular immune system in oncology. These complexes are formed when intracellular tumor-specific proteins, often resulting from somatic mutations (neoantigens), are processed into short peptides and presented on the cell surface by MHC (Human Leukocyte Antigen or HLA in humans) molecules (Nature Reviews Cancer, 2021). Tumor-infiltrating lymphocytes (TILs) possess endogenous T-cell receptors (TCRs) that have been naturally selected to recognize these unique pMHC signatures, distinguishing malignant cells from healthy tissue (Science, 2014). Therapeutic interventions like TIL therapy (e.g., Lifileucel) involve extracting, expanding, and re-infusing these T cells to exploit this recognition mechanism (NEJM, 2024). Additionally, personalized neoantigen vaccines aim to prime the immune system to specifically target these patient-unique pMHC complexes. While highly effective, the success of targeting pMHC is often limited by tumor-mediated immune evasion, such as the loss of HLA expression, and the technical challenge of identifying the most immunogenic peptides for each individual patient.

Other names

Neoantigen-HLA complexTumor-specific antigen-MHC complexNeoepitope-MHC complexTumor peptide-MHC

The T-cell receptor (TCR) on a T-lymphocyte specifically recognizes and binds to the peptide-MHC complex, initiating an immunological synapse that triggers T-cell proliferation and cytotoxic activity against the target cell.