Patient-specific tumor-associated antigen peptide-MHC complex (Neoantigen-pMHC)

Patient-specific tumor-associated antigens (TAAs), primarily neoantigens, are unique peptides derived from non-synonymous somatic mutations within a patient's tumor. These antigens are processed and presented on the cell surface by Major Histocompatibility Complex (MHC) Class I molecules, forming peptide-MHC (pMHC) complexes that act as the definitive markers of 'non-self' for the immune system [1, 9]. These complexes are specifically recognized by the T-cell receptors (TCRs) of a highly specialized subset of CD8+ tumor-infiltrating lymphocytes (TILs) characterized by the co-expression of CD39 and CD103. This double-positive (DP) phenotype identifies the truly tumor-reactive fraction of TILs, which are often exhausted but possess the highest specificity for neoantigens compared to bystander T cells [1, 8]. In clinical oncology, these pMHC complexes are the focal point for personalized immunotherapies, including neoantigen-targeted vaccines and adoptive cell therapies (ACT). By isolating and expanding CD39+CD103+ TILs or cloning their TCRs for use in TCR-engineered T-cell (TCR-T) therapy, researchers can direct a potent immune response against the tumor while minimizing damage to healthy tissues [6, 10]. The use of these specific biomarkers allows for the enrichment of therapeutic products with cells that have already demonstrated an ability to recognize the patient's unique tumor landscape. However, the success of targeting these complexes is often challenged by the high degree of intratumoral heterogeneity and the potential for tumors to undergo immunoediting, leading to the loss of the targeted neoantigens [11, 12].

Other names

Neoantigen-MHC complexTumor-specific antigen-MHC complexTSA-pMHCTAA-pMHCNeoepitope-MHC complexTumor-reactive TIL target

These complexes serve as the primary recognition target for the T-cell receptor (TCR) on CD8+ cytotoxic T lymphocytes. Binding of the TCR to the specific peptide-MHC complex, in the presence of costimulatory signals, triggers T-cell activation, clonal expansion, and the release of cytotoxic molecules such as perforin and granzymes to induce apoptosis in the target tumor cell [1, 6].