Patient-specific peptide–Human Leukocyte Antigen complex (pHLA complex)

Patient-specific peptide–Human Leukocyte Antigen (pHLA) complexes are the fundamental units of immune recognition, consisting of a short peptide fragment bound to an HLA molecule on the cell surface (Nature Reviews Immunology, 2019). These complexes are recognized by T-cell receptors (TCRs), which trigger an immune response against cells presenting non-self or mutated self peptides (PubMed, 31534224). In oncology, pHLA complexes containing neoantigens—peptides derived from tumor-specific mutations—are the primary targets for personalized immunotherapies (NCI, 2023). Because HLA genes are highly polymorphic and tumor mutations are often unique to an individual, these targets are inherently patient-specific (Frontiers in Immunology, 2020). Targeting pHLA complexes allows for high precision, potentially minimizing damage to healthy tissues that do not present the specific mutated peptide (Science, 2021). Therapeutic strategies include personalized cancer vaccines that prompt the body to produce these complexes and TCR-T cell therapies that provide engineered cells to recognize them (Nature, 2023). The identification of these complexes typically involves whole-exome sequencing and HLA typing followed by bioinformatic prediction of peptide-binding affinity (PubMed, 30241486). Despite their potential, challenges such as HLA downregulation by tumors and the risk of cross-reactivity with healthy tissues remain significant hurdles (Journal of Clinical Investigation, 2022).

Other names

Neoantigen-HLA complexpMHC complexPeptide-Major Histocompatibility ComplexTumor-specific peptide-MHC complexPersonalized neoantigen-MHC

Presentation of specific intracellularly derived peptides to T-cell receptors (TCRs) to initiate a targeted immune response against cells expressing the target antigen.