Patient-specific neoantigen peptide–human leukocyte antigen complex (NeoAg-HLA complex)

A patient-specific neoantigen peptide–HLA complex is a molecular assembly consisting of a tumor-specific mutated peptide fragment bound to a Human Leukocyte Antigen (HLA) molecule on the surface of a cancer cell. These complexes are the primary targets for the adaptive immune system's recognition of malignancy, as neoantigens arise from somatic mutations unique to the patient's tumor and are absent from healthy tissue (Nature Reviews Cancer, 2021). Because these antigens are not present in the germline, they bypass central thymic tolerance, allowing for the generation of high-affinity T-cell responses without the typical risk of systemic autoimmunity associated with shared tumor antigens (Science, 2015). In the context of drug development, this complex is targeted by personalized immunotherapy platforms, including mRNA and DNA vaccines that encode the neoepitopes to stimulate endogenous T-cell expansion, and adoptive cell therapies like TCR-T, where T cells are engineered to express receptors specific to the patient's unique pHLA (Cell, 2020). The efficacy of these treatments depends heavily on the accurate bioinformatic prediction of which mutations will be successfully processed and presented by the patient's specific HLA alleles. Current clinical challenges include the high heterogeneity of neoantigen expression within tumors and the potential for tumors to escape immune pressure by downregulating HLA expression (Journal of Clinical Investigation, 2019).

Other names

Neoantigen-MHC complexTumor-specific antigen-HLA complexpHLA complexNeoepitope-HLA complexPersonalized neoantigen-MHC

The complex acts as a ligand for T-cell receptors (TCRs). Therapeutic interventions either prime the immune system to recognize these complexes (vaccines) or provide engineered T-cells (TCR-T) and bispecific molecules that bind specifically to the neoantigen-HLA interface to trigger tumor cell lysis.