Human Leukocyte Antigen class I-melanoma peptide complex (HLA-I-peptide complex)

Human Leukocyte Antigen (HLA) class I-melanoma peptide complexes are molecular assemblies on the surface of melanoma cells that present intracellularly derived peptides to CD8+ T cells. These complexes are formed when HLA class I molecules (typically HLA-A, -B, or -C) bind to short peptide fragments derived from melanoma-associated antigens (MAAs) such as gp100, MART-1, MAGE-A4, or NY-ESO-1, or from tumor-specific mutations known as neoantigens [PMID: 30104441]. Recognition of these peptide-MHC (pMHC) targets by T-cell receptors (TCRs) is the fundamental mechanism of the cellular immune response against cancer [PMID: 28434166]. In clinical oncology, these complexes serve as highly specific targets for advanced immunotherapies, including TCR-engineered T-cell therapies (TCR-T) and Immune mobilizing monoclonal TCRs Against Cancer (ImmTACs) like tebentafusp [PMID: 34551229]. Because these targets are HLA-restricted, therapeutic efficacy is often dependent on the patient's specific HLA genotype, most commonly HLA-A*02:01 [PMID: 31070518]. Challenges in targeting these complexes include the downregulation of HLA expression by tumor cells as an escape mechanism and the risk of off-target toxicity if the target peptide is shared by proteins in healthy tissues [PMID: 29669035].

Other names

pMHC complexMHC class I-peptide complexMelanoma-associated antigen-HLA complexHLA-restricted melanoma antigenPeptide-HLA complexHLA-A*02:01-melanoma peptide complex

Drugs targeting these complexes typically utilize engineered T-cell receptors (TCRs) or TCR-mimetic domains to bind the specific peptide-HLA combination on the cell surface, leading to T-cell redirection, activation, and subsequent lysis of the melanoma cell.