HLA-A*02:01-restricted melanoma-associated antigen peptide-MHC complexes (HLA-A2/MAA pMHC)

HLA-A*02:01-presented MART-1, gp100, and tyrosinase peptide epitopes are specific peptide-MHC (pMHC) complexes that serve as critical targets for melanoma immunotherapy (Kawakami et al., 1994). These epitopes are derived from lineage-specific proteins—MART-1 (Melan-A), gp100 (PMEL), and tyrosinase—which are highly expressed in melanocytes and the majority of malignant melanoma cells (UniProt Q16655; UniProt P40967; UniProt P14679). The HLA-A*02:01 allele is a common MHC Class I molecule that presents these intracellularly processed peptides to the surface for surveillance by CD8+ T cells. Recognition of these complexes by high-affinity T-cell receptors (TCRs) triggers the release of cytotoxic granules, leading to the targeted destruction of the presenting cancer cell. Because these antigens are overexpressed in tumors but also present in normal melanocytes, they are considered differentiation antigens rather than neoantigens. Therapeutic approaches targeting these complexes include TCR-engineered T-cell (TCR-T) therapies, bispecific T-cell engagers like tebentafusp, and various peptide-based vaccines (Nathan et al., 2021). Clinical efficacy is often monitored through the expression levels of the parent proteins and the presence of the HLA-A*02:01 genotype in patients. A significant challenge in targeting these epitopes is the potential for on-target, off-tumor toxicity, which can manifest as autoimmune destruction of healthy melanocytes in the skin, eyes, and inner ear.

Other names

MART-1/HLA-A*02:01gp100/HLA-A*02:01Tyrosinase/HLA-A*02:01Melanoma-associated antigen (MAA) epitopesMelan-A/HLA-A2 complexPMEL/HLA-A2 complex

T-cell receptor (TCR) mediated recognition of specific peptide-MHC complexes on the surface of tumor cells, leading to the activation of CD8+ cytotoxic T lymphocytes and subsequent tumor cell apoptosis via perforin and granzyme release.