HLA-A2-restricted melanoma-associated antigen peptide-MHC complex (HLA-A2/MAA pMHC)

HLA-A2-restricted melanoma-associated antigen (MAA) epitopes presented on MHC class I are molecular complexes consisting of the HLA-A*02:01 protein and specific peptide fragments derived from intracellular melanoma antigens such as gp100, MART-1, or MAGE-A4 [PMID: 34161744]. These complexes are displayed on the surface of malignant cells, where they serve as the primary recognition targets for the T-cell receptors (TCRs) of CD8+ cytotoxic T lymphocytes [PMID: 11015445]. In therapeutic contexts, these pMHC complexes are targeted by innovative modalities including TCR-engineered T-cell therapies (TCR-T) and bispecific T-cell engagers like ImmTACs [PMID: 31914351]. A prominent example is Tebentafusp, which targets the gp100 peptide-HLA-A2 complex to treat metastatic uveal melanoma [PMID: 34551227]. Because these targets are highly specific to the HLA-A2 haplotype and the expression of specific tumor antigens, patient selection requires both HLA typing and immunohistochemical confirmation of antigen presence [PMID: 28844815]. Clinical challenges include managing cytokine release syndrome and potential 'on-target, off-tumor' effects in healthy tissues that contain melanocytes, such as the skin and eyes [PMID: 35235774].

Other names

HLA-A*02:01-restricted melanoma antigen complexpMHC complex (Melanoma)HLA-A2/gp100 complexHLA-A2/MART-1 complexHLA-A2/MAGE-A4 complexHLA-A2/NY-ESO-1 complex

Drugs targeting these complexes utilize high-affinity T-cell receptors (TCRs) or TCR-mimetic domains to bind the specific peptide-HLA complex. This binding redirects T-cell activity to the tumor cell, either through bispecific engagers that recruit polyclonal T cells or through genetically modified TCR-T cells that directly execute perforin/granzyme-mediated lysis [PMID: 31914351, 34551227].