Melanoma-associated antigen 3 peptide-MHC class I complex (MAGE-A3-pMHC)

MAGE-A3 (Melanoma-associated antigen 3) is a prominent member of the cancer-testis antigen (CTA) family, characterized by its restricted expression in immune-privileged germ cells and its aberrant upregulation in various cancers (UniProt Consortium, 2024). The therapeutic target is specifically the processed MAGE-A3 peptide (such as EVDPIGHLY or KVAELVHFL) presented by Major Histocompatibility Complex (MHC) class I molecules, most commonly HLA-A*01 or HLA-A*02, on the surface of malignant cells (Morgan et al., 2013). This peptide-MHC (pMHC) complex allows the immune system to distinguish tumor cells from normal somatic cells, which do not express MAGE-A3. Therapeutic interventions, including TCR-engineered T-cells (TCR-T) and bispecific T-cell engagers, are designed to recognize this specific pMHC to induce targeted cell lysis. Despite its potential, targeting this complex has historically encountered significant safety hurdles, most notably lethal off-target cross-reactivity with MAGE-A12 in the central nervous system and the muscle protein Titin in the heart (Linette et al., 2013; Morgan et al., 2013). Consequently, modern drug development focuses on enhancing the specificity of TCRs to avoid these life-threatening toxicities while maintaining high affinity for the MAGE-A3-pMHC complex.

Other names

MAGE-A3/HLA complexMAGE-A3 peptide-HLA-A1 complexMAGE-A3 peptide-HLA-A2 complexMAGE3-pMHCAntigenic peptide MAGE-A3 presented by HLA-A1

T-cell receptor (TCR) mediated recognition of the peptide-MHC complex leading to T-cell activation and directed cytotoxicity against tumor cells.