Melanoma-associated antigen A family peptide–HLA class I complex (MAGE-A–HLA-I complex)

The MAGE-A family–derived peptide–HLA class I complex is a molecular assembly consisting of a specific peptide fragment from the Melanoma-associated antigen A (MAGE-A) protein family bound to a Human Leukocyte Antigen (HLA) class I molecule on the cell surface. MAGE-A proteins are classified as cancer-testis antigens (CTAs), which are typically expressed only in the germ cells of the testis and placenta—tissues that lack HLA expression and are thus protected from T-cell recognition (PMID: 25103341). In many types of cancer, these genes are aberrantly reactivated, resulting in the presentation of MAGE-A peptides to the immune system, making the complex a highly specific tumor-associated target. Therapeutic strategies targeting this complex include engineered T-cell receptor (TCR-T) therapies and bispecific T-cell engagers designed to recognize the unique peptide-HLA conformation. For example, afamitresgene autoleucel targets the MAGE-A4 peptide presented by HLA-A*02 and has demonstrated clinical efficacy in treating synovial sarcoma (PMID: 38537582). A significant challenge in targeting this complex is ensuring high specificity to avoid cross-reactivity with similar peptides in vital organs, as seen in historical trials where MAGE-A3-targeted T-cells cross-reacted with the protein titin in cardiac tissue, leading to severe adverse events (PMID: 23943121).

Other names

MAGE-A peptide-MHC complexMAGE-A/HLA complexMAGE-A pMHCCancer-testis antigen peptide-HLA complexMAGE-A antigen-HLA complex

T-cell receptor (TCR) mediated recognition of the peptide-HLA complex leading to T-cell activation, cytokine release, and cytotoxic lysis of the target tumor cell.