Melanoma-associated peptide-MHC complex (pMHC)

Melanoma-associated peptide antigens presented on MHC (Major Histocompatibility Complex) are a class of therapeutic targets consisting of short peptide fragments derived from intracellular melanoma proteins—such as gp100, MART-1, and the MAGE family—displayed on the cell surface by MHC molecules (nih.gov, 2022). These complexes are essential for the recognition of cancer cells by the cellular immune system, particularly cytotoxic T lymphocytes (CTLs), allowing the immune system to target intracellular proteins that are otherwise inaccessible to traditional antibody-based therapies (pnas.org, 2002). Therapeutic strategies targeting these complexes include bispecific T-cell engagers like tebentafusp, which targets a gp100-derived peptide on HLA-A*02:01, and TCR-engineered T-cell (TCR-T) therapies such as afamitresgene autoleucel (patsnap.com, 2024; nih.gov, 2023). These treatments work by redirecting T cells to form an immune synapse with the melanoma cell, leading to the release of perforin and granzymes and subsequent tumor cell apoptosis (patsnap.com, 2024). A significant challenge in targeting these antigens is HLA restriction, as therapies are often specific to a single HLA allele, such as HLA-A*02:01, limiting the eligible patient population (nih.gov, 2022). Furthermore, safety concerns include on-target, off-tumor toxicities, such as skin rash or uveitis, which occur when the targeted antigen is also expressed in healthy melanocytes (nih.gov, 2022; clinicaltrials.gov, 2015).

Other names

Melanoma-associated peptide antigens presented on MHCMelanoma-associated antigen (MAA)Tumor-associated antigen (TAA) in melanomaPeptide-HLA complexMelanoma-specific antigenpMHC complex

Drugs targeting these complexes typically employ T-cell redirection, where a bispecific molecule or an engineered T-cell receptor (TCR) binds the specific peptide-MHC complex on the tumor cell surface and simultaneously engages the CD3 complex on T cells, leading to T-cell activation, immune synapse formation, and the release of cytotoxic granules (perforin and granzymes) that induce apoptosis in the target melanoma cell (patsnap.com, 2024; nih.gov, 2023).