Tumor-associated antigen-Major Histocompatibility Complex (TAA-MHC) (TAA-MHC)

The Tumor-associated antigen-Major Histocompatibility Complex (TAA-MHC) is a molecular assembly consisting of a tumor-derived peptide fragment bound within the groove of a Major Histocompatibility Complex (MHC) molecule, specifically Human Leukocyte Antigen (HLA) in humans. This complex serves as the primary signal for T-cell recognition, allowing the immune system to detect intracellular oncogenic transformations that are not visible as surface proteins (Nature Reviews Drug Discovery, 2022). In oncology, these complexes are targeted by TCR-based therapies, including TCR-engineered T-cells (TCR-T) like Afamitresgene autoleucel and bispecific molecules like Tebentafusp (FDA, 2022; FDA, 2024). These therapies are highly specific to both the peptide sequence and the patient's HLA genotype, necessitating precise patient screening for both the target antigen and the specific HLA allele. The biological significance of the TAA-MHC target lies in its ability to present a vast array of intracellular targets, including neoantigens and cancer-testis antigens, which are often more tumor-specific than traditional surface markers. However, the clinical application is challenged by potential cross-reactivity with similar peptides in normal tissues and the ability of tumors to evade detection by downregulating HLA expression (Journal of Hematology & Oncology, 2021).

Other names

pHLApMHCPeptide-HLA complexTumor-specific antigen-MHC complexNeoantigen-MHC complexPeptide-Major Histocompatibility Complex

Therapeutic agents such as TCR-engineered T-cells (TCR-T) or Immune mobilizing monoclonal T-cell receptors against cancer (ImmTACs) bind specifically to the peptide-MHC complex on the tumor cell surface. This binding mimics the natural T-cell receptor (TCR) interaction but often with significantly higher affinity, triggering the recruitment and activation of cytotoxic T-lymphocytes which release perforins and granzymes to induce tumor cell lysis (Hunter et al., 2023; FDA, 2024).