Tumor-associated antigen-Major Histocompatibility Complex-T-cell receptor complex (TAA-MHC-TCR complex)

The MHC class I/II–presented tumor-associated antigen (TAA) complex interacting with the T-cell receptor (TCR) is the central structural unit of the immunological synapse required for T-cell-mediated anti-tumor immunity (Abbas et al., Cellular and Molecular Immunology, 2021). This complex forms when a T-cell receptor recognizes a specific peptide fragment, derived from a tumor-associated protein, that is displayed on the cell surface by Major Histocompatibility Complex (MHC) molecules (Janeway et al., Immunobiology, 2016). For MHC Class I, the interaction typically involves CD8+ cytotoxic T cells, while MHC Class II interactions involve CD4+ helper T cells. This recognition event triggers intracellular signaling pathways that lead to T-cell activation, cytokine production, and the direct lysis of the tumor cell. Modern immunotherapies, such as TCR-engineered T-cells (TCR-T) and bispecific T-cell engagers like Tebentafusp, are designed to specifically bind these pMHC complexes to bypass natural immune tolerance (Nathan et al., NEJM, 2021). The therapeutic efficacy of targeting this complex depends heavily on the patient's HLA genotype and the high-fidelity expression of the target antigen on tumor cells (Hong et al., Lancet, 2024). However, the high sensitivity of the TCR means that even minor cross-reactivity with similar peptides in healthy tissues can lead to severe off-target toxicities (Linette et al., Blood, 2013).

Other names

pMHC-TCR complexPeptide-MHC-TCR complexAntigen-HLA-TCR complexTumor antigen-MHC-TCR synapse

T-cell redirection and activation via the formation of a synthetic or enhanced immunological synapse between the effector T-cell and the tumor cell.