T cell receptor–Major Histocompatibility Complex–peptide complex (TCR-pMHC) (TCR-pMHC)

The T cell receptor–Major Histocompatibility Complex–peptide (TCR-pMHC) complex is the fundamental unit of adaptive immune recognition, consisting of a T cell receptor (TCR) binding to a peptide antigen presented by a Major Histocompatibility Complex (MHC) molecule [Janeway's Immunobiology, 2016]. In oncology, this complex typically involves tumor-associated antigens or neoantigens presented by MHC Class I or Class II, serving as a specific marker for malignant cells [The Lancet, 2024]. Therapeutic strategies such as TCR-engineered T cell (TCR-T) therapies and bispecific T-cell engagers (e.g., ImmTACs) are designed to target these complexes with high affinity to induce potent anti-tumor responses [NEJM, 2021]. These therapies, including the FDA-approved tebentafusp and afamitresgene autoleucel, redirect T cells to recognize and eliminate cells displaying the target pMHC [NEJM, 2021; The Lancet, 2024]. However, the approach is limited by the requirement for specific patient HLA types and the risk of off-target toxicity if the TCR cross-reacts with similar peptides on healthy tissues [Science Translational Medicine, 2018]. Successful targeting requires precise selection of both the peptide antigen and the restricting HLA allele to ensure safety and efficacy.

Other names

TCR-MHC-peptide complexTCR-antigen-MHC complexpMHC-TCR complexPeptide-MHC-TCR complexT cell receptor–MHC class I/II–tumor antigen complex

Therapeutic agents targeting this complex function by either providing T cells with an engineered TCR (TCR-T therapy) or using bispecific molecules (ImmTACs) to bridge the tumor-presented peptide-MHC complex to the CD3 receptor on endogenous T cells, thereby inducing targeted cytotoxicity [NEJM, 2021; The Lancet, 2024].