Tumor neoantigen-MHC class I complex (pMHC I complex)

The tumor neoantigen-MHC class I complex is a molecular assembly consisting of a mutated peptide (neoantigen) derived from tumor-specific somatic mutations and a Major Histocompatibility Complex (MHC) class I molecule (NIH, 2024). This complex is primarily displayed on the surface of tumor cells and antigen-presenting cells (APCs), such as dendritic cells, where it serves as the fundamental unit for recognition by CD8+ T-cell receptors (TCRs) (Assay Genie, 2024). On APCs, these complexes are often formed through cross-presentation of exogenous tumor antigens, a process essential for the priming and activation of naive T cells (Cancer Biomed, 2024). In the context of cancer, the presence of these complexes allows the immune system to distinguish malignant cells from healthy ones, as neoantigens are not typically subject to central tolerance (Scifiniti, 2024). Therapeutically, this complex is a high-value target for personalized cancer immunotherapies, including neoantigen vaccines, TCR-engineered T-cell (TCR-T) therapies, and TCR-like (TCR-mimetic) antibodies (NIH, 2025). Vaccines aim to induce the formation of these complexes on APCs to stimulate a robust anti-tumor T-cell response, while TCR-T and TCR-like antibodies directly bind to the complex on tumor cells to trigger cell death. Challenges in targeting this complex include the high degree of patient specificity (heterogeneity), the potential for immune escape through MHC downregulation, and the risk of off-target toxicity if the targeted neoantigen resembles a self-peptide (Cancer Biomed, 2025).

Other names

Peptide-MHC class I complexNeoantigen-HLA complexpMHC complexTumor-specific antigen-MHC complexpMHC I

The target functions as a ligand for T-cell receptors (TCRs). Drugs such as vaccines induce the formation of these complexes on antigen-presenting cells to prime T cells, while TCR-T therapies and TCR-like antibodies bind to the complex on tumor cells to induce direct T-cell mediated cytotoxicity.