T cell receptor recognizing tumor antigenic peptide–MHC class I complex (TCR-pMHC-I)

The T cell receptor (TCR) recognizing tumor antigenic peptide–MHC class I complex is the fundamental unit of recognition for CD8+ T cells in the anti-tumor immune response. This complex consists of a heterodimeric TCR on a T cell that specifically binds to a processed tumor-derived peptide fragment presented within the groove of a Major Histocompatibility Complex (MHC) Class I molecule on the surface of a cancer cell (Janeway's Immunobiology, 2017). This interaction triggers a signaling cascade through the CD3 complex, resulting in T cell proliferation and the secretion of pro-inflammatory cytokines. Ultimately, this leads to the directed lysis of the tumor cell via the release of cytotoxic molecules like perforin and granzymes. In oncology, this mechanism is leveraged by TCR-engineered T-cell (TCR-T) therapies, where patient cells are modified to express high-affinity TCRs against specific tumor antigens like NY-ESO-1 or MAGE-A4 (Nature Reviews Drug Discovery, 2021). Additionally, soluble TCR-bispecific molecules like Tebentafusp use this recognition to bridge T cells to tumor cells, particularly in cancers with low mutational burdens. A major challenge in targeting this complex is ensuring high specificity to avoid cross-reactivity with similar peptides in healthy tissues, which can lead to severe toxicities (Blood, 2013).

Other names

T-cell receptorTCRTumor-specific T-cell receptorpMHC-I-specific TCRAntigen-specific T-cell receptorTCR-peptide-HLA complex

Drugs targeting this complex primarily function through two modalities: adoptive cell therapy (TCR-T) and soluble TCR-bispecifics. TCR-T therapy involves the genetic modification of a patient's own T cells to express a TCR with high affinity for a specific tumor-associated peptide-MHC complex, enabling direct recognition and killing of cancer cells (Adaptimmune, 2024). Soluble TCR-bispecific molecules, such as Immune Mobilizing Monoclonal TCRs Against Cancer (ImmTACs), consist of a high-affinity TCR domain fused to an anti-CD3 scFv, which recruits and activates any nearby T cell to attack the tumor cell presenting the specific pMHC (Immunocore, 2022).