Peptide-Major Histocompatibility Complex (pMHC) (pMHC)

Peptide-Major Histocompatibility Complex (pMHC) molecules on malignant cells are a specialized class of therapeutic targets that allow the immune system to recognize intracellular tumor antigens. These complexes consist of a short peptide fragment, derived from the degradation of internal cellular proteins, bound to a Major Histocompatibility Complex (MHC) molecule—referred to as Human Leukocyte Antigen (HLA) in humans—and presented on the cell surface (Nature Reviews Drug Discovery, 2021). This presentation mechanism is crucial because it exposes the internal proteome of the cancer cell, including mutated neoantigens and overexpressed oncogenic proteins, to T-cells (Frontiers in Immunology, 2020). Therapeutic interventions targeting pMHCs include T-cell receptor (TCR) engineered T-cells, such as Afamitresgene autoleucel, and bispecific T-cell engagers like Tebentafusp (FDA, 2022; FDA, 2024). These drugs are designed to bind with high specificity to a particular peptide-HLA combination, triggering a potent cytotoxic immune response against the tumor (Journal of Hematology & Oncology, 2021). Unlike traditional monoclonal antibodies that target surface proteins, pMHC-targeting agents can address the vast majority of the proteome that remains inside the cell (Nature Reviews Drug Discovery, 2021). However, the efficacy of these treatments is limited to patients with specific HLA genotypes and is susceptible to tumor escape through HLA downregulation or loss of heterozygosity (Cancer Discovery, 2022). Safety remains a primary concern, as off-target cross-reactivity with similar peptides in healthy tissues can lead to severe adverse events, as seen in early clinical trials (Journal of Hematology & Oncology, 2021).

Other names

HLA-peptide complexMHC-restricted antigenTumor-associated pMHCMHC-peptide complexMHC-restricted tumor antigenpMHCMHC-restricted tumor-associated antigen

Binding of engineered T-cell receptors (TCRs) or TCR-mimetic antibodies to specific peptide-MHC complexes to trigger T-cell mediated cytotoxicity against malignant cells.