Tumor-associated antigen–derived peptide presented on HLA class I (pMHC-I)

Tumor-associated antigen (TAA)-derived peptides presented on HLA class I molecules are a specialized class of therapeutic targets that enable the immune system to recognize intracellular oncogenic proteins. These targets are formed when cellular proteins are processed into short peptides and loaded onto Human Leukocyte Antigen (HLA) class I molecules for display on the cell surface (Janeway's Immunobiology). This presentation allows CD8+ T cells to survey the internal proteome of a cell, identifying mutations or abnormally expressed proteins characteristic of malignancy (Nature Reviews Cancer, 2017). Modern immunotherapies, such as TCR-engineered T cells (TCR-T) and TCR-bispecific engagers, are designed to bind these specific peptide-HLA (pMHC) complexes with high affinity (FDA, 2024). Unlike traditional monoclonal antibodies that target surface proteins, pMHC-targeting agents can address the vast majority of the proteome, including transcription factors and intracellular signaling molecules (NEJM, 2021). However, the high specificity required poses significant challenges, as cross-reactivity with similar peptides in healthy tissues can lead to severe off-target toxicity (Journal for ImmunoTherapy of Cancer). Additionally, tumors may escape detection by downregulating HLA expression or through the loss of specific HLA alleles (Cancer Discovery). This target class represents a frontier in precision oncology, requiring both HLA matching and antigen verification for patient selection.

Other names

Peptide-MHC class I complexpMHC-IHLA-restricted tumor antigenTumor-specific peptide-HLA complexpMHC complex

Recognition of the specific peptide-HLA complex by engineered T-cell receptors (TCRs) or TCR-mimetic antibodies, which triggers the activation of cytotoxic T-lymphocytes and leads to the targeted lysis of the tumor cell.