Human epidermal growth factor receptor 2 peptide-MHC class I complex (HER2-pMHC-I)

The Human epidermal growth factor receptor 2 (HER2) peptide-MHC class I complex is a molecular assembly consisting of a specific peptide fragment derived from the HER2 protein bound within the groove of a Major Histocompatibility Complex (MHC) class I molecule, typically HLA-A2. This complex is presented on the surface of both healthy cells (at low levels) and overexpressing tumor cells, serving as the primary ligand for the T-cell receptors (TCRs) of CD8+ cytotoxic T lymphocytes. In the context of oncology, this complex is the fundamental target for cancer vaccines and TCR-based immunotherapies, which aim to prime the immune system to recognize these specific signatures on malignant cells. When a CD8+ T cell successfully binds to the HER2-pMHC-I complex via its TCR and receives necessary co-stimulatory signals, it triggers a cytotoxic response involving the release of perforins and granzymes, leading to the targeted destruction of the HER2-positive cell. Therapeutic strategies such as the E75 vaccine (Nelipepimut-S) utilize specific immunogenic peptides to increase the frequency of these circulating HER2-specific CD8+ T cells. While highly specific, the efficacy of targeting this complex can be limited by tumor-mediated downregulation of MHC molecules or the development of immune tolerance within the tumor microenvironment.

Other names

HER2 peptide-HLA complexERBB2 peptide-MHC class I complexNeu peptide-MHC complexHER2/neu MHC-I complexE75-HLA-A2 complex

Vaccines containing HER2-derived peptides (e.g., E75) are processed and presented by MHC class I molecules on the surface of cells. These HER2-pMHC-I complexes are then recognized by the T-cell receptors (TCRs) of CD8+ cytotoxic T lymphocytes, leading to the activation, proliferation, and recruitment of these T cells to recognize and lyse HER2-expressing tumor cells.