Human epidermal growth factor receptor 2-derived peptide–Major histocompatibility complex class II complex (HER2-peptide–MHC II)

The Human epidermal growth factor receptor 2 (HER2)-derived peptide–Major histocompatibility complex (MHC) class II complex is a molecular assembly consisting of a specific HER2 peptide fragment bound to an MHC class II molecule. This complex is primarily presented on the surface of antigen-presenting cells or tumor cells to be recognized by CD4+ helper T cells (Knutson et al., 2001, PMID: 11359824). Recognition by the T-cell receptor (TCR) triggers the activation of CD4+ T cells, which are essential for orchestrating a comprehensive immune response by providing help to CD8+ cytotoxic T cells and B cells (UniProt P04626). In oncology, this complex is a target for therapeutic vaccines such as AE37, which uses a modified HER2 peptide to enhance MHC class II loading and stimulate anti-tumor immunity (Mittendorf et al., 2012, PMID: 22843116). Additionally, adoptive cell therapies using TCR-engineered T cells are being developed to specifically target these pMHC II complexes on HER2-positive malignancies. The target's relevance is highly dependent on the patient's HLA genotype, as different MHC II alleles present different HER2-derived peptides. Therapeutic challenges include the potential for immune evasion through the downregulation of MHC molecules by the tumor and the risk of off-target effects in tissues with low-level HER2 expression. Overall, targeting the HER2-peptide–MHC II complex represents a sophisticated approach to cancer immunotherapy that leverages the helper arm of the adaptive immune system.

Other names

HER2/neu peptide-HLA class II complexHER2-MHC II complexpMHCII (HER2)ERBB2 peptide-MHC class II complex

Stimulation of CD4+ helper T cells through TCR recognition of the peptide-MHC II complex, leading to cytokine production and enhancement of the broader anti-tumor immune response.