Neoantigen-MHC class II complex (NeoAg-MHC II)

The neoantigen-MHC class II complex is a molecular assembly consisting of a tumor-specific mutated peptide (neoantigen) bound to a Major Histocompatibility Complex (MHC) class II molecule (Alspach et al., Nature, 2019). This complex is primarily presented on the surface of professional antigen-presenting cells (APCs) or certain MHC II-positive tumor cells, acting as the specific ligand for the T-cell receptor (TCR) of CD4+ helper T cells (Sahin et al., Nature, 2017). Recognition of this complex is a critical step in the orchestration of the adaptive immune response against cancer, leading to the activation of CD4+ T cells (Ott et al., Nature, 2017). Activated CD4+ T cells provide essential help for CD8+ cytotoxic T cells and can also exert direct anti-tumor effector functions through cytokine secretion or direct lysis (Zanetti, Nature Reviews Immunology, 2015). Therapeutic strategies targeting this interaction include personalized neoantigen vaccines, such as mRNA-4157 and BNT122, designed to elicit these T-cell responses (Moderna; BioNTech). Additionally, adoptive cell therapies (ACT) use tumor-infiltrating lymphocytes or engineered TCRs to directly recognize these complexes (Rosenberg et al., Science, 2014). The specificity of this interaction is key to minimizing off-target effects, as neoantigens are absent from healthy tissues. However, challenges remain, including the downregulation of MHC molecules by tumors to evade immune detection (Garrido et al., Cancer Immunology, Immunotherapy, 2016). Monitoring MHC II expression and neoantigen load serves as a vital biomarker strategy for patient selection in these therapies.

Other names

Neoepitope-MHC class II complexTumor-specific antigen-MHC II complexNeoantigen-HLA class II complexMHC II-restricted tumor neoantigen

Vaccines induce the formation of neoantigen-MHC II complexes on antigen-presenting cells to activate CD4+ T cells, while adoptive therapies provide T cells that recognize these complexes to trigger anti-tumor immunity (Sahin et al., Nature, 2017; Rosenberg et al., Science, 2014).