Investigating the immunological effect of MYCN depletion in MYCN-amplified neuroblastoma 9167

Abstract Description Neuroblastoma, a pediatric cancer with poor responsiveness to immune checkpoint inhibitors, is characterized by low HLA expression, low tumor mutation burden, and low NK- and T-cell infiltration, especially in MYCN-amplified tumors. MYCN is linked to these immunologically cold traits, but its role in shaping the tumor-immune microenvironment (TIME) and immune responses remains poorly understood. We evaluated the efficacy of MYCi975, a MYCN-MAX dimerization disrupter, on MYCN-amplified neuroblastoma cell viability and MYCN target gene expression, and investigated the impact of MYCN depletion on regulating genes involved in innate and adaptive immunity. MYCi975 induced MYCN degradation, reducing viability and transcriptional activity. Flow cytometry revealed upregulation of death receptor 5 (DR5) and HLA-G, but no changes in other NK- or T-cell ligands or classical HLA proteins. This upregulation appeared specific to MYCN depletion, as it was absent in cells treated with doxorubicin or etoposide. MYCi975 also enhanced NK-cell mediated killing of MYCN-amplified cells in the presence of dinutuximab, an FDA-approved anti-GD2 monoclonal antibody for high-risk neuroblastoma, and reduced secretion of the immunosuppressive cytokine IGFBP-2. These findings reveal a mechanism by which MYCN influences anti-tumor immunity and suggest a broader role in TIME modulation, providing a foundation for exploring the therapeutic potential of HLA-G and DR5 co-upregulation with MYCN targeting. Funding Sources This work was funded by NIH grant U54 CA232568, NIH grant R5 CA220500 and the Alex’s Lemonade Stand Foundation. Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)