Stryker Central Nervous System Tumor Award - Modulation of Bioenergetics and Immunosuppression in Myeloid-Derived Suppressor Cells by Targeting the NRP2:VEGF Axis in Glioblastoma

Introduction: Efforts to adapt immunotherapies from other cancers to glioblastoma (GBM) are limited by its unique tumor microenvironment (TME), which is rich in immunosuppressive myeloid-derived suppressor cells (MDSCs) and hypoxic regions driven by VEGF-mediated angiogenesis. Neuropilin 2 (NRP2), a VEGF-activated receptor associated with poor prognosis in GBM, remains understudied in its immunomodulatory role. This study aims to examine the impact of NRP2 signaling on MDSC bioenergetics and their resultant immunosuppressive function in GBM.

Methods: Using single-cell RNA sequencing, we analyzed NRP2 expression in primary and recurrent human GBM samples. Hypoxia chambers were used to recapitulate the hypoxic environment of the GBM TME in vitro. Using monoclonal antibodies against NRP2, flow cytometry assessed how this pathway affected the immunophenotype of MDSCs, while the Seahorse XF assay measured the effect of NRP2 blockade on myeloid cell bioenergetics. A syngeneic GBM mouse model (CT-2A) was used to evaluate NRP2 blockade in the TME and its therapeutic efficacy in vivo.

Results: NRP2 is upregulated across primary and recurrent GBM cells as well as infiltrating MDSCs. Blocking NRP2 in hypoxic conditions shifted myeloid cells towards an anti-tumoral phenotype with upregulation of CD86 and MHCII expression. This decrease in immunosuppression was linked with rescue of mitochondrial function and augmented oxidative phosphorylation even within hypoxic environments. In mice, NRP2 blockade decreased MDSC infiltration into the TME and robustly extended median overall survival compared to other conventional immunotherapeutic strategies such as anti-PD-1 and STING agonists (P < 0.001).

Conclusion : NRP2 blockade reverses MDSC-mediated immunosuppression in the GBM TME and enhances anti-tumoral myeloid cell function with restoration of mitochondrial oxidative phosphorylation. This directly translates to improved survival in preclinical models. Given the distinct features of GBM compared to other cancers, therapeutic targets such as NRP2 that are specifically upregulated in the hypoxic GBM TME hold promise for developing novel and effective treatments.