Abstract
Glioblastoma (GBM) is characterized by aberrant neovascularization and angiogenesis. Bevacizumab (Avastin), a monoclonal antibody targeting vascular endothelial growth factor (VEGF), is clinically used with chemotherapy for patients with GBM, yet its impact on the tumor immune microenvironment remains poorly understood. Transcriptomic profiling of matched pre- and post-treatment tumors from patients with recurrent GBM treated with bevacizumab plus the topoisomerase inhibitor irinotecan revealed significant immune reprogramming in responders, with post-treatment tumors displaying features indicative of tertiary lymphoid structure (TLS) formation and enhanced antitumor immunity. In preclinical orthotopic glioma models, combining αVEGF therapy with intratumoral epidermal growth factor receptor (EGFR)-targeted cytotoxic therapy and αCD40 immunotherapy normalized the tumor vasculature, promoted lymphatic vessel growth, induced tumor cell killing, increased intratumoral T cells, plasma cells, germinal center B cells, and antigen-presenting and tissue-repair-associated macrophages, while reducing immunosuppression and supporting mature TLS formation with an antitumor immune phenotype. Functionally, the tumor-, immune-, and vascular-targeted combination therapy significantly improved tumor control, extended survival, and induced durable antitumor memory in glioma models. Collectively, these results identify VEGF as a central regulator of the vascular-immune axis during cytotoxic EGFR+αCD40 therapy in GBM and provide a strong rationale for combining vascular-, tumor-, and immune-targeted approaches to overcome therapeutic resistance and improve outcomes for patients with GBM.