Abstract
Glioblastoma (GBM) remains one of the most aggressive and treatment-resistant cancers, in large part due to the tightly regulated blood-brain barrier (BBB) and the immunosuppressive tumor microenvironment (TME). Focused ultrasound (FUS), when combined with intravenously administered microbubbles (MBs), provides a noninvasive and targeted way to temporarily disrupt the BBB, improving the potential for therapeutic delivery and immunomodulation. Yet, how FUS affects tumor vasculature and immune responses in GBM remains poorly understood. This dissertation examines how distinct vascular contexts—including VEGFR-2 inhibition, which reduces angiogenesis and stabilizes the BBB, and a physiologically relevant model of GBM-driven BBB breakdown—modulate the response to FUS and collectively influence the glioma-immune landscape. In the first set of studies, VEGFR-2 inhibition using DC101 was evaluated in the orthotopic CT2A-luc glioma model to assess changes in vascular structure and immune composition, both with and without FUS. Pre-treatment with DC101 decreased BBB/BTB permeability, reduced vessel density, and increased vessel area, consistent with transient vascular modulation. It also improved tumor growth control and increased the ratio of CD4 and CD8 T cells to regulatory T cells, reflecting a more favorable immune environment. While adding FUS did not further augment immune activation, it established a more stable vascular state that could support future combination therapies. The second study used a genetically engineered mouse model (GEMM) of GBM (3X CRISPR) to characterize the immune and vascular responses to FUS-mediated BBB disruption in an immunocompetent and genetically relevant setting. In this context, FUS induced modest but distinct immune changes compared with orthotopic tumors, highlighting how tumor origin and immune familiarity influence the overall response. Together, these studies shed new light on how vascular modulation and FUS-mediated BBB opening intersect to influence immune outcomes in GBM. The findings help clarify the biological context in which FUS operates and provide a foundation for designing next-generation therapeutic strategies that integrate vascular modulation, immune activation, and precision drug delivery to treat GBM.
