The influence of VEGFR-2 blockade and focused ultrasound blood-brain barrier opening on the glioma-immune landscape.

BACKGROUND: Glioblastoma (GBM) is an aggressive brain cancer with limited treatment options and high recurrence rates. The blood-brain barrier (BBB) impedes therapeutic delivery for the brain, limiting systemic treatment efficacy. Focused ultrasound (FUS) combined with microbubbles (MBs) can transiently open the BBB (BBBO), enhancing drug delivery and modulating the tumor immune microenvironment (TME). However, the disorganized and leaky vasculature in GBM limits the effectiveness of FUS-mediated BBBO. Vascular normalization using antiangiogenic therapy may enhance both immune modulation and delivery. This study aimed to investigate whether vascular normalization via VEGFR-2 blockade with DC101, alone or in combination with FUS+MBs, improves TME remodeling in a murine GBM model. METHODS: CT2A glioma-bearing mice were treated with DC101, a VEGFR2 inhibitor, either alone or in combination with FUS+MBs. Tumor growth, survival, vessel permeability, immune cell profiling, and adhesion molecule expression were evaluated using immunohistochemistry, flow cytometry, and confocal microscopy. RESULTS: DC101 monotherapy significantly reduced tumor growth and prolonged survival. It reduced tumor vessel permeability and increased ICAM1 expression on CD31(+) endothelial cells, consistent with vascular normalization. DC101 also reduced FOXP3(+) regulatory T cells (Tregs) and increased the CD8/Treg ratio, indicating a more immunostimulatory TME. However, the addition of FUS+MBs in this normalized vascular environment did not further alter the immune landscape, suggesting a stable, quiescent TME. CONCLUSION: DC101-mediated vascular normalization beneficially remodels the GBM TME and creates a quiescent platform for supporting future FUS-based therapeutic delivery. This combinatorial strategy offers a promising approach to overcoming BBB-related barriers in glioma treatment.