Combination of anti-angiogenic therapy with CSF1R inhibition decreases proliferation in RAS-driven GBM but does not improve survival outcomes. (A) Representative images of PDGFB- and RAS-driven tumors stained for CD31. Scale 100 µM. (B) Vessel density assayed by CD31 staining in PDGFB- and RAS-driven tumors by Angiotool (n = 4 samples/group, ***P < .001). (C) Representative images of CD31+ vessels from Ras-driven tumors treated with vehicle or PLX3397, scale 100 µM. Vessel area measured by Angiotool (ns, not significant). (D) Kaplan-Meier survival curve of mice with RAS-driven tumors treated with cediranib (6 mg/kg daily), vehicle, or the combination of cediranib with PLX3397 (100 mg/kg daily). (E) Representative tissue histology of tumors treated with vehicle, PLX3397, cediranib, or combination therapy. Scale: middle (1 mm) and lower panels (300 µM). (F) Quantification of tumor area fraction for tumors receiving vehicle, PLX3397, cediranib, or combination therapy (n = 3 tumors/group). **P < .01, 1-way ANOVA with multiple comparisons. ns, not significant. (G–H) Left: Representative images of CD31+ blood vessels (G) and p-H3+ cells (H) in endpoint RAS-driven tumors. Scale 100 µM. Right: Quantification of label+ cells in all treatment groups (n = 3 mice/group). **P < .01, ***P < .001, 1-way ANOVA with multiple comparisons. ns, not significant. Abbreviations: CSF1R, colony-stimulating factor 1 receptor; GBM, glioblastoma; PDGFB, platelet-derived growth factor subunit B.