Fig. 5.

Sunitinib reduces angiogenesis of intracranial U87MG tumors. Athymic mice bearing U87MG tumors were treated with an 80 mg/kg per day dose of sunitinib (schedule 5/2) and sacrificed 22 days after implantation. Brain sections 20 μm thick were subjected to von Willebrand factor immunohistochemistry and hematoxylin staining. (A) Representative photomicrographs from U87MG untreated (left) and sunitinib-treated (right) tumors, and accompanying graphs, show that sunitinib treatment produced 74% reductions in tumor microvessel density (18,267 ± 1,244 μm² vs. 4,702 ± 568 μm² per 10⁵-μm² tumor; p < 0.05). (B) Hematoxylin staining of sections shows that sunitinib treatment was associated with tumor necrosis (panel I vs. III) and decreases in U87MG proliferation, as demonstrated by reduced MIB-1 (Ki-67) immunostaining (panel II vs. IV).