A tubulin polymerization inhibitor; binds to the colchicine binding site on β-tubulin (Ki = 3.3 μM); inhibits tubulin polymerization in a concentration-dependent manner; inhibits growth of 26 human tumor cell lines (IC50s = 0.06-0.08 μg/ml); induces tumor regression in NB-1382 neuroblastoma, IRS56 rhabdomyosarcoma, and KT-6 Wilms mouse xenograft models at 100 mg/kg; induces tumor endothelial cell retraction and reduces tumor perfusion in a 9L rat glioma subcutaneous tumor model