Combretastatin A-1 phosphate (OXi-4503) tetrasodium, a prodrug of Combretastatin A-1, is a tubulin-binding microtubule polymerization inhibitor that targets the colchicine-binding site. By inducing tubulin depolymerization, Combretastatin A-1 phosphate tetrasodium inhibits the Wnt/β-catenin pathway and leads to the deactivation of AKT. It possesses both anti-tumor and anti-vascular properties.

Combretastatin A-1 phosphate (72 h) inhibits the growth of various tumor cell lines in vitro, including HepG2, SMMC-7721, Hepa 1-6, LM-3, Bel-7402, Huh7, BGC-803, MDA-MB-231, MCF-7, A375, NCI-1975, CT-26, HT-29, A549 cells (IC 50 =9.2, 12.8, 32.9, 33.8, 38.4, 728.2, 12.2, 17.6, 46.0, 61.0, 256.3, 1075.0, 2082.0, 2247.0 nM, respectively)[2]. Combretastatin A-1 phosphate (1-10 nM; 24 h) induces apoptosis by microtubule depolymerization-induced AKT inactivation and the removal of GSK-3β inhibition in HepG2 cells[2]. Combretastatin A-1 phosphate (1-50?nM; 6 h) decreases the mitochondrial membrane potential (MMP) of HepG2 cells. Combretastatin A-1 shows dose-dependently ROS accumulation in HepG2 cells[2]. Western Blot Analysis[2]Cell Line: HepG2 cells Concentration: 1, 5, 10 nM Incubation Time: 24 hours Result: Significantly decreased Mcl-1 expression, but the Bcl-2 level was unchanged. Reduced p-GSK 3β (Ser9) without altering total GSK-3β protein levels, indicating an activation of GSK-3β. Reduced AKT phosphorylation on Ser473 without an obvious change in the total AKT protein levels.

Combretastatin A-1 phosphate (1-4?mg/kg; i.v. every other day for 4 weeks) significantly reduces the tumor volume in HepG2 subcutaneous xenograft model[2]. Combretastatin A-1 phosphate (2 mg/kg; every other day for 21 days) shows enhanced apoptosis in orthotopic hepatocellular carcinoma mouse model[2]. Animal Model: Male athymic BALB/c nu/nu mice (16-18 g; 4-6 weeks old) were inoculated with HepG2 cells[2]Dosage: 1, 2, 4?mg/kg Administration: I.v. every other day for 4 weeks Result: Resulted in a significant tumor volume reduction at the dose of 2?mg/kg or 4?mg/kg.