Zibotentan is a selective antagonist of the endothelin (ET) receptor type A (IC50s = 21 and >10,000 nM for human recombinant ETA and ETB, respectively). It inhibits growth of HEY, OVCA 433, SKOV3, and A2780 cells induced by endothelin 1 (ET-1; ) in vitro. Zibotentan reduces ET-1-induced expression of MMP-2, MMP-9, VEGF, COX-1 and COX-2, mediators of cell invasion and angiogenesis, in HEY cells. In vivo, zibotentan (10-50 mg/kg per day) reduces tumor growth in an HEY mouse xenograft model in a dose-dependent manner. Formulations containing zibotentan are under clinical investigation for the treatment of ovarian and castration-resistant prostate cancers.
