Potent, orally available, and highly selective inhibitor of 17,20-lyase (CYP17A1; IC50 value 19 nM and 48 nM for human and rat respectively) and of correlated androgen synthesis. TAK 700 exhibits no affinity for CYP11B 1and CYP3A4 (IC50 values >1000 nM and >10000 nM resp.), nor for other isoforms of the human CYP enzyme (IC50 values >14000 nM). When given orally to monkeys at a dose of 1 mg/kg, TAK 700 markedly reduced serum testosterone and DHEA at 5 h after administration. TAK 700 was selected for evaluation in patients in phase III clinical trials for the potential treatment of prostate cancer.