Study in Japan and Ex-Japan to Characterize the Pharmacokinetic and Pharmacodynamic Response to Orteronel (TAK-700) in Chemotherapy-Naive Participants With Castration-Resistant Prostate Cancer

The drug being tested in this study is called orteronel. Orteronel is being tested to treat adult males who have adenocarcinoma of the prostate. This study will look at the pharmacokinetics (how the drug moves through the body) and pharmacodynamics (how the drug effects the body) in people who take orteronel in addition to prednisone. The study will enroll approximately 144 patients. Participants will be randomly assigned (by chance, like flipping a coin) to one of the eight treatment groups (4 in Japan, 4 in Ex-Japan) which will remain undisclosed to the participant and study doctor during the study (unless there is an urgent medical need). In Japan: Participants were randomized in a ratio of 2:1:2:1 * 200 mg orteronel or Placebo-matching orteronel \[(dummy inactive pill) - this is a tablet that looks like the study drug but has no active ingredient\] twice daily (BID) + prednisone * 300 mg orteronel, or Placebo-matching orteronel, BID + prednisone Ex-Japan Participants were randomized in a ratio of 2:1:2:1 * 200 mg orteronel or Placebo-matching orteronel, BID in Cycle 1 + prednisone * 400 mg orteronel, or Placebo-matching orteronel ,BID in Cycle 1 + Prednisone Participants initially randomized to placebo received 4 weeks of placebo and then 12 weeks of active treatment with orteronel then entered a follow-up period treatment period. Participants initially randomized to orteronel received 16 weeks of treatment then entered a follow-up treatment period. This multi-centre trial will be conducted worldwide. The overall time to participate in this study is approximately 3.2 years. Participants will make multiple visits to the clinic and a final visit 30 to 40 days after receiving their last dose of study drug for a follow-up assessment.