Study: NCT04666129

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Relugolix
Description: (Part 1 and Part 3) Relugolix will be administered orally as a single 360-milligram (mg) loading dose of 3 x 120-mg tablets, followed by a 120-mg dose (1 x 120-mg tablets), taken once daily at approximately the same time each day.~(Part 2) Relugolix will be administered orally as a single 360-milligram (mg) loading dose of 3 x 120-mg tablets, followed by a 240-mg dose (2 x 120-mg tablets), taken once daily at approximately the same time each day.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Relugolix
Description: (Part 1 and Part 3) Relugolix will be administered orally as a single 360-milligram (mg) loading dose of 3 x 120-mg tablets, followed by a 120-mg dose (1 x 120-mg tablets), taken once daily at approximately the same time each day.~(Part 2) Relugolix will be administered orally as a single 360-milligram (mg) loading dose of 3 x 120-mg tablets, followed by a 240-mg dose (2 x 120-mg tablets), taken once daily at approximately the same time each day.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Relugolix
Description: (Part 1 and Part 3) Relugolix will be administered orally as a single 360-milligram (mg) loading dose of 3 x 120-mg tablets, followed by a 120-mg dose (1 x 120-mg tablets), taken once daily at approximately the same time each day.~(Part 2) Relugolix will be administered orally as a single 360-milligram (mg) loading dose of 3 x 120-mg tablets, followed by a 240-mg dose (2 x 120-mg tablets), taken once daily at approximately the same time each day.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Abiraterone
Description: Abiraterone acetate (1000 mg \[2 x 500-mg tablets\]) or fine-particle abiraterone acetate (500 mg \[4 x 125-mg tablets\]) will be administered orally once daily.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Prednisone
Description: (Part 1 only) For participants with mCSPC, a 5-mg dose of prednisone will be administered orally once daily, and for participants with mCRPC, a 5-mg dose of prednisone will be administered orally twice daily.~(Part 3 only) Prednisone 5 mg can be administered orally twice daily but is not required.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Prednisone
Description: (Part 1 only) For participants with mCSPC, a 5-mg dose of prednisone will be administered orally once daily, and for participants with mCRPC, a 5-mg dose of prednisone will be administered orally twice daily.~(Part 3 only) Prednisone 5 mg can be administered orally twice daily but is not required.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Methylprednisolone
Description: For participants with mCRPC taking fine-particle abiraterone acetate, methylprednisolone 4 mg will be administered orally twice daily.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Apalutamide
Description: Apalutamide 240 mg (4 x 60-mg tablets) will be administered orally once daily.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Docetaxel
Description: Docetaxel 75 mg/m2 dose will be administered every 3 weeks as a 1-hour intravenous infusion.