Radium-223 Dichloride and Abiraterone Acetate Compared to Placebo and Abiraterone Acetate for Men With Cancer of the Prostate When Medical or Surgical Castration Does Not Work and When the Cancer Has Spread to the Bone, Has Not Been Treated With Chemotherapy and is Causing no or Only Mild Symptoms

Inclusion Criteria: * Histologically confirmed adenocarcinoma of the prostate * Male subjects of age ≥ 18 years * Prostate cancer progression documented by prostate specific antigen (PSA) according to the Prostate Cancer Working Group 2 (PCWG2) criteria or radiological progression according to Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1 * Two or more bone metastases on bone scan within 4 weeks prior to randomization with no lung, liver, other visceral and/or brain metastasis * Asymptomatic or mildly symptomatic prostate cancer * Subjects who received combined androgen blockade with an anti-androgen must have shown PSA progression after discontinuing the anti-androgen prior to enrollment * Maintenance of medical castration or surgical castration with testosterone less than 50 ng/dL (1.7nmol/L) * Eastern Cooperative Oncology Group performance status (ECOG PS) score 0 or 1 Exclusion Criteria: * Prior cytotoxic chemotherapy for the treatment of CRPC, including taxanes, mitoxantrone and estramustine * Any chronic medical condition requiring a higher dose of corticosteroid than 5 mg prednisone/prednisolone twice daily * Pathological finding consistent with small cell carcinoma of the prostate * History of visceral metastasis, or presence of visceral metastasis detected by screening imaging examinations * History of or known brain metastasis * Malignant lymphadenopathy exceeding 3 cm in short-axis diameter * Blood transfusion or erythropoietin stimulating a…