Primary objective: To investigate the biodistribution, radiation dosimetry, and pharmacokinetics of two separate intravenous (IV) injections of Xofigo (100 kBq/kg body weight [b.w.] [=110 kBq/kg based on the 2015 National Institute of Standards and Technology standardization], 6 weeks apart).

Secondary objectives: To determine the safety of IV injections of Xofigo after two separate injections (6 weeks apart), to evaluate treatment response (antitumour effect in osteoblastic bone metastases) of Xofigo treatment consisting of two injections of activity 100 kBq/kg b.w. (=110 kBq/kg based on the 2015 National Institute of Standards and Technology standardization), 6 weeks apart and to evaluate long term radiation toxicity and to collect survival data at 6 and 12 months after the first injection

Inclusion Criteria:

• Histologically or cytologically confirmed adenocarcinoma of the prostate
• Hormone refractory with evidence of rising prostate-specific antigen (PSA): Subject must be maintained on androgen ablation therapy with luteinizing hormone-releasing hormone agonist or have undergone bilateral orchiectomy
• Serum testosterone level required to be ≤50 ng/dL
• Subjects who have received prior antiandrogen drug therapy: Flutamide, nilutamide, or cyproterone acetate must have stopped at least 4 weeks prior to study drug administration and progression, as defined by rising PSA as defined below, must have been demonstrated since cessation; bicalutamide must have stopped at least 6 weeks prior to study drug administration and progression, as defined by rising PSA as defined below, must have been demonstrated since cessation
• PSA progression: Progressive rise in PSA, defined as two consecutive increases in PSA documented over a previous reference value (measure 1). The first increase in PSA (measure 2) should occur at a minimum of 1 week from the reference value (measure 1). This increase in PSA should be confirmed (measure 3) after a minimum of 1 week. If the confirmatory PSA value (measure 3) is less than the previous value, the subject will still be eligible provided the next PSA measure (measure 4) is found to be greater than the second PSA value (measure 2)
• Skeletal metastases confirmed by bone scintigraphy within the last 6 weeks
• Performance status: Eastern Co-operative Oncology Group (ECOG) 0-2
• Life expectancy: ≥6 months
• Laboratory requirements: Neutrophil count ≥1.5 x 109/L, platelet count ≥100 x109/L, haemoglobin ≥95 g/L, total bilirubin level within normal institutional limits, aspartate aminotransferase and alanine aminotransferase ≤2.5 times upper institutional limit of the normal range, S Creatinine ≤1.5 times upper institutional limit of the normal range

Exclusion Criteria:

• Has received an investigational drug within 4 weeks prior to the administration of radium-223, or is scheduled to receive one during the treatment and post-treatment period
• Has received chemo-, immunotherapy, or external radiotherapy within the last 4 weeks prior to administration of study drug, or has not recovered from adverse events due to agents administered more than 4 weeks earlier
• More than one regimen of previous cytotoxic chemotherapy
• Has received prior hemibody external radiotherapy
• Has a need for immediate external radiotherapy
• Has received systemic radiotherapy with radium-223, strontium-89, samarium-153, rhenium-186 or rhenium-188 for the treatment of bony metastases within the last year prior to administration of study drug
• Has started treatment with bisphosphonates less than 3 months prior to administration of study drug. Patients are allowed to be on bisphosphonates provided patient is on a stable dose for >/= 12 weeks before administration of study drug
• Patients who are \