Symptomatic skeletal event (SSE) free survival is based on the following events: the use of external beam radiotherapy (EBRT) to relieve skeletal symptoms; the occurrence of new symptomatic pathological bone fractures (vertebral or nonvertebral); the occurrence of spinal cord compression; a tumor related orthopedic surgical intervention, and death. In this evaluation - comparison 1, SSE-FS following randomization is defined in ITT participants as the time from randomization to an SSE or death, whichever occurs first.

Intent-to-treat (ITT): All randomized participants. Data from Arm C are truncated at 7th dose date when pooling with Arm A, therefore Pooled Arm A+C included 261 participants.

In this evaluation - comparison 1, SSE-FS following randomization is defined in ITT participants as the time from randomization to an SSE or death, whichever occurs first.

Intent-to-treat (ITT): All randomized participants. Data from Arm C are truncated at 7th dose date when pooling with Arm A, therefore Pooled Arm A+C included 261 participants.

Symptomatic skeletal event (SSE) free survival is based on the following events: the use of external beam radiotherapy (EBRT) to relieve skeletal symptoms; the occurrence of new symptomatic pathological bone fractures (vertebral or nonvertebral); the occurrence of spinal cord compression; a tumor related orthopedic surgical intervention, and death. In this evaluation - Comparison 2, SSE-FS from 6th dose is defined in W24 participants as the time from Week 24 baseline (the 6th dose date) to an SSE or death, whichever occurs first.

Week 24 (W24): All ITT participants in Arm A (standard dose) and Arm C (extended dosing) treated with radium-223 dichloride and eligible for further treatment at W24 (i.e., 7th injection). All participants who received 6 doses from Arm A and participants who received >=6 doses from Arm C were included .

In this evaluation - Comparison 2, SSE-FS from 6th dose is defined in W24 participants as the time from Week 24 baseline (the 6th dose date) to an SSE or death, whichever occurs first.

Week 24 (W24)

Symptomatic skeletal event (SSE) free survival is based on the following events: the use of external beam radiotherapy (EBRT) to relieve skeletal symptoms; the occurrence of new symptomatic pathological bone fractures (vertebral or nonvertebral); the occurrence of spinal cord compression; a tumor related orthopedic surgical intervention, and death.

ITT

Symptomatic skeletal event (SSE) is defined as follows: The use of external beam radiotherapy (EBRT) to relieve skeletal symptoms; The occurrence of new symptomatic pathological bone fractures (vertebral or nonvertebral); The occurrence of spinal cord compression; A tumor related orthopedic surgical intervention.

ITT

Overall survival was defined as the time in days from the applicable start date to the date of death due to any cause. Participants who were still alive or who were lost to survival follow-up as of database cut-off date were to be censored at the last known alive date on or prior to database cut-off date.

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

Overall survival was defined as the time in days from the applicable start date to the date of death due to any cause. Participants who were still alive or who were lost to survival follow-up as of database cut-off date were to be censored at the last known alive date on or prior to database cut-off date.

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

Overall survival was defined as the time in days from the applicable start date to the date of death due to any cause. Participants who were still alive or who were lost to survival follow-up as of database cut-off date were to be censored at the last known alive date on or prior to database cut-off date.

Week 24 (W24)

Overall survival was defined as the time in days from the applicable start date to the date of death due to any cause. Participants who were still alive or who were lost to survival follow-up as of database cut-off date were to be censored at the last known alive date on or prior to database cut-off date.

Week 24 (W24)

Overall survival was defined as the time in days from the applicable start date to the date of death due to any cause. Participants who were still alive or who were lost to survival follow-up as of database cut-off date were to be censored at the last known alive date on or prior to database cut-off date.

ITT

Overall survival was defined as the time in days from the applicable start date to the date of death due to any cause. Participants who were still alive or who were lost to survival follow-up as of database cut-off date were to be censored at the last known alive date on or prior to database cut-off date.

ITT

Symptomatic skeletal event (SSE) is defined as follows: The use of external beam radiotherapy (EBRT) to relieve skeletal symptoms; The occurrence of new symptomatic pathological bone fractures (vertebral or nonvertebral); The occurrence of spinal cord compression; A tumor related orthopedic surgical intervention.

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

Time to first SSE is defined as the time in days from the applicable start date to the first SSE on or following the start date.

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

Symptomatic skeletal event (SSE) is defined as follows: The use of external beam radiotherapy (EBRT) to relieve skeletal symptoms; The occurrence of new symptomatic pathological bone fractures (vertebral or nonvertebral); The occurrence of spinal cord compression; A tumor related orthopedic surgical intervention.

Week 24 (W24)

Time to first SSE is defined as the time in days from the applicable start date to the first SSE on or following the start date.

Week 24 (W24)

Symptomatic skeletal event (SSE) is defined as follows: The use of external beam radiotherapy (EBRT) to relieve skeletal symptoms; The occurrence of new symptomatic pathological bone fractures (vertebral or nonvertebral); The occurrence of spinal cord compression; A tumor related orthopedic surgical intervention.

ITT

Time to first SSE is defined as the time in days from the applicable start date to the first SSE on or following the start date.

ITT

Radiological progression of soft tissue disease is determined according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 based on Magnetic resonance imaging (MRI) or computed tomography (CT) scans. Radiological progression of osseous disease is determined according to adapted PCWG2 criteria based on whole body technetium-99 bone scans. Radiological bone progression is determined if at least one of the following criteria is met: The first bone scan with ≥2 new lesions compared to baseline is observed <12 weeks from randomization and is confirmed by a second bone scan taken ≥6 weeks later showing ≥2 additional new lesions (a total of ≥4 new lesions compared to baseline); or The first bone scan with ≥2 new lesions compared to baseline is observed ≥12 weeks from randomization and the new lesions are verified on the next bone scan ≥6 weeks later (a total of ≥2 new lesions compared to baseline).

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

Radiological progression free survival is defined as the time in days from the applicable start date to the date of subsequent radiological disease progression or death from any cause (if death occurs before such progression). Participants not experiencing death or radiological disease progression as of database cut-off were censored at the last radiological disease progression assessment.

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

Radiological progression of soft tissue disease is determined according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 based on Magnetic resonance imaging (MRI) or Computed tomography (CT) scans. Radiological progression of osseous disease is determined according to adapted PCWG2 criteria based on whole body technetium-99 bone scans.

Baseline is randomization date

Radiological progression free survival is defined as the time in days from the applicable start date to the date of subsequent radiological disease progression or death from any cause (if death occurs before such progression). Participants not experiencing death or radiological disease progression as of database cut-off were censored at the last radiological disease progression assessment.

Baseline is randomization date

Radiological progression of soft tissue disease is determined according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 based on Magnetic resonance imaging (MRI) or Computed tomography (CT) scans. Radiological progression of osseous disease is determined according to adapted Prostate Cancer Clinical Trials Working Group 2 (PCWG2) criteria based on whole body technetium-99 bone scans.

ITT

Radiological progression free survival is defined as the time in days from the applicable start date to the date of subsequent radiological disease progression or death from any cause (if death occurs before such progression). Participants not experiencing death or radiological disease progression as of database cut-off were censored at the last radiological disease progression assessment.

ITT

Radiological progression of soft tissue disease is determined according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 based on Magnetic resonance imaging (MRI) or Computed tomography (CT) scans. Radiological progression of osseous disease is determined according to adapted Prostate Cancer Clinical Trials Working Group 2 (PCWG2) criteria based on whole body technetium-99 bone scans.

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

Time to radiological progression is defined as the time in days from the applicable start date to the date of subsequent radiological progression. Participants without radiological progression as of database cut-off date, whether or not surviving, were censored at the last radiological progression assessment.

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

Radiological progression free survival is defined as the time in days from the applicable start date to the date of subsequent radiological disease progression or death from any cause (if death occurs before such progression). Participants not experiencing death or radiological disease progression as of database cut-off were censored at the last radiological disease progression assessment.

Week 24 (W24)

Time to radiological progression is defined as the time in days from the applicable start date to the date of subsequent radiological progression. Participants without radiological progression as of database cut-off date, whether or not surviving, were censored at the last radiological progression assessment.

Week 24 (W24)

Radiological progression free survival is defined as the time in days from the applicable start date to the date of subsequent radiological disease progression or death from any cause (if death occurs before such progression). Participants not experiencing death or radiological disease progression as of database cut-off were censored at the last radiological disease progression assessment.

ITT

Time to radiological progression is defined as the time in days from the applicable start date to the date of subsequent radiological progression. Participants without radiological progression as of database cut-off date, whether or not surviving, were censored at the last radiological progression assessment.

ITT

Timepoint pain improvement rate is defined as the proportion of participants with a 30% and 2-point decrease in Worst pain score (WPS) from baseline over 2 consecutive assessment periods conducted at least 4 weeks apart among participants with a WPS score ≥ 4 at baseline.

ITT

Timepoint pain improvement rate is defined as the proportion of participants with a 30% and 2-point decrease in Worst pain score (WPS) from baseline over 2 consecutive assessment periods conducted at least 4 weeks apart among participants with a WPS score ≥ 4 at baseline.

Week 24 (W24)

Participants were divided in 3 groups according to baseline pain evaluation: asymptomatic subjects (WPS 0 to < 1 at baseline); mildly symptomatic subjects (WPS 1-3 at baseline); and symptomatic subjects with WPS > 3 and ≤ 7 at baseline). Pain progression was defined as the occurrence of a pain increase of 2 or more points in the average (i.e., average of 7-day assessments) "worst pain in 24 hours" score from baseline observed at 2 consecutive evaluations ≥ 4 weeks apart. Participants with insufficient applicable baseline assessments or without adequate post-baseline assessments were to be censored at the applicable baseline date.

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

The time to pain progression is defined for each applicable baseline for applicable participants as the time (in days) from the respective baseline until occurrence of the first post-baseline pain progression event.

ITT. Data from Arm C are truncated at 7th dose date when pooling with Arm A.

Pain progression is defined for each baseline in participants evaluable for pain progression at the applicable baseline, i.e., participants with a WPS of ≤ 7 at the respective baseline assessment.

Week 24 (W24)

The time to pain progression is defined for each applicable baseline for applicable participants as the time (in days) from the respective baseline until occurrence of the first post-baseline pain progression event.

Week 24 (W24)

Pain progression is defined for each baseline in participants evaluable for pain progression at the applicable baseline, i.e., participants with a WPS of ≤ 7 at the respective baseline assessment.

ITT

The time to pain progression is defined for each applicable baseline for applicable participants as the time (in days) from the respective baseline until occurrence of the first post-baseline pain progression event.

ITT

Treatment-emergent adverse events are events starting or worsening from the initiation of treatment until 30 days after the last administration of radium-223 dichloride. The intensity of an AE is classified according to the grades specified by the National Cancer Institute- Common Terminology Criteria for Adverse Events (NCI-CTCAE).

Safety Analysis Set

Analgesic use in this study were captured via two methods: Analgesic concomitant medication case report form, where the physician records the analgesic medication prescribed to manage pain; 24 hour analgesic consumption case report form, in which all analgesic medication taken in the last 24 hours.