Background: The ALSYMPCA study (Parker, NEJM, 2013) was the basis for regulatory approval of Ra-223 for the treatment of castrate-resistant prostate cancer (CRPC) patients (pts) with symptomatic bone metastases. The aim of this prospective EAP was to monitor acute and long-term safety of Ra-223. Pt profiles and findings in the EAP setting are presented. Methods: In the EAP, CRPC pts with symptomatic bone metastases who either received or were not eligible for docetaxel received Ra-223 50 kBq/kg by injection q4wks for 6 cycles. Primary endpts: ECOG PS, symptomatic skeletal-related events (SSE), treatment-emergent adverse events [TEAEs], routine laboratory tests including PSA. Exploratory endpts: overall survival (OS), SSE rates, changes in total ALP (tALP)/PSA responses, time to tALP normalization, and to tALP and PSA progression. Descriptive statistics were used. Results: 184 pts entered treatment; baseline characteristics were similar as seen in ALSYMPCA (N=600) (exceptions in table); 67% had total ALP <220 U/L and 47% mild/moderate pain. 81/184 (44%) received all 6 injections; 26 (14%) had a dose interruption/delay, 18 due to AEs. Median OS was 17m (50/184; 27% pts). TEAEs occurring at ≥10% were anemia, fatigue, diarrhea, and nausea. The most common Grade 3/4 hematologic TEAE was anemia (11%). Majority of pts had no change in ECOG PS within each trt cycle. 19 (10%) pts had an SSE, 13 received EBRT for bone pain. 33% of pts had a ≥30% confirmed ALP decline from baseline and 16% had a ≥50% decline. Median time to ALP progression was not reached. Median time to PSA progression was 4m and 6% had a confirmed PSA response. Conclusions: In heavily pretreated patients with CRPC and bone metastases and in an EAP setting, Ra-223 was well tolerated with no new safety concerns and a positive effect on efficacy parameters. Clinical trial information: NCT01516762