5042 Background: Ra-223, a targeted alpha therapy, prolonged survival with good safety in metastatic castration-resistant prostate cancer (mCRPC) in the phase 3 ALSYMPCA trial. REASSURE will evaluate Ra-223 short- and long-term safety in routine clinical practice settings. This is the first planned interim analysis (median 7 mo observation). Methods: This global, prospective, single-arm, observational study enrolled pts with mCRPC with bone metastases (mets) for whom Ra-223 therapy was planned. Follow-up will continue up to 7 years after last Ra-223 dose. Results: 1106 pts (437 N. America, 665 Europe, 4 not recorded) enrolled from 2 Sep 2014 to 22 Sep 2016. Baseline data are available from 583 pts receiving 1st- (1L), 2nd- (2L), or ≥3rd-line (≥3L) Ra-223 for mCRPC(Table). The majority of pts (n=369, 63%) completed 5–6 doses (1L, 70%; 2L, 64%; ≥3L, 49%); median 6 doses (1L,6; 2L, 6; ≥3L, 4). Treatment-emergent drug-related AEs occurred in 215 pts (37%). Post-treatment grade 3/4 thrombocytopenia occurred in 14 pts (2.4%) and anemia in 45 (7.7%). Conclusions: In routine clinical practice, Ra-223 was associated with no short-term safety concerns and appeared to be used in pts with less advanced mCRPC than in ALSYMPCA. The majority of pts on 1L/2L Ra-223 therapy received 5–6 doses. Ra-223 was often used with abiraterone or enzalutamide, but not chemotherapy. The next interim analysis in 2019 will report long-term safety and outcomes on all pts. Clinical trial information: NCT02141438. [Table: see text]
MP52-14 THE EFFECTIVENESS AND SAFETY OF CABAZITAXEL (CBZ) IN PATIENTS WITH METASTATIC CASTRATION-RESISTANT PROSTATE CANCER (MCRPC) IN ROUTINE CLINICAL PRACTICE: RESULTS OF A PROSPECTIVE OBSERVATIONAL STUDY (CAPRISTANA)