Patient characteristics and safety of radium-223 dichloride in Taiwan: Analysis of realworld clinical practice.

119 Background: Bone metastases commonly develop in patients with metastatic castration-resistant prostate cancer (mCRPC), leading to poor clinical outcomes. Radium-223 (Ra-223) is a bone-targeting radiopharmaceutical that has been shown to improve the overall survival of these patients. Here, we present data on the safety and effectiveness of Ra-223 in patients with mCRPC and symptomatic bone metastases under routine clinical practice in Taiwan. Methods: This prospective, multicenter, single-arm, non-interventional observational study enrolled patients with mCRPC and symptomatic bone metastases. A total of 224 patients were included from July 2020 to January 2022. The patients received Ra-223 (55 kBq/kg of body weight) once every 4 weeks for a maximum of 6 intravenous injections. An exploratory subgroup analysis was conducted in patients who received Ra-223 either as a first-line, second-line or third-line. This first interim analysis of the study assessed the clinical outcomes observed during 6 months of Ra-223 treatment and 1 month after the final or last tolerated injection. Results: The dataset up until September 2021 (n = 104) was available for analysis. Of the 104 patients, 69 (66.3%) received 5–6 injections of Ra-223 while 35 (33.7%) received 1–4 injections. Sixty percent of enrolled patients were chemotherapy-naive. Furthermore, 22 (21.2%), 43 (41.3%) and 39 (37.5%) patients received Ra-223 as a first-, second- or third-line therapy, respectively; 16 (72.7%), 27 (62.8%) and 26 (66.7%) patients in these subgroups received 5–6 injections of Ra-223, respectively. The incidence of any study drug-related treatment-emergent adverse events (TEAEs), hematologic TEAEs and all fracture events were 10.6%, 9.6% and 1.9%, respectively. When compared with the other subgroups, patients on first-line Ra-223 therapy had lower incidences of any drug-related AEs and discontinuation of therapy owing to AEs. In addition, there was a trend observed that better PSA control occurred in patient population using Ra-223 as mCRPC first-line treatment. Conclusions: The study data showed that under routine clinical practice in Taiwan, the rate of Ra-223-associated AEs were low and no new safety concerns were identified with this therapy. First-line Ra-223 therapy was more likely associated with fewer TEAEs and higher rates of completion with the 6-injection course of therapy. A follow-up observation of up to 2 years after the initial injection is on-going. Clinical trial information: NCT04232761 .