Weinrib R, Fortuny J, Martinez D, Kollhorst B, Haug U, Kousholt A, Ehrenstein V, Iversen P, Mortensen J, Bosch D, Kuppen M, Pisa F, Vassilev Z. Drug utilisation of radium-223 under routine clinical practice (DIRECT) in Europe: a post-authorisation safety study. Oncol Ther. 2025 Sep;13(3):595-616. doi: 10.1007/s40487-025-00344-4

INTRODUCTION: Radium-223 is indicated for adults with metastatic castration-resistant prostate cancer (mCRPC) and symptomatic bone metastases, without visceral metastases, who progress after at least (≥) two lines of or are ineligible for other systemic therapies (besides luteinising hormone-releasing hormone analogues). Radium-223 is contraindicated in combination with abiraterone acetate and prednisone/prednisolone. Point 2 and the contraindication above were added to the 2018 European Medicines Agency (EMA) label. In the observational cohort study reported here, we evaluated compliance with the 2018 revised label.

METHODS: The proportion of patients with mCRPC who initiated radium-223 in the Netherlands, Germany and Denmark was analysed descriptively before (2013-2017) and after (2019-2020) the label change, allowing ≥ 6 months of follow-up. No a priori hypotheses were evaluated.

RESULTS: A total of 1070 patients were included in this observational cohort study (before/after the label change: Netherlands [243/53]; Germany [580/71]; Denmark [60/63]). Radium-223 use with abiraterone acetate or other systemic mCRPC therapies was limited and decreased after the label change in the Netherlands and Germany; in Denmark, combined use was not observed before the label change and was observed only rarely after the label change. After the label change, radium-223 use without ≥ 2 prior lines of systemic mCRPC therapy decreased in all countries, despite remaining relatively common in the Netherlands and Germany.

CONCLUSIONS: Radium-223 use in combination with abiraterone acetate or other systemic mCRPC therapies largely aligned with the 2018 EMA label change. However, after the label change, radium-223 use without ≥ 2 prior lines of systemic mCRPC therapy remained relatively common in the Netherlands and Germany, possibly because radium-223 was previously recommended as first-line treatment for frail patients, and doctors still may consider it for use in these cases. We could not assess patients' eligibility for other systemic mCRPC therapies; therefore, these findings may partly reflect radium-223 on-label use in patients with contraindications for other systemic therapies.