The European Medicines Agency met from 5-8 March 2018. The interactions of different prostate cancer medications were discussed on the basis of study results. The focus was on the combination of radium 223 (Xofigo®) and abiraterone (Zytiga®).
Radium 223 (Xofigo®), which is used for prostate carcinomas with bone metastases, is suspected of increasing the risk of bone fractures and death when given in combination with abiraterone (Zytiga®) and prednisone/prednisolone.
In a clinical trial of patients with metastatic prostate cancer, 34.7% of patients treated with radium 223 in combination with abiraterone and prednisone/prednisolone have died so far. However, in the placebo group, which received only abiraterone and prednisone/prednisolone and no radium 223, only 28.2% have died. Fractures are also more frequent under the combination with radium 223 (26% versus 8.1%). The results are statistically significant.
In view of the severity of the events, the committee decided to issue a contraindication for combination therapy with abiraterone/prednisone/prednisolone with radium 223. Ongoing treatments should be discontinued!
As an additional warning, the European Commission for Medicinal Products points out that the safety and efficacy of radium 223 in combination with androgen receptor antagonists enzalutamide (Xtandi®) has also not been proven.
Treatment with radium 223 as monotherapy in castration-resistant prostate cancer with symptomatic bone metastases was not part of the Commission’s review.