As I have said before, the next big step in the clinical care of men with prostate cancer will be in not in the development of a new drug, but in our growing knowledge of how to sequence and combine our new drugs. Today’s post provides just one example of this new type of breakthrough we can look forward to in the near future.

In a recently released phase IIIb study of Radium-223 dichloride (Xofigo) that was given with concomitant medication, there was an improvement in overall survival (OS) in men with metastatic castration-resistant prostate cancer (mCRPC) who also had bone metastases.

The study evaluated data from 696 men with bone metastatic CRPC in an international expanded access program (EAP). The subject men received radium-223 and were also permitted to receive concomitant therapy, with 22% of those receiving concomitant therapy on abiraterone (Zytiga), 20% on denosumab, 18% on bisphosphonates, and 4% on enzalutamide (Xtandi). The study included both asymptomatic and symptomatic men.

At the time of the stud’s analysis the median OS was 16 months, and medium time to first symptomatic skeletal events (SSE) was 18 months. An ad-hock analysis found that OS was statistically significantly longer in those men who received concomitant denosumab and concomitant abiraterone. Grade 3/4 adverse events (AEs) were reported in 38% of patients, with 21% discontinuing radium-223 due to AEs.

The study was a follow-up to the ALSYMPCA trial, which compared the efficacy and safety of radium-223 with placebo in 921 men with mCRPC and symptomatic bone metastases. The study demonstrated an improvement in OS in those men who received radium-223 versus placebo. In the ALSYMPCA trial Xofigo also delivered an improvement in the median time to the first bone issues with 13.6 months and 8.4 months to first event with radium-223 versus placebo, respectively.

If you have multiple bone metastases you should speak with your doctor about combining Xofigo with another drug, perhaps with Zytiga.