Radium-223 (Xofigo) with concurrent abiraterone or enzalutamide: predictive biomarkers of improved overall survival in a clinically advanced cohort.

Purpose: Radium-223 (Xofigo) is the first therapy with bone tropism for metastatic castrate-resistant prostate cancer (mCRPC) that has been shown to improve overall survival (OS). Although radium-223 has a positive effect on OS in men with mCRPC, there has been a paucity of reports from community practitioners, especially with regard to concurrent abiraterone and enzalutamide therapy. Significant differences in patient characteristics encountered may exist.

Patients And Methods: We conducted a retrospective study of men with mCRPC who received at least 1 cycle of radium-223 (n = 35). Baseline pain and ECOG PS as well as concurrent usage of abiraterone or enzalutamide were recorded. Side effect profiles for each patient throughout treatment were noted.

Results: Baseline cohort characteristics include a median age of 75 years. 37% had an ECOG PS ≥ 2 and 23% reported severe pain at baseline. 31% received concomitant enzalutamide 31% concomitant abiraterone. Patients treated concurrently with either abiraterone or enzalutamide did not display additional toxicity. Median cohort OS was 10 months. Patients with no or mild pain had longer median OS than those with moderate or severe pain, 14 versus 7 months (P = 0.028). Patients with ECOG PS < 2 had longer median OS than those with ECOG PS ≥ 2, 13 versus 10 months (P = 0.0233).

Conclusion: This study highlights key differences in patient characteristics encountered by community practitioners. In this population, which presented with clinically advanced disease, there was an improved survival benefit for those treated earlier in their disease. Radium-223 was well tolerated and concurrent treatment with abiraterone or enzalutamide did not add additional toxicity. These 2 points seem to advocate for aggressive and early treatment of patients with radium-223 in the community.