Phase II clinical study of radium-223 chloride (BAY 88-8223) in Japanese patients with symptomatic castration-resistant prostate cancer (CRPC) with bone metastases.

Abstract

167 Background: The ALSYMPCA study was conducted to evaluate the alpha-emitting radiopharmaceutical Radium-223 Chloride (BAY 88-8223) in patients with symptomatic bone metastases in Castration resistant prostate cancer (CRPC). This trial met its primary endpoint of overall survival at the time of pre-planned interim analysis. Post hoc analysis showed a reduction from baseline in total ALP at 12 weeks (32% reduction in the BAY 88-8223 arm vs. 37% increase in placebo arm, P < 0.001) (Sartor et al. ASCO 2013). We are reporting here a single-arm, open-label, multicenter, phase II clinical study of BAY 88-8223 in Japanese patients with symptomatic CRPC with bone metastases. Methods: Eligible patients had progressive, symptomatic CRPC with at least 2 bone metastases on bone scintigraphy and no known visceral metastases; were receiving Best Standard of Care; and either had previously received docetaxel, were docetaxel ineligible, or had refused docetaxel. Patients received 6 injections of radium-223 (50 kBq/kg IV) every 4 weeks. The primary endpoint was percentage of change in total ALP from baseline at 12 weeks. Secondary endpoints included overall survival, time to symptomatic skeletal event, percentage of change in bone ALP/PSA/biomarkers, and safety. Results: A total of 67 subjects were enrolled; 18 were screening failures, and 49 were received to the study treatment and received at least one administration from September 2013 to May 2014. The mean percent change in total ALP from baseline at 12 weeks was -19.3% (95%CI: -28.0% to -10.7%). The results of secondary endpoints will be presented. The safety and tolerability profile for BAY 88-8223 were highly favorable and only 1 subject (2.0%) experienced lymphocyte count decreased as a Grade 4 adverse event, and there was no death during the study treatment and within 30 days after the last injection of study treatment. Conclusions: The reduction from baseline in total ALP at 12 weeks seen in this phase II study is consistent with the results shown in ALSYMPCA study. Overall, BAY 88-8223 was well tolerated in Japanese patients with CRPC and bone metastases. Clinical trial information: NCT01929655.