EAU 2017: Radium-223 (Ra-223) in sequence or in concurrent use with abiraterone acetate (AA) or enzalutamide (E) in metastatic castration resistant prostate cancer (mCRPC) patients treated in an international early access program (iEAP)

London, England (UroToday.com) This morning’s advanced prostate cancer poster session was highlighted by Dr. Fred Saad’s presentation assessing the efficacy and safety of sequential vs concurrent use of Radium-223 (Ra-223) and abiraterone acetate (AA). This is a timely discussion with the emergence of new treatment options over the past few years for patients with metastatic castration-resistant prostate cancer (mCRPC).

The authors performed a post hoc analysis of patients enrolled in the international early access program (iEAP) single-arm, phase 3b study of mCRPC patients (n=708) receiving up to 6 cycles of Ra-223. The primary endpoints for the study were overall survival (OS) and safety outcomes. Among the cohort, 32 % (n=228) received Ra-223 after AA and 17% (n=119) received Ra-223 concurrently with AA. Patients receiving concurrent therapy had more favorable baseline characteristics (lower ALP, lower PSA and less exposure to docetaxel) compared to patients receiving Ra-223 after AA. These clinical parameters also translated into improved performance status (ECOG 0: 42% vs 36%; ECOG 1: 47% vs 52%) for patients receiving concurrent therapy. Importantly, 26% of patients receiving concurrent therapy died during follow-up compared to 40% receiving sequential therapy, with improvement in median OS (Ra-223 after AA: 12 months; 95%CI 9.7-14.3 vs Ra223 + AA: 18.1; 95%CI 11.7 months – NR) (HR 0.56; 95%CI 0.39-0.82). Patients receiving concurrent Ra-223 + AA had fewer any grade, or serious adverse events.

In summary, healthier patients at baseline may be able to tolerate concurrent Ra-223 and AA, and may have improvement in OS compared to patients receiving Ra-223 after AA. As the authors conclude, we eagerly await the results of the ongoing ERA-223 and PEACE-3 phase 3 randomized clinically trials to further evaluate potential advantages of Ra-223 administered with AA or enzalutamide. These trials will represent patients in the chemo-naïve setting, whereas nearly ¾ of patients in the iEAP previously received docetaxel.

Presented by: Fred Saad, Department of GU Oncology, University of Montreal Hospital Center, Montreal, Canada

Written by: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto
Twitter: @zklaassen_md

at the #EAU17 -March 24-28, 2017- London, England