AUA 2017: Efficacy And Safety of Radium-223 By Radical Local Therapy at Initial Diagnosis: A Retrospective Subgroup Analysis of Alsympca Trial

Boston, MA ( Radium-223 (Ra-223), a targeted alpha therapy, significantly improved overall survival (OS) compared to placebo in patients with metastatic castration resistant prostate cancer (mCRPC) in the ALSYMPCA trial (HR = 0.70; 95% CI, 0.58-0.83; P < 0.001). Dr. Klotz and the coauthors hypothesized that outcome with Ra-223 in ALSYMPCA would be similar whether or not patients underwent radical local therapy for prostate cancer (PC) at initial diagnosis.

ALSYMPCA eligible patients had progressive mCRPC with ≥2 bone lesions and no known visceral metastases. Patients were randomized 2:1 to either 6 injections of Ra-223 (55 kBq/kg IV; q4 wk) plus best standard of care. Exploratory subgroup analyses were performed to evaluate outcome of Ra-223 vs placebo by radical local therapy (defined as radical prostatectomy or radiation to the prostate) and according to metastatic status at initial diagnosis.

921 pts were treated (Ra-223, n = 614; placebo, n = 307). 392 (43%) received radical local therapy at initial diagnosis and 529 (57%) did not. Median OS was longer with Ra-223 vs placebo regardless of whether patients received radical local therapy or not [(with RLT: 15.3 vs 11.8 mo, HR: 0.704 (0.523-0.948); without radical local therapy: 14.7 vs 10.8 mo; HR: 0.684 (0.543-0.862)]. Metastatic status at diagnosis was documented for 576 pts (63%); 306 were documented as non-metastatic (M0) and 270 as metastatic (M1). Median OS was longer with Ra-223 vs placebo, regardless of metastatic status at diagnosis [M0: 14.1 vs 9.6 mo, HR: 0.674 (0.491-0.925); M1: 15.6 vs 11.5 mo, HR: 0.638 (0.454-0.895)]. Therapies received prior to ALSYMPCA trial initiation were mainly radical local therapy (mostly M0), bilateral orchiectomy, LHRH agonist, anti-androgens, chemotherapy and external radiotherapy to bone. These prior therapies were generally balanced between Ra-223 and placebo groups.

Dr. Klotz concluded and said that compared with placebo, Ra-223 improved OS in mCRPC patients. A subgroup analysis indicated that OS is consistent regardless of whether patients had received radical local therapy or not at initial diagnosis. Similarly, OS is consistent regardless of metastatic status at initial diagnosis.

Presented by: Laurence Klotz, Toronto, Canada

Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre

Twitter: @Goldberghanan

at the 2017 AUA Annual Meeting - May 12 - 16, 2017 – Boston, Massachusetts, USA