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ESMO 2017

ESMO 2017: First Interim Results of the Radium-223 REASSURE Observational Study: Analysis of Patient Characteristics and Safety by Use of Abiraterone and/or Enzalutamide

Madrid, Spain (UroToday.com) Radium-223 prolongs survival with a favorable safety profile among men with metastatic castration-resistant prostate cancer (mCRPC). The pivotal phase III ALSYMPCA trial [1] had a relatively short 3-year follow-up and was conducted before availability of 2nd generation hormonal agents. At this afternoon’s poster session, Dr. Harshman and colleagues presented results of an observational study assessing outcomes of radium-223 by use of abiraterone and/or enzalutamide. The REASSURE study was designed to assess long-term safety (7 years follow-up) and conducted in an era when patients had access to other effective 1st line agents such as abiraterone or enzalutamide.

REASSURE is a global, prospective, single-arm, observational study that enrolled patients with mCRPC with bone metastases planned to start on radium-223. Treatment decision was made independently before enrollment. For the purposes of this study, the authors undertook a planned interim descriptive analysis of safety and drug completion based on prior or concomitant abiraterone or enzalutamide use. This study enrolled 1,106 patients in North America and Europe from September 2014 to September 2016. The interim analysis included 583 pts who received ≥1 dose of radium-223 (median 7 months observation): prior abiraterone or enzalutamide (n=168), or no prior abiraterone or enzalutamide (n=415). Most patients had 6-20 metastasis and more than half completed 5 or 6 radium-223 doses. Prior abiraterone or enzalutamide use was reported in 168 (29%) patients and concomitant in 153 (26%) patients. Treatment-related adverse events occurred in 37% of patients: prior abiraterone or enzalutamide 45%, no prior abiraterone or enzalutamide 34%; concomitant abiraterone or enzalutamide 29%, no concomitant abiraterone or enzalutamide 40%. These were most often gastrointestinal or hematological, with permanent discontinuation of radium-223 in 6% of patients.

In conclusion, radium-223 has a good short-term safety profile when used in the routine clinical practice setting. Prior or concomitant abiraterone or enzalutamide does not appear to increase treatment related adverse event incidence. However, patients who had prior abiraterone or enzalutamide had a lower rate of completing full radium-223 dosing, perhaps reflecting poorer prognosis or more advanced disease as suggested by higher median PSA and LDH levels.

Speaker: Lauren C. Harshman, Dana-Farber Cancer Institute, Boston, United States of America

Co-Authors: J. Logue (Manchester, United Kingdom) C. N. Sternberg (Roma, Italy) S. Sundar (Nottingham, United Kingdom) D. Schrijvers (Antwerp, Belgium) M. Schostak (Magdeburg, Germany) J. Sylvester (Lakewood Ranch, United States of America) S. George (Buffalo, United States of America) M. Tucci (Orbassano, Italy) C. Mantz (Fort Myers, United States of America) P. Borrega (Cáceres, Spain) P. Ziem (Neubrandenburg, Germany) R. Concepcion (Nashville, United States of America) K. Miller (Berlin, Germany) O. Sartor (New Orleans, United States of America) J. Kalinovsky (Bratislava, Slovak Republic) Y. De Sanctis (Whippany, United States of America) B. Tombal (Brussels, Belgium)

Written By: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre, Twitter: @zklaassen_md at the European Society for Medical Oncology Annual Congress - September 8 - 12, 2017 - Madrid, Spain

References:

1. Parker C, Nilsson S, Heinrich D, et al. Alpha emitter radium-223 and survival in metastatic prostate cancer. N Engl J Med 2013;369(3):213-223.