CUA 2017: Analysis of Real-World use of Radium-223 in Ontario

Toronto, Ontario ( Dr. Urban Emmenegger and colleagues presented their study assessing real-world utilization of the alpha emitter Radium-223 at the prostate cancer poster session at the 2017 CUA annual meeting. Based on the ALSYMPCA trial, we know that Radium-223 improves survival and delays skeletal related events (SREs) among patients with metastatic castration-resistant prostate cancer (mCRPC) to the bone.1

However, even in the ALSYMPCA trial, only 63% of patients received the maximum six cycles of Radium-223, whereas in the real-world setting patients are typically older with more comorbidities than those participating in clinical trials. As such, the objective of this study was to assess the real-world use of Radium-223 in four Ontario cancer centers.

This retrospective study included 199 men with mCRPC patients receiving ≥1 dose of Radium-223 from January 2015 to April 2016. The co-primary outcomes were number of patients receiving all six Radium-223 cycles and reasons for treatment discontinuations for men receiving <6 cycles. Secondary outcomes included baseline disease characteristics, proportion of patients achieving a >30% PSA response, >50% PSA response and alkaline phosphatase (ALP) normalization, as well as adverse events. Among included patients, the median age was 75 years (range 52-93), median PSA was 76.4 ng/mL (range 0.8-6500), 21% of patients had ALP ≥220 U/L (median 113 U/L), and median hemoglobin was 12 g/dL (range 1.2-16.1). The most common prior treatment was docetaxel (50% of patients). Ninety-one patients (46%) received the maximum six cycles. The main reasons for early treatment discontinuation included symptomatic disease progression (38%), symptom concern (11%), and neutropenia (11%). In patients receiving ≥3 cycles of Radium-223, 13% of patients had >30% PSA decline, 6% had >50% PSA decline, and ALP normalization was observed in 25% of patients with baseline ALP elevation. There were no unexpected adverse events.

In conclusion, in an older, real world population with comparable disease characteristics to those enrolled in ALSYMPCA, Radium-223 was safely administered but the proportion of patients receiving all six cycles of treatment was low (and lower compared to patients in ALSYMPCA). Future pooled analyses on a larger scale would increase the sample size to allow for analysis of factors predicting early Radium-223 termination.

Presented By: Urban Emmenegger, MD, Sunnybrook Odette Cancer Centre, Toronto, ON, Canada

Co-Authors: Sierra Cheng, Leigha Rowbottom, Rachel McDonald, Ronald Chow, Neil E. Fleshner, Pawel Zalewski, Anil Kapoor, Edward Chow

Written By: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre  Twitter: @zklaassen_md at the  72nd Canadian Urological Association Annual Meeting - June 24 - 27, 2017 - Toronto, Ontario, Canada

1. Parker C, Nilsson S, Heinrich D, et al. Alpha emitter radium-223 and survival in metastatic prostate cancer. N Engl J Med 2013 Jul 18;369(3):213-223.