ORLANDO, FL, USA (UroToday.com) - In this retrospective study, the authors looked at practice patterns of the use of radium-223 in patients with metastatic castration-resistant prostate cancer (mCRPC) who had not previously received chemotherapy, paying particular attention to its use in conjunction with abiraterone acetate and enzalutamide.
The authors looked at the outcomes of 51 mCRPC patients with symptomatic bone metastases who received radium-223 between February 2012 and August 2014. In total, 67% and 16% had undergone previous abiraterone and enzalutamide therapy, respectively. Interestingly 47% of patients had visceral metastases. Patients received a median of 5 cycles with only 39% of patients completing all 6 cycles. Reasons for treatment discontinuation included progressive disease (35%), toxicity (8%), and patient decision (4%). Seven patients (14%) remained on study at the time of the study. All patients but one experienced a decline in alkaline phosphatase after radium-223 treatment, however only 40% experienced declines in PSA. In total, grade 3 or 4 adverse events were seen in only 4 patients: 3 with significant anemia and one with thrombocytopenia. A higher proportion of patients on concurrent abiraterone or enzalutamide experienced grade 3 or 4 hematologic complications when compared to those not concurrently on abiraterone or enzalutamide (16% vs 4%), however this was not statistically significant, likely due to the small sample size (p=0.3).
The authors concluded that treatment with radium-223 in conjunction with abiraterone or enzalutamide is safe and feasible. Limitations of this study include the small sample size, as well as the low rate of completion of radium-223 treatment. The addition of patients with visceral metastatic disease, who were not included in the ALSYMPCA trial, also limits any conclusions regarding therapeutic efficacy.
Presented by Hamid Emamekhoo, Rajasree Pia Chowdry, Paul Elson, Elisa M. Ledet, Allison Martin, Patrick Cotogno, Jennifer Beach, Allie E. Steinberger, Kimberly D. Allman, Michael Stolten, Jorge A. Garcia, and Oliver Sartor at the 2015 Genitourinary Cancers Symposium - "Integrating Biology Into Patient-Centric Care" - February 26 - 28, 2015 - Rosen Shingle Creek - Orlando, Florida USA
Reported by Timothy Ito, MD, medical writer for UroToday.com