San Francisco, CA USA (UroToday.com) Researchers who examined treatment adherence among men with metastatic castration-resistant prostate cancer (mCRPC) who were treated with enzalutamide or abiraterone acetate, found significantly higher rates of refill gaps of 30- or 60- days or longer among enzalutamide-treated patients. This finding, from a retrospective analysis reported at the 2016 ASCO Genitourinary
Cancers Symposium, points to a need for better understanding of factors that may lead to treatment interruptions, such as drug-drug interactions, intolerance, or toxicities that result in patients’ undertaking dose reductions.
For this study, authors Ajay Behl, PhD, MBA, Lorie Ellis, PhD, from Janssen Scientific Affairs in Canada and the United States, along with co-investigators at the Lombardi Comprehensive Cancer Center in Washington D.C., examined data from the large Truven Health MarketScan Research Database of mCRPC patients who were initiated on abiraterone or enzalutamide between October 1, 2012 and December 31, 2014.
Patients with 6 months or more of continuous eligibility were observed by investigators until they were either lost to follow-up or until data became unavailable. Kaplan-Meier (KM) survival curves were used to compare the rates of having a refill gap of 14, 30, or 60 or more days following 6 months of observation. The time to a first refill gap was evaluated in 2,591 patients receiving abiraterone and 807 patients receiving enzalutamide.
Author Ajay Behl, speaking to UroToday about the study’s findings noted that, the efficacy of cancer treatments depends upon patients’ consistency in adhering to recommended dosage regimens. This study provided new information on this issue. “To our knowledge, this is the first study to assess and compare treatment patterns and adherence of abiraterone and enzalutamide in real world settings. The use of different measures for adherence, use of alternative definitions for dose reduction, and assessment of adherence at different time points over follow-up support the robustness of our study results. We are currently working on a couple of manuscripts with significantly more detailed analysis, results and discussions.”
The study’s authors calls for the development of strategies to help patients avoid compromising the survival benefits that accrue from these novel oral therapies taken at their recommended dosages.
Behl A, Ellis L, Pilon D, et al. Gaps in treatment amongst metastatic castration resistant prostate cancer (mCRPC) patients taking abiraterone acetate or enzalutamide. ASCO Genitourinary Cancers Symposium, San Francisco, CA. January 7-9, 2016. Available at: http://meetinglibrary.asco.org/content/158071-172