Gaps in treatment amongst metastatic castration resistant prostate cancer (mCRPC) patients taking abiraterone acetate or enzalutamide.

Abstract

334 Background:Abiraterone acetate (ABI) and enzalutamide (ENZ) are novel oral therapies offering survival benefit to metastatic castration-resistant prostate cancer (mCRPC) patients. The efficacy of cancer treatments rely on patient consistency and adherence to recommended dosage regimens. Factors such as drug-drug interactions and intolerance or toxicities can result in patients or their providers reducing the drug dosage. This study aims to describe treatment discontinuation patterns observed for ABI and ENZ. Methods: The Truven Health MarketScan Research Databases were used to conduct a retrospective analysis of mCRPC patients initiated on ABI or ENZ (index date) between 10/01/2012 to 12/31/2014 with ≥6 months of continuous eligibility prior to index date and a PC diagnosis during the period of continuous eligibility. Patients were observed until loss to follow-up, or end of data availability. Kaplan-Meier (KM) survival curves were used to compare the rates of having a refill gap (i.e., ≥14 days, ≥30 days, or ≥60 days) in patients initiated on ABI or ENZ. Results: The table below summarizes the KM probabilities of having a refill gap among patients initiated on ABI or ENZ. Conclusions: Significantly higher rates of refill gaps ≥30 days and ≥ 60 days were observed for patients initiating ENZ as compared to ABI after 6 months of observation in this initial analysis. Additional research is needed to understand the reasons for gaps in treatment in patients treated with mCRPC therapies. [Table: see text]