Quality-of-Life in CRPC Patients Treated With Enzalutamide Versus Abiraterone: Impact of Standard and Modified Dosing

BACKGROUND: Head-to-head comparisons between enzalutamide (ENZ) and abiraterone plus prednisolone (ABI) have shown comparable survival benefits in patients with castration-resistant prostate cancer (CRPC). However, the quality of life (QoL) associated with these agents has not been directly compared. We conducted a sub-analysis to evaluate longitudinal changes in QoL within each treatment arm. METHODS: The ENABLE study for PCa, an investigator-initiated, multicenter, randomized controlled trial, was performed. Patient-reported QoL was assessed using the Functional Assessment of Cancer Therapy-General (FACT-G) questionnaire, including subscales of physical, social, emotional, and functional well-being, at predefined timepoints. RESULTS: A total of 89 patients were included in each arm, with 76 (ENZ) and 74 (ABI) responding to the questionnaires. There were no significant differences in time to prostate-specific antigen progression or overall survival between arms (P = .1694 and P = .6306). ENZ did not change the total FACT-G score during the treatment course (P = .9585), whereas ABI significantly and gradually deteriorated it (P = .0003). In the ABI arm, the standard dose (1000 mg/d) significantly deteriorated the total FACT-G score (n = 55, P = .0003), while the modified dose (≤ 750 mg/d) did not (n = 15, P = .1816). Subscale analysis showed that ENZ did not deteriorate any domains, whereas ABI significantly worsened social and functional well-being (P = .0128 and P = .0006, respectively). Further analysis revealed that the modified dose of ABI did not deteriorate social or functional well-being (P = .6549 and P = .5837, respectively) while the standard dose significantly worsened both (P = .0010 and P < .0001, respectively). CONCLUSIONS: ABI deteriorated QoL over time, with the standard dose being the main contributor. The modified dose of ABI may represent a better treatment option to preserve QoL.