Impact of Abiraterone Acetate and Enzalutamide on Symptom Burden of Patients with Chemotherapy-naive Metastatic Castration-resistant Prostate Cancer.

Aims: Treatments and disease burden of metastatic castration-resistant prostate cancer (mCRPC) considerably affect a patient's quality of life. However, patient-reported symptom burden data are still largely insufficient. This study sought to compare the self-reported symptom burden of men with chemotherapy-naive (CN) mCRPC treated with abiraterone acetate (AA) or enzalutamide (EZ) in routine clinical practice.

Materials And Methods: Between 2011 and 2015, 189 CN-mCRPC patients who had received AA (n = 76) or EZ (n = 113) at the Princess Margaret Cancer Centre were included. The Edmonton Symptom Assessment System (ESAS) score, baseline demographic information, comorbidities, Eastern Cooperative Oncology Group performance status, laboratory data and narcotic analgesic use were recorded for each patient. The minimal clinically important difference was assessed using ±1 point change from baseline for each ESAS symptom. Mixed model for repeated measures (MMRM) was used to estimate and compare the longitudinal ESAS score changes from baseline in AA and EZ groups adjusted for age, baseline ESAS scores, treatment group, treatment duration and time.

Results: The median (interquartile range) treatment duration with AA and EZ was 10 (6-16) and 12 (7-18) months, respectively (P = 0.19). Fatigue was rated the most distressing symptom at baseline and following treatment in both groups. There were no statistically significant differences in the proportion of patients with clinically meaningful symptom improvement or worsening after AA or EZ administration in any of the ESAS-based physical and psychological symptoms over time. In MMRM analyses, there were no significant differences in adjusted mean scores from baseline to 3, 6, 9 and 12 months for any of the ESAS items between AA and EZ groups.

Conclusion: Physical and psychological symptoms assessed by ESAS were comparable in CN-mCRPC men treated with AA or EZ in the real-world clinical setting. Further studies are warranted to confirm these findings.