Safety and Clinical Outcomes of Abiraterone Acetate After Docetaxel in Octogenarians With Metastatic Castration-Resistant Prostate Cancer: Results of the Italian Compassionate Use Named Patient Programme

Abstract

Metastatic castration-resistant prostate cancer mainly affects older men, opening issues about the efficacy and safety of therapies in this population. We have demonstrated that abiraterone, a selective androgen biosynthesis inhibitor, is a safe and active therapeutic option in a subgroup of 47 very elderly adults (aged > 80 years) enrolled in the Italian named patient program, with a tolerability profile and clinical outcomes comparable to those of younger population.

Background: Prostate cancer mainly affects elderly men, who are often frail and whose reduced physiological reserves and multiple comorbidities increase the risk of side effects. The availability of new drugs has improved the overall survival (OS) of patients with castration-resistant prostate cancer (CRPC) but has increased the number of very elderly CRPC patients receiving anticancer drugs, raising questions about their efficacy and safety in this population.

Patients and methods: We assessed the tolerability of abiraterone (AA) in a cohort of very elderly adults with metastatic CRPC (mCRPC) enrolled in the Italian AA named patient program and analyzed their clinical outcomes. We retrospectively reviewed the clinical records of 47 mCRPC patients aged > 80 years who had received AA after docetaxel. The Kaplan-Meier method was used to calculate OS and progression-free survival (PFS). Safety and clinical outcomes were also analyzed by age group (< 80 and > 80 years). Cox regression analysis was used to calculate the differences in PFS and OS between the groups according to the stratification variables.

Results: In very elderly men, the prostate-specific antigen response rate was 48.9%, and the median PFS and OS were 8 and 18 months, respectively. The differences in toxicities between the older and younger age groups were not major. The limitation of the present study was mainly its retrospective nature.

Conclusion: Our data show that AA is active and safe in very elderly patients and leads to outcomes similar to those observed in younger patients, thus confirming that AA is a manageable therapeutic option for this patient population.

Keywords: Abiraterone; Castration-resistant prostate cancer; Elderly; Outcomes; Safety.