Abstract: PD24-05
Sources of Funding: Prostate Cancer Canada Discovery Grant 2013_x000D_ Cote-Sharp Family Foundation

Introduction

Abiraterone was introduced in Quebec in 2012 for metastatic castration-resistant prostate cancer (mCRPC) in the post-docetaxel setting. This study described abiraterone utilization in the early post-approval period and its clinical effectiveness in Quebec, for both post-chemotherapy patients and patients unfit for chemotherapy.

Methods

A retrospective cohort study was conducted using Quebec public healthcare administrative databases. The study population consisted of men 40 years and older with a diagnosis of prostate cancer (PCa), and who received androgen-deprivation therapy (ADT) (orchiectomy or luteinizing hormone-releasing hormone analogs or antagonists (LHRHa)) between January 2001 and July 2013. In addition, patients should have received a first treatment of abiraterone between 2012 and 2013. Treatment groups were defined as: 1) Abiraterone post chemotherapy and 2) Abiraterone “exception patient”, for chemotherapy-ineligible patients treated with abiraterone authorized by the “exception patient” measure category. Study outcomes included overall survival since abiraterone initiation, abiraterone duration, and hospitalization days. Cox proportional hazard regression was used to estimate the effectiveness of abiraterone in the post-docetaxel setting adjusted for several covariates.

Results

Our cohort consisted of 303 mCRPC patients treated with abiraterone (abiraterone post-chemotherapy: 99 and abiraterone “exception patient”: 204). The median age was 75.0 for the abiraterone post-chemotherapy group and 80.0 for the abiraterone “exception patient” group. The corresponding median survivals were 12 and 14 months, respectively (log-rank test p-value=0.815). Risk of death was similar in the abiraterone post-chemotherapy and abiraterone “exception patient” groups (hazard ratio (HR): 0.89; 95%CI 0.57-1.38).

Conclusions

Effectiveness of abiraterone in older patients who were chemotherapy ineligible was similar to that of patients with prior docetaxel exposure. Overall, real-world survival benefits of abiraterone were similar to the results of the COU-AA-301 trial.

Funding

Prostate Cancer Canada Discovery Grant 2013_x000D_ Cote-Sharp Family Foundation