A Study on the Clinical Outcome of Abiraterone Acetate in Castration Resistant Prostate Cancer Patients

Background: Abiraterone acetate was approved by FDA and EMA in April and September 2011, respectively for treatment of patients with casteration resistant prostate cancer and those previously treated with docetaxel. It is a selective inhibitor of androgen biosynthesis which potentially and irreversibly blocks CYP17, a crucial enzyme in oestrogen and testosterone synthesis. Materials and Methods: This retrospective study was conducted to evaluate the safety and efficacy of abiraterone acetate in the treatment of castration resistant prostate cancer patients. Twenty-two male patients diagnosed with CRPC and experienced treatment failure with one or more lines of treatment (hormonal manipulation or chemotherapy) were selected and administered abiraterone acetate (1,000 mg daily) along with prednisone (5 mg twice daily). Results: Out of 22 patients, 32% had a good response in reduction of PSA values, while 22% had progression in disease and 45% had a stable disease. Potassium, Haemoglobin, and serum sreatinine levels were not affected by the drug. Due to severe GI intolerance, the drug had to be stopped for one patient. The results of this study showed that abiraterone acetate significantly lowered the PSA values and prolonged progression- free survival in metastatic castration resistant prostate cancer patients who had progressed after first-line or second-line treatment. The overall average median survival and the median duration of drug exposure for CRPC who received AA was found to be 11.1 months [range 3-18]. Since AA plus prednisolone are available as oral dosage forms, they can be given in outpatient setting. Conclusion: Abiraterone acetate is a drug of choice for CRPC and also for those who had previously received one or two chemotherapy regimens. Since it is a new therapeutic regimen, this study included small sample size, but there are a few studies indicating the therapeutic efficacy of AA among patients with castration-resistant prostate cancer.