Abiraterone. After prostate cancer treatment failure: 4-month survival advantage

There is no standard treatment for metastatic prostate cancer that progresses despite castration and cytotoxic chemotherapy. Abiraterone inhibits both testicular and extratesticular androgen synthesis. It has been approved in the European Union for use in this situation, in which treatment options are extremely limited. Clinical evaluation is based on a double-blind comparative trial of good methodological quality that included 1195 patients. The median overall survival time was 4 months longer in the group treated with abiraterone + prednisone (or prednisolone) than in the group treated with placebo + prednisone (or prednisolone): 15.8 versus 11.2 months. The addition of prednisone (or prednisolone) reduced but did not eliminate the effects of hyperaldosteronism induced by abiraterone; oedema occurred in 26.7% of patients, arterial hypertension in 8.5%, and hypokalaemia in 17.1%. Moderate hepatotoxicity was reported with abiraterone and needs to be better assessed. Abiraterone was also associated with cardiac arrhythmias (7.2% versus 4.6% with placebo) and heart failure (1% versus 0.3%). Abiraterone is metabolised by cytochrome P450 isoenzyme CYP3A4 and inhibits isoenzyme CYP2D6, resulting in a high potential for drug interactions. Treatment is somewhat inconvenient. Abiraterone must be taken between meals, serum potassium levels must be monitored, and care must be taken to avoid interactions. Overall, the known risks of abiraterone appear to be acceptable in view of its efficacy, but patients must be carefully monitored. Abiraterone is one option to discuss with patients with metastatic prostate cancer after other treatments fail.