By blocking CYP17, abiraterone acetate (AA) inhibits the production of testosterone and other androgens which are necessary for proliferation and survival of prostate cancer cells.
In September 2011, the European Medicines Agency licensed AA in combination with prednisone or prednisolone for the treatment of metastatic castration resistant prostate cancer (mCRPC) in adult men whose disease has progressed on or after a docetaxel-based chemotherapy regimen.
For this indication, no therapy with demonstrated benefit in overall survival (OS) existed until recently. This has lately changed, because AA is now, besides cabazitaxel, the second regimen for which such improvements have been found. An increase in OS by 3.9 months in patients treated with AA in combination with prednisone in comparison to placebo in combination with prednisone was shown in a phase III study. The observed side-effects were mostly comparable to the placebo group, with the exception of side-effects due to elevated mineralocorticoid levels.
The gains in OS, which can be regarded as a relevant improvement, in addition to an acceptable safety profile indicate that AA + prednisone is currently the most beneficial therapy for mCRPC after docetaxel-based chemotherapy.