Centocor Ortho Biotech has applied to the European Medicines Agency for authorisation to market abiraterone, which blocks androgen synthesis by inhibiting the enzyme CYP17 (also known as 17α-hydroxylase/17,20 lyase).
The licence application includes data from the COU-AA-301 study, in which patients who received abiraterone survived 35% longer than those who took placebo.
Study investigators randomised 1,195 men with castration-resistant prostate cancer to undergo treatment with abiraterone 1g once daily or placebo, in addition to low-dose prednisolone/prednisone. All participants had been previously treated with docetaxel. Results of the study were presented at the 35th ESMO congress in Milan on 11 October 2010.
Compared with placebo, abiraterone extended median survival from 10.9 months to 14.8 months (p<0.00001). Patients who received abiraterone also showed a prolonged time to PSA progression, extended radiographic progression-free survival and an increased rate of PSA response.
"This should be considered a major step forward in prostate cancer therapeutics," said lead investigator Johann de Bono, from The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London. "These results are likely to be practice-changing for men with advanced prostate cancer that has progressed on docetaxel-based chemotherapy, which has been a critical unmet need."
Mineralocorticoid-related adverse events were more common with abiraterone than placebo, with fluid retention occurring in 30.5% (versus 22.3%) of patients and hypokalaemia in 17.1% (versus 8.4%).
Two other treatments are generating further hope for patients with this hard-to-treat form of prostate cancer. The personalised immunotherapy sipuleucel-T (Provenge) is currently in Phase 3 trials and the microtubule inhibitor cabazitaxel (Jevtana) is awaiting European approval.