Abiraterone for Prostate Cancer Now Approved in Europe

Zosia Chustecka

September 08, 2011

September 8, 2011 — The novel oral therapy for prostate cancer, abiraterone (Zytiga), has been approved by the European Commission, after an accelerated review by the European Medicines Agency.

Abiraterone was approved in the United States in April, also under an accelerated review process. At that time, Richard Pazdur, MD, an official at the US Food and Drug Administration, noted that the drug "prolonged the lives of men with late-stage prostate cancer who had received prior treatments and had few available therapeutic options."

Data to support the approval come from a pivotal phase 3 trial (COU-AA-301), which have been already been published (N Engl J Med. 2011;364:1995-2005).

At a follow-up of 12.8 months, there was a significant improvement in overall survival among men treated with abiraterone and prednisone, compared with those treated with prednisone alone (14.8 vs 10.9 months; hazard ratio [HR], 0.65; < .001). An updated analysis, at a follow-up of 20.2 months, found similar results, with overall survival improved to 15.8 months, compared with 11.2 months (HR, 0.74).

All 1195 patients in this pivotal trial had metastatic castration-resistant prostate cancer that had progressed despite treatment with docetaxel-based chemotherapy.

This is the indication for which the drug has been approved — in combination with prednisone or prednisolone.

Abiraterone "gives new hope to men who are suffering from this late stage of prostate cancer with very few options left," said one of the investigators on that pivotal study, Karim Fizazi, MD, from the Institut Gustave Roussy in Villejuif, France. Its efficacy, safety, and "ease of use" (it is taken orally) "will address an unmet medical need for many patients," he said in a statement.

Another coinvestigator, Johann de Bono, MD, FRCP, MSc, PhD, from the Institute of Cancer Research at The Royal Marsden Hospital NHS Foundation Trust, in London, United Kingdom, described the new drug as being "well tolerated." The adverse effects were easily manageable and reversible, despite the advanced age and frailty of the study population, the researchers report in the published paper. The most common adverse reactions, as listed on the product labeling, are peripheral edema, hypokalemia, hypertension, and urinary tract infection.

Abiraterone should be taken once a day on an empty stomach, at least 2 hours after eating, and no food should be eaten for at least 1 hour after taking the tablets, the label states.

Novel Mode of Action

Abiraterone is the first oral drug that inhibits androgen production at 3 different sources of the hormones — the testes, adrenal glands, and the tumor tissue itself. It works by inhibiting the CYP17 enzyme complex, which is involved in the production of androgens.