Expedited through the FDA’s priority review program, abiraterone acetate (Zytiga; Centocor Ortho Biotech) in combination with prednisone received approval for the treatment of metastatic castration-resistant prostate cancer in patients who have previously undergone chemotherapy with docetaxel. Abiraterone targets the production of cytochrome P450 17A1 (CYP17A1), a hormone that stimulates cancer-cell growth.
The FDA accelerated abiraterone’s approval ahead of it’s scheduled June 20, 2011, regulatory date.
The recommended dosage for abiraterone is 1000 mg orally once daily in combination with prednisone 5 mg orally twice daily.
In a phase 3 clinical study, 1195 patients with late-stage castrationresistant prostate cancer who had previously received docetaxel chemotherapy were randomized to abiraterone 1000 mg/day with prednisone 5 mg twice daily or a placebo twice daily with prednisone. Among patients who received abiraterone, median OS, the primary end point, was 14.8 months compared with 10.9 months in patients given placebo.
The most common adverse effects with abiraterone were joint swelling or discomfort, hypokalemia, muscle discomfort, diarrhea, urinary tract infection, cough, hypertension, arrhythmia, urinary frequency, nocturia, dyspepsia, and upper respiratory tract infection. (April 28, 2011)
