FDA approves abiraterone for metastatic castration-resistant prostate cancer

The FDA announced Thursday that it has approved the oral androgen biosynthesis inhibitor abiraterone acetate for the treatment of metastatic castration-resistant prostate cancer.

Abiraterone (Zytiga, Centocor Ortho Biotech) works by inhibiting the CYP17 enzyme complex. The indication calls for the drug to be used in combination with prednisone for men who have received prior chemotherapy with docetaxel.

FDA approved abiraterone based on the results of a phase-3 randomized, placebo-controlled, multicenter study which showed that the drug was associated with a significant increase in median OS. Patients (n=1,195) were assigned to once daily abiraterone in combination with prednisone or placebo twice daily in combination with prednisone.

At pre-specified interim analysis, OS was 14.8 months in the experimental group vs. 10.9 months for placebo. Risk for death decreased by 35% in the experimental group (HR=0.646; 95% CI; 0.543-0.768). An updated analysis showed a 4.6-month difference in OS favoring abiraterone, 15.8 months vs. 11.2 months (HR=0.74).

The most common adverse events reported included joint swelling or discomfort, hypokalemia, edema, muscle discomfort, hot flush, diarrhea, urinary tract infection, cough, hypertension, arrhythmia, urinary frequency, nocturia, dyspepsia and upper respiratory tract infection.

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