Zytiga Approved by the FDA for Metastatic Prostate Cancer

The Food and Drug Administration approved Zytiga (abiraterone) to treat metastatic hormone-resistant prostate cancer on April 28, 2011. The approval is for patients who have received prior Taxotere (docetaxel) treatment.

Zytiga marks the third prostate cancer drug approval in the past 12 months. Provenge (sipuleucel-T), a vaccine that stimulates a patient's own immune system to fight cancer was approved on April 29, 2010, and Jevtana (cabazitaxel) was approved shortly after that in June.

Zytiga is a hormone therapy that inhibits a protein called CYP17A1, which helps in producing testosterone. Results of a phase 3 study were presented this past October at the annual meeting of the European Society of Medical Oncology in Milan. The international trial randomly assigned 1,195 men to receive either Zytiga and prednisone or prednisone alone.

The addition of Zytiga improved median survival from 10.9 months to 14.8 months, a 36 percent increase. The drug also slowed time to disease progression from 6.6 months to 10.2 months. About 38 percent of patients experienced a drop in prostate-specific antigen (PSA) of at least 50 percent from baseline compared with 10 percent on prednisone alone. Side effects included fluid retention, low potassium levels, liver function abnormalities and cardiac disorders.

Zytiga had been granted priority review back in late December, which means the FDA would review within six months. The FDA approved Zytiga well before the June 20 deadline.

You can read more about the latest prostate cancer treatments in "Promise for Prostate" from Winter 2010.