Plenaxis (abarelix): Drug for Advanced Prostate Cancer
The FDA has approved a New Drug Application (NDA) that permits marketing of Plenaxis (abarelix), a drug for advanced prostate cancer for patients who have no alternative therapy. The drug is indicated for, and restricted for use in, men with advanced prostate cancer who cannot take other hormone therapies and who have refused surgical castration. It will be marketed under a voluntary risk management program (RMP) that restricts the use of Plenaxis to prostate cancer patients who have no alternative therapy because of an increased risk of serious and potentially life-threatening allergic reactions to the drug. About 5% to 10% of men with prostate cancer have the type of advanced symptomatic disease that would make them candidates for Plenaxis.
Plenaxis, a gonado-tropin-releasing hormone (GnRH) antagonist, lowers testosterone levels, which are a key factor in most prostate cancer growth. The effectiveness of Plenaxis in lowering testosterone production in men with advanced symptomatic prostate cancer was demonstrated in a study of 81 men that showed that such patients could avoid surgical castration by undergoing at least 12 weeks of treatment. Some men also experienced other benefits, including decreased pain and relief from urinary problems. However, three of the 81 patients experienced serious allergic reactions, one of which involved loss of consciousness.
Because of the risk of low blood pressure and fainting as part of the allergic reaction to Plenaxis, the drug will be distributed directly to physicians and hospital pharmacies enrolled in the Plenaxis RMP.