New treatment for advanced prostate cancer

FDA Consumer, March-April, 2004

Men with advanced cases of prostate cancer now have an additional treatment option. In November 2003, the FDA approved Plenaxis (abarelix), a drug given as an injection. Plenaxis lowers the male hormone testosterone, a key factor involved in most prostate cancer growth.

Because of an increased risk of serious and potentially life-threatening allergic reactions, use of Plenaxis is restricted to advanced prostate cancer patients who have no alternative therapy. The drug is distributed directly to physicians and hospital pharmacies enrolled in a risk management program. Plenaxis is not distributed through retail pharmacies.

The effectiveness of Plenaxis in lowering testosterone production was demonstrated in a study of 81 men with advanced prostate cancer. The study showed that the men could avoid surgical castration by undergoing at least 12 weeks of treatment. Some men also experienced other benefits, such as decreased pain. But three of the men experienced serious allergic reactions, one of which included loss of consciousness.

Because of the risk of low blood pressure and fainting as part of the allergic reaction, men being treated with Plenaxis should be monitored for at least 30 minutes after receiving a dose of the drug in their health provider's office. The most common side effects of Plenaxis are hot flashes, sleep disturbances, back pain, breast enlargement or pain, and constipation.

Plenaxis is marketed by Praecis Pharmaceuticals Inc. of Waltham, Mass.