FDA panel backs orphan drug for clenched fingers
A Food and Drug Administration advisory panel voted unanimously today to recommend approval of an experimental drug to treat Dupuytren's contracture, a disabling disorder in which the fingers curl, making it difficult to use the hands for everyday activities. The drug, called Xiaflex, is manufactured by Auxilium Pharmaceuticals Inc. of Malvern, Penn. If it is approved, it would be the only drug targeted at the condition.
Depuytren's is a disorder of the tendons that lie beneath the skin of the palm. Collagen forms painful deposits in the palm of the hand that eventually grow into cords stretching from the palm to a joint of the finger. As the cords contract, they force the finger to curl. Currently, the only treatment for the condition is to surgically cut the cords, allowing the fingers to flex. An estimated 3% to 6% of Caucasians, particularly those of Northern European descent, develop the problem, typically after the age of 50.
Xiaflex is a combination of collagen-destroying enzymes isolated from Clostridium histolyticathat are more effective than human collagenase at destroying the cords. It must be carefully injected into the affected joints. A study published two weeks ago in the New England Journal of Medicine on 308 patients showed that 64% of those receiving as many as three injections of the drug in each joint regained a nearly normal range of finger motion, compared with only 6.8% of those who received placebo injections. The primary side effects were swelling and redness at the injection site. About 4% of the patients had contractures recur at an average of 7.4 months--about the same percentage who suffered a recurrence after surgery.
The panel's primary concern was that physicians who will administer the drug be properly trained in the technique. The FDA is not required to follow the recommendations of its advisory panels, but it generally does. Xiaflex has been classified as an orphan drug because of the limited market, providing the company tax incentives for research and a seven-year monopoly on drugs for treating the condition.
Auxilium is also conducting clinical trials of the drug to treat Peyronie's disease, a curving of the penis with a similar mechanism. Analysts predict that the eventual market for the drug to treat both conditions could be about $650 million per year.
-- Thomas H. Maugh II