Dyax calls early halt to Kalbitor clinical trial

BURLINGTON, Mass. -- Dyax Corp. said Thursday it is stopping a clinical trial of its angioedema drug Kalbitor because the drug was not working better than a placebo.

Kalbitor is approved as a treatment for acute attacks of hereditary angioedema, a rare genetic disorder that can cause dangerous swelling of the throat or larynx. Dyax is also studying the drug as a treatment for angioedema attacks caused by a group of drugs called ACE inhibitors. The drugs are used to treat high blood pressure and other conditions and angioedema is a known side effect.

The company said it is assessing its options in developing treatments for angioedema that is caused by ACE inhibitors.

Dyax said initial data from the mid-stage trial showed that Kalbitor was not significantly more effective than a placebo. In part that was because patients who were given the placebo did better than expected. The trial was designed to show that patients who took Kalbitor would be more likely to meet criteria that would allow them to be discharged from emergency rooms six hours after being treated.

Dyax said safety concerns did not play any part in its decision to end the study.

Shares of Dyax rose 7 cents, or 3.4 percent, to close Thursday at $2.14. The stock sank 24 cents, or 11.2 percent, to $1.90 after hours following the announcement.