Dyax, Genzyme end deal

Cambridge biotech company Dyax Corp. has agreed to end its deal with Genzyme Corp. to co-develop a drug for a rare swelling disorder called hereditary angioedema. The firms were jointly testing DX-88, a small protein considered Dyax's most important potential drug.

Dyax said in a press release that it will receive all the assets of the joint development deal along with a $17 million cash payment. Genzyme will receive 4.4 million shares of Dyax stock. The news, released after the close of market, sent Dyax stock tumbling more than 15 percent in after-hours trading.

The companies first signed the DX-88 deal in 1998, but in a sense their relationship extends much farther back: Dyax chairman and chief executive Henry Blair was a founder of Genzyme and remains on Genzyme's board of directors.

Dyax and Genzyme recently completed a Phase III clinical trial for DX-88, with results expected in the second quarter of htis year. The company plans to disclose more information on a conference call tomorrow morning, when it discusses fourth-quarter financial results with investors. By Stephen Heuser, Globe staff