Healthy results for ZymoGenetics compound

The primary aim of the trial was to assess efficacy by comparing the effectiveness of rhThrombin as a surgical hemostat to the currently approved bovine-derived thrombin, as measured by the incidence of hemostasis.

Four types of surgery were examined in the trial: spinal surgery, liver resection, peripheral artery bypass and arteriovenous graft construction. The study was designed to support broad product labeling for the use of rhThrombin as an aid to controlling bleeding during surgery.

Treatment with rhThrombin and bovine thrombin showed increases in the number of antibodies in patients after the therapy was administered and was also effective in treating severe surgical bleeding.

The rate of antibody formation was 1.5% in response to treatment with rhThrombin, versus 22% for those treated with the bovine thrombin product. Of patients in the bovine thrombin group who had pre-existing antibodies to the bovine thrombin product, eight of ten showed a ten-fold or greater increase in antibody levels over baseline measurements. The overall antibody generation rate for the bovine thrombin product was within the range that has been reported in recent scientific literature.

“In this study, recombinant human thrombin showed a superior immunogenicity profile to bovine thrombin,” said Bruce Carter, President and CEO of ZymoGenetics. “We remain on schedule for the filing of a Biologics License Application with the FDA before the end of this year.”

The trial results will be presented at the Society for the Advancement of Blood Management (SABM) annual meeting. ZymoGenetics will also review detailed results from the rhThrombin phase III clinical trial at an analyst and investor briefing to be held on September 18, 2006.