rhThrombin Safe in Stopping Bleeding in Vascular Surgery
Jun 20, 2005, 19:06, Reviewed by: Dr.
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"I'm encouraged to see that recombinant human thrombin may be a safe and effective tool to stop bleeding in vascular surgery."
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By ZymoGenetics, Inc.,
ZymoGenetics, Inc. (Nasdaq:ZGEN) today announced highlights from a presentation given by clinical investigator Jeffrey H. Lawson, M.D. of Duke University Medical Center at the spring meeting of the Peripheral Vascular Surgery Society in Chicago, Illinois.
The presentation, titled "Phase 2 Evaluation of Topical Recombinant Human Thrombin for Hemostasis in Subjects Undergoing Vascular Surgery," discussed findings of two clinical trials conducted with patients undergoing either arteriovenous grafting surgery for hemodialysis access or peripheral artery bypass surgery.
The primary objective of these randomized, double-blinded clinical trials was to assess the safety of rhThrombin as a surgical hemostat. Secondary objectives included determinations of immunogenicity and point estimates of time to hemostasis.
A total of sixty patients had gelatin sponges saturated with either rhThrombin or placebo applied to sites of bleeding during surgery. Assessments were made thereafter to determine the time at which bleeding was stopped by either treatment. Patients with continued bleeding at the selected sites after ten minutes were given further treatment with open-label rhThrombin or other hemostatic measures at the discretion of the surgeon. Twenty-eight days after surgery, patients completing the study had blood drawn to determine whether antibodies had formed against rhThrombin.
Conclusions from the studies included the following:
-- rhThrombin appeared to be safe and well-tolerated.
-- Only one of thirty-seven exposed patients (2.7 percent) produced detectable antibodies to rhThrombin. This compares favorably to published results of studies involving bovine thrombin, in which over forty percent of treated patients generated antibodies to the bovine product (Ortel, 2001).
-- Ninety percent of rhThrombin-treated bleeding sites achieved hemostasis by ten minutes, compared to only seventy-four percent of those treated with placebo. The average time to hemostasis in rhThrombin-treated patients was twenty-seven percent lower than in patients treated with placebo.
-- Rescue hemostasis with rhThrombin at sites with continued bleeding at ten minutes was effective in over ninety percent (twelve of thirteen) cases in which it was used.
"I'm encouraged to see that recombinant human thrombin may be a safe and effective tool to stop bleeding in vascular surgery," stated Dr. Lawson. "While more studies will be needed to demonstrate the safety and effectiveness of rhThrombin, the surgical community needs to become more aware of the potential risks to patients of using the currently marketed bovine product," added Dr. Lawson.
The two vascular trials were part of a four-part Phase 2 clinical study program for rhThrombin, which also included spinal and liver resection surgeries. All studies in the program met their primary endpoint of safety as well as their secondary endpoints of evaluating immunogenicity and obtaining point estimates of time to hemostasis. Results from these Phase 2 studies are being used to guide ZymoGenetics in establishing parameters for a pivotal trial program, which is expected to start in the second half of 2005.
Presentation
Dr. Lawson's presentation about rhThrombin at the Peripheral Vascular Surgery Society Spring Meeting was given on the afternoon of Friday, June 17, 2005. The presentation slides will be available at www.zymogenetics.com in the "What's New" section of the home page.
About rhThrombin
ZymoGenetics is developing rhThrombin for the control of bleeding associated with surgical procedures. Thrombin is used in over 500,000 surgeries per year in the United States. Currently, only thrombin derived from cow blood is available in the U.S. as a stand-alone thrombin product. Bovine-derived thrombin has been associated with the development of antibodies that may cross-react with human blood proteins. In some cases, these antibodies lead to serious bleeding complications. Recombinant proteins, such as rhThrombin, can be manufactured to higher levels of purity and consistency than proteins purified from human or animal blood. Furthermore, the production of recombinant proteins is not dependent on the availability of blood from human or animal donors and can be scaled-up to meet market demands. For these reasons, ZymoGenetics believes that rhThrombin represents a potential preferred alternative to the bovine-derived product. 
- The data was presented at the spring meeting of the Peripheral Vascular Surgery Society in Chicago, Illinois.
www.zymogenetics.com
About ZymoGenetics
ZymoGenetics is a biopharmaceutical company focused on the discovery, development and commercialization of therapeutic proteins for the prevention or treatment of human diseases. The Company is developing a diverse pipeline of potential proprietary product candidates that are moving into and through clinical development. These span a wide array of clinical opportunities that include bleeding, autoimmune diseases and cancer. ZymoGenetics intends to commercialize these product candidates through internal development, collaborations with partners and out-licensing of patents from its extensive patent portfolio. For further information, visit www.zymogenetics.com.
Forward Looking Statements
This press release contains "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are based on the current intent and expectations of the management of ZymoGenetics. These statements are not guarantees of future performance and involve risks and uncertainties that are difficult to predict. ZymoGenetics' actual results and the timing and outcome of events may differ materially from those expressed in or implied by the forward-looking statements because of risks associated with our unproven discovery strategy, preclinical and clinical development, regulatory oversight, intellectual property claims and litigation and other risks detailed in ZymoGenetics' public filings with the Securities and Exchange Commission, including ZymoGenetics' Annual Report on Form 10-K for the year ended December 31, 2004. Except as required by law, ZymoGenetics undertakes no obligation to update any forward-looking or other statements in this press release, whether as a result of new information, future events or otherwise.
Contacts
ZymoGenetics, Inc.
John Calhoun, MD, MBA, 206-442-6744 (Investor Relations)
or
Susan W. Specht, MBA, 206-442-6592 (Media Relations)
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