Washington Editor

The FDA Thursday approved ZymoGenetics Inc.'s Recothrom Thrombin, the first and only recombinant, plasma-free thrombin for use as a topical hemostat.

News of the approval sent shares of ZymoGenetics (NASDAQ:ZGEN) up $1.05, or 8.8 percent, to close at $13.05.

The product, formerly known as rThrombin, is indicated for use during surgery to control minor bleeding from capillaries and small venules when standard surgical techniques for stopping blood loss are ineffective or impractical.

Recothrom is made from Chinese hamster ovary cells (CHO) that have been modified genetically to produce human thrombin. Those CHO cells "are free from known infectious agents, and Recothrom undergoes an additional process of viral inactivation," the FDA said in a statement.

The product's U.S. approval triggered a $40 million milestone payment to Seattle-based ZymoGenetics from its partner Bayer HealthCare Pharmaceuticals, which is supporting the launch of Recothrom in the U.S. for three years.

Under the collaboration, ZymoGenetics will compensate Bayer by paying a tiered commission of up to 20 percent on U.S. sales and up to $20 million in bonus payments when certain U.S. sales levels are attained.

Wayne, N.J.-based Bayer in June acquired the rights to Recothrom in all markets outside the U.S. The firm is responsible for conducting any required clinical trials, securing regulatory approvals and commercializing the product in all areas outside the U.S. (See BioWorld Today, June 20, 2007.)

ZymoGenetics CEO Bruce Carter noted Thursday during a conference call that Recothrom is the first product to be developed and commercialized by his firm.

"We believe that Recothrom offers important benefits undergoing surgery, and for us, the approval is a key milestone in the process of ZymoGenetics becoming a profitable, product-driven biotechnology company," he told investors and analysts.

The clinical development and regulatory process from investigational new drug application to approval for Recothrom took only four years, Carter said.

"An impressive accomplishment for any company, but I think even a greater one for a company like ZymoGenetics that has done it for the first time," he declared.

Douglas Williams, ZymoGenetics' chief scientific officer, said Recothrom is "broadly indicated for use as an aid to hemostasis without limitation to any type of surgery or method of application."

The product's labeling has no adverse reactions deemed related to Recothrom, he insisted.

"There is no black-box warning, there is no warning related to the potential transmission of infectious agent, as is found on all of the competing products containing plasma-derived thrombin, and there is a clear delineation of the statistically significant lower immunogenicity of Recothrom vs. bovine thrombin," Williams said.

The FDA's approval letter to the firm stated that the evaluation of the safety data in Recothrom clinical studies "did not reveal unexpected issues in this class of products," Williams added.

Further, he said, the letter stated that the study design to evaluate efficacy of Recothrom was "adequate and well controlled, and the results of the study did not raise any concerns related to safety or efficacy."

Williams noted that the approval for Recothrom is for the 5,000-unit-vial size and that the firm is seeking approval of a 20,000-unit-vial size and a topical spray kit. ZymoGenetics expects to receive approval on the larger vial size and topical spray kits by May, he added.

The 5,000-unit vials will be available to hospitals within the next two weeks, Williams said.

Michael J. Dwyer, ZymoGenetics' senior vice president of sales and marketing, said his firm's marketing research shows that hospitals are "eager to adopt" Recothrom as their "preferred topical hemostat."

In a study of 411 patients undergoing various surgical procedures, Recothrom met the primary indicator of effectiveness, which was control of bleeding within 10 minutes, the FDA said in a statement.

The product also was evaluated on secondary indicators of effectiveness, which were control of bleeding within three and six minutes.

"These measures of Recothrom's effectiveness were not inferior to ones displayed by the study's active control, a licensed topical thrombin derived from cattle plasma," the FDA concluded.