Rival rips drug of Seattle biotech

A biotech rival has asked federal regulators not to approve ZymoGenetics' lead product, citing concerns about insufficient testing.

The petitioner, King Pharmaceuticals of Bristol, Tenn., said in a statement the Seattle company is seeking a quicker-than-normal pathway for the approval of rThrombin, a biologically engineered product to control surgical bleeding.

A blessing from the Food and Drug Administration would be "contrary to law and agency precedent," the petition said.

King manufactures a competing version of the product.

rThrombin is set to be ZymoGenetics' first commercial launch, potentially sending the company on the path of profitability by contributing hundreds of millions in sales.

King made the request through a so-called "citizen petition" with the FDA, a common delaying tactic in the no-punches-pulled world of biotechnology.

If the motion succeeds, King could gain valuable time and market share while undermining a rival's product. But such requests are often dismissed by the agency. The FDA declined to comment on the petition.

"King is really threatened because they make a fairly large amount of money from thrombin," said Seattle analyst Paul Latta of McAdams Wright Ragen. "They're trying to take measures to protect their business."

An FDA decision to heed King's complaints would be a major setback for ZymoGenetics, Seattle's largest independent biotech. ZymoGenetics had expected the FDA to approve rThrombin in October, but the agency extended the deadline to Jan. 17 to study manufacturing data.

While King's attack adds some uncertainty to ZymoGenetics' timeline, "the company has been working with the FDA for years on this particular protein," said Latta. "I'd just find it difficult to believe that this would be somehow against protocol at this stage."

rThrombin, which would be marketed by pharmaceutical juggernaut Bayer, represents a challenge to thrombin products made by both King and New York-based Omrix Biopharmaceuticals.

A research note by Alex To, of investment bank Natixis Bleichroeder, said ZymoGenetics' artificial thrombin carries less immunological risk than its competitors, which have human and bovine origins.

King, which asserts ZymoGenetics hasn't collected enough safety and efficacy data in its clinical trials, also asks the FDA to bar labeling "that would allow comparative superiority claims, unless those claims are substantiated by evidence from adequately powered comparative clinical trials."

ZymoGenetics shares held their ground Thursday, despite the King move and a major drop in the stock market. The stock closed at $13.42, down 0.22 percent. King shares fell 1.70 percent to $10.42.

Ángel González: 206-515-5644 or agonzalez@seattletimes.com