MBI claims another victory over Sonus after ruling on ultrasound contrast patents

Sonus prepares to appeal patent rejection

Ultrasound contrast firm Sonus Pharmaceuticals was dealt another setback this month by the U.S. Patent Office, which ruled that two of the company's patents for contrast technology are invalid. If the ruling stands, it could make it much more difficult for Sonus to pursue its patent infringement claims against arch-rival Molecular Biosystems.

The Sonus patents cover the use of perfluorocarbon gases as an ultrasound contrast agent. MBI has asserted that the technology is not patentable on prior art grounds: Information about the technology existed in the public domain before the patents were granted. The Patent Office apparently agreed with MBI's position.

Despite the apparent setback, Sonus of Bothell, WA, plans to fight the action. Although MBI characterized the ruling as the PTO's final word on the issue, Sonus believes it still has recourse to an appeal.

"We have an opportunity to reply to that office action and that is our intention," said Sonus spokesperson Kelly Ford. "We plan on responding with scientific data to show what is called unexpected results when compared with prior art. Then the PTO will have an opportunity to respond to that new information, and we will go from there."

Sonus has stated that its patents cover MBI's Optison, which the FDA approved in December to enhance left ventricular opacification (SCAN 1/14/98). The product is now being marketed in Europe and the U.S. by Mallinckrodt of St. Louis.

MBI filed the re-examination actions with the PTO to derail the possibility that Sonus could use its patents to stop MBI and Mallinckrodt from selling Optison. MBI filed similar actions against five patents held by two other companies, Nycomed Amersham and ImaRx Pharmaceutical.

Since those requests were filed, the PTO has issued "office actions" rejecting all relevant claims of the five patents, citing the existence of prior art, which includes drawings, text, or other information that describes the process before a patent application was submitted. The PTO has rendered final rejections only in regard to the two Sonus patents.

But "final," apparently, is a relative term. Sonus plans to submit a response to the PTO decision in the near future, according to Ford, although exactly when is not known.

"The timing of our response is really dependent on several factors, including the patent examiner himself and how he wants to proceed," Ford said.

If Sonus mounts this appeal as expected, the issue might not be settled for months or even years. By then, the patents might not be relevant, according to Bob Giargiari, director of investor relations at San Diego-based MBI.

"We (the industry) could all be working on the seventh generation of products by the time these patent issues are cleared up," Giargiari said.

Another uncertainty is how the PTO action and the Sonus response will affect a patent infringement suit filed by Sonus against MBI. Neither company was aware of any change in the status of the case, which apparently is still pending in a U.S. District Court in Seattle. But MBI is not necessarily satisfied with the status quo.

"We are looking at a number of different options to make this thing go away in one way or another," Giargiari said.

One option is to argue that Sonus cannot sue MBI for infringement if the patents are not valid. MBI then might ask for a stay of all proceedings until the patent matter is resolved. This could delay the case indefinitely.

Another option is to try to have the case dismissed. This second option is less attractive, Giargiari said, because Sonus could appeal if the judge decides to throw out the case.

"We are still evaluating how we will proceed on this," he said.