Washington Editor

Lilly ICOS LLC said it intends to "vigorously defend itself" against a claim by Pfizer Inc. that its erectile dysfunction candidate, Cialis, infringes on Pfizer's patent that protects the blockbuster drug, Viagra.

The message comes a day after the U.S. Patent and Trademark Office issued New York-based Pfizer a patent for "pyrazolopyrimidinones for the treatment of impotence." On receiving the patent, Pfizer filed lawsuits in the U.S. District Court in Delaware against Lilly ICOS, and Bayer AG, of Leverkusen, Germany, and its partner, GlaxoSmithKline plc, of London, for their sexual dysfunction product, Levitra.

"In general, the patent describes chemical agents of specific composition used for treating erectile dysfunction," according to research notes released by Bill Tanner, managing director of Leerink Swann & Co. in Boston. "The lawsuits are intended to enjoin development and commercialization of the companies' respective small-molecule, PDE5 inhibitor, male erectile dysfunction drug candidates, Cialis and Levitra."

Cialis and Levitra are late-stage development products on track for U.S. approval during the second half of 2003.

Similar to the prepared statement released by Lilly ICOS, Patty Seif, a spokeswoman for GlaxoSmithKline in Philadelphia, told BioWorld Today that Bayer and GSK intend to "vigorously defend ourselves" against the Pfizer suit.

The companies do not expect the Pfizer lawsuit to impact the regulatory process.

In fact, Lacy Fitzpatrick, director of investor relations for Bothell, Wash.-based ICOS, told BioWorld Today, "We do not think this will delay development because the PTO and the FDA work separately."

Lilly ICOS LLC is a joint venture between ICOS Corp. and Eli Lilly & Co., of Indianapolis, formed for the development of Cialis.

Last year the European Patent Office and the UK Court of Appeals ruled in favor of Lilly ICOS on a similar dispute with Pfizer regarding a "method of use" patent for ED products, Fitzpatrick said.

"Pfizer could claim that the U.S. PTO issued the patent yesterday with the knowledge that the European Patent Office had overturned it," Tanner told BioWorld Today. "Pfizer could claim that if the patent looked like it could be invalid, the PTO wouldn't have approved anyway."

There are a number of ways this lawsuit could end, Tanner said. "If they go to trial, I would have to believe that Pfizer is not going to get an injunction, that Lilly ICOS would still be able to launch Cialis. If it is found that they did infringe, maybe Lilly ICOS would have to pay some damages."

Whether such a lawsuit could end in Cialis or Levitra being pulled from the market, or never making it to market, remains a decision of the courts.

"If you are looking at a drug that would treat a life-threatening disorder, it would probably be unpopular to take it off the market," Tanner said. "But for a male erectile dysfunction drug, there is another option." That option is Viagra.

Viagra, a billion-dollar drug, gives men the ability to achieve an erection for up to eight hours after taking it. Tanner said Levitra is believed to be similar. However, there's something very different about Cialis - it could produce effectiveness for up to 36 hours. (See BioWorld Today, May 29, 2002.)

"I think the next drug to enter the market that is apt to be the most successful would be Cialis because it is a differentiated product," Tanner said. "The worst thing you could do, if you can imagine, is to develop a generic Viagra and go toe-to-toe with Pfizer and their 1,500 sales reps. Bayer has a drug that isn't a generic Viagra, but it looks a lot like Viagra."

He said Viagra will generate about $1.7 billion in revenue this year, but the ED market could grow to $3 billion, $4 billion or $5 billion over time.

"After Bayer and Lilly ICOS launch, the market could flatten a couple of years down the road, but Cialis being a $500 million to $1 billion global drug is certainly reasonable to contemplate," Tanner said.

The FDA in May issued an approvable letter for Cialis contingent upon additional confirmatory clinical pharmacology studies, labeling negotiations and resolution of Lilly's outstanding GMP manufacturing deficiencies. (See BioWorld Today, May 1, 2002.)

And in July, the FDA sent Bayer and GSK an approvable letter for Levitra (formerly vardenafil) saying the product could be approved after the companies conducted additional clinical pharmacology studies.