West Coast Editor

The citizen petition filed with the FDA by Insmed Inc. against Tercica Inc. is either a last-ditch effort to hold a would-be competitor at bay, or a simple voicing of concern to regulators about a drug that might be unsafe.

Brisbane, Calif.-based Tercica - along with analyst Christopher Raymond, of Robert Baird & Co. in Chicago - believes the former scenario is the true one. And worse.

In a research note, Raymond wrote that the petition is "little more than a transparent attempt to derail" approval of Increlex (recombinant human insulin-like growth factor-1), a therapy for short stature that has a PDUFA date of Aug. 31.

John Scarlett, president and CEO of Tercica, called Insmed's move an abuse of the FDA's citizen-petition process, which lets private citizens or corporations outline a problem the agency should fix, explain why, and propose a solution.

Lester Crawford, head of the FDA, has publicly criticized such abuses, he added.

"It's become, unfortunately, a pretty common battleground for generics vs. pioneer companies," Scarlett told BioWorld Today. "This must be quite unusual, for two pioneers fighting it out, to have one of the competitors to seek to delay or deny approval."

Insmed, of Richmond, Va., has SomatoKine, composed of recombinant human IGF-I and IGF-binding protein-3, which is pending approval with the FDA for the same indication. In the race to market, Insmed was hobbled by the pushback of its PDUFA date to Oct. 3 from July 3, after the company added more safety data to the application.

The new drug application for SomatoKine was filed more than seven months ago, about the same time that Insmed disclosed the patent-infringement lawsuit brewing with Tercica and licensor Genentech Inc., of South San Francisco. (See BioWorld Today, Jan. 5, 2005.)

In the citizen petition, Insmed's safety concerns about Tercica's drug relate to hypoglycemia, and the petition says Tercica is asking for approval of Increlex for severe primary IGF deficiency (IGFD) with data that were generated in a different patient population, i.e., growth-hormone insensitivity syndrome (GHIS).

"There wasn't anything new in it," Scarlett said.

Raymond noted that hypoglycemia "has long been known to affect children treated with rhIGF-I therapy," but no children dropped out of Tercica's trial program as a result of it. Also, Insmed claims adverse events were under-reported by Tercica, and cites data made public in June 2004. Raymond wrote that he found it "curious" Insmed "only now discovered this supposed issue" - which, in any case, was remedied by giving Increlex before a meal.

Still, according to the petition, the FDA "must deny approval of Increlex, because Tercica's investigations do not adequately address the risk of hypoglycemia and other [adverse events] associated with rhIGF-I in the treatment of severe primary IGFD."

Insmed claims in the petition that Increlex should be approved only for GHIS, if anything, and not IGFD. But Tercica has done research to show the equivalence of the two conditions, Raymond wrote, and "patients treated by Increlex were actually IGF-I deficient."

Increlex and SomatoKine have been granted orphan status by the FDA, giving the first one approved seven years of market exclusivity.

The situation recalls the race between Cambridge, Mass.-based Genzyme Corp. and Transkaryotic Therapies Inc., also of Cambridge, to get first approval for a Fabry's disease therapy. Genzyme had Fabrazyme (agalsidase beta) running against TKT's Replagal (agalsidase alfa). The FDA ultimately gave clearance to Genzyme's drug. (See BioWorld Today, Jan. 14, 2004.)

Scarlett said the FDA must respond to a citizen petition within 180 days and "has a tremendous amount of latitude here. It does not have to be a definitive response." The agency could approve Increlex on the PDUFA date and deal with the petition later, he said, declining to speculate on what the agency might do.

"Nothing good comes from that," he said, adding that the FDA has been "extremely thoughtful, very professional" in all interactions with Tercica so far.

Tercica's stock (NASDAQ:TRCA) closed Thursday at $8.42, down 16 cents. Insmed's shares (NASDAQ:INSM) ended the day at $1.21, up 1 cent.

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