West Coast Editor

As many predicted, the FDA approved Biogen Idec Inc.'s multiple sclerosis drug Tysabri (formerly known as Antegren) as a combination and monotherapy for relapsing forms of the disease, but the company and partner Elan Corp. plc did not disclose pricing for the would-be blockbuster.

Analysts, though, are estimating sales of $2 billion or more, and forecasts on pricing start at about $20,000 per year. Competing MS products range between about $13,000 and $16,000 per year. Tysabri's cost will be disclosed this week, Biogen Idec said.

The company's shares (NASDAQ:BIIB) closed Wednesday at $58.59, up $1.16. Dublin, Ireland-based Elan's shares (NYSE:ELN) ended the day at $27.27, down 3 cents.

News about Tysabri gave MS patients and investors alike cause for giving thanks on the day before the holiday. Michelle Grady, senior analyst with Decision Resources in Waltham, Mass., said the MS market, by 2013, will more than double from its 2003 level, and Tysabri's competitors - which once took 98 percent of that market - will have less than half, with Tysabri accounting for fully a third.

"Physicians we spoke to are optimistic that this drug will end up being a mainstay in MS treatment," Grady told BioWorld Today.

Others were similarly optimistic. Jennifer Chao with Deutsche Bank Securities in New York hailed the "stellar data" and predicted a "major blockbuster," with a "buy" rating on the stock and Tysabri sales for 2005 estimated at $410 million.

The accelerated approval was based on single-year results from the AFFIRM monotherapy trial and the SENTINEL study, which combined Tysabri with Biogen Idec's MS drug Avonex (interferon beta-1a).

Data disclosed earlier from AFFIRM showed Tysabri reduced relapse rates by 66 percent compared to placebo, and top-line results from SENTINEL made public in conjunction with the approval indicate a 54 percent reduction in relapse rate for Tysabri plus Avonex vs. Avonex alone.

The only potential hitch - which might turn out to be its advantage instead - is Tysabri's intravenous route of administration. It's infused monthly, rather than injected more often.

"It's a tough thing [to predict]," Grady said. "I don't know if mild patients who tend to be younger women of childbearing age will be willing to go to an infusion center." On the other hand, she said, "if the drug really works, I don't think patients will care where they have to go."

Most MS patients currently get one of the beta interferons or Copaxone (glatiramer acetate), from Teva Pharmaceutical Industries Ltd., of Jerusalem. The former class includes Avonex; Rebif from Serono SA, of Geneva; and Betaseron, sold by Montville, N.J.-based Berlex Laboratories Inc.; and all four drugs are given either the subcutaneous or intramuscular route. Serono this month introduced a new 29-gauge needle with its Rebiject II device, said to make dosing even less painful and easier, with fewer site reactions.

Rebif is given three times per week subcutaneously, Betaseron subcutaneously every other day, Avonex intramuscularly once per week, and Copaxone subcutaneously daily.

Grady pointed out that, although Rebif has been "really chipping away at Avonex's patient share," the latter drug has been able to hang on because patients don't like to inject any more times than necessary.

"Convenience is a big factor, larger than we thought, for a chronic disease," she added, especially for patients with milder disease who can "go a pretty long time without that many symptoms."

Robert W. Baird & Co. in Chicago offered results from a recent survey showing that, although familiarity with the drug was widespread, only 17.3 percent of 98 freestanding, private-practice neurology clinics polled had IV capability or intended to get it soon. Asked how they intended to administer Tysabri, most said they would refer patients to hospitals.

Baird, while keeping its revenue estimate of $325 million for Tysabri in 2005, pointed out in a research note by Christopher Raymond that the drug's benefit to Biogen Idec's bottom line "could be more back-end loaded than we originally thought.

After the approval was disclosed, Raymond reiterated his dimmer view in another report.

"While head-to-head comparisons are difficult given different patient populations, we note that combination-treated patients showed a response rate similar to Tysabri monotherapy-treated patients (0.36 vs. 0.25, respectively)," he wrote. "Moreover, higher incidences of serious infections (61.5 percent increase over placebo) and persistent antibody formation (6 percent, comparable to Avonex) confirm that Tysabri therapy is not without risk."

Raymond's firm "still caution[s] that Tysabri's uptake may not be as fast as some may anticipate."

Biogen Idec and Elan changed the brand name of Antegren (natalizumab), an alpha-4 antagonist, by request of the FDA to prevent confusion with other drugs bearing similar-sounding names, an example of which could be the heart drug Integrilin (eptifibatide) from Cambridge, Mass.-based Millennium Pharmaceuticals Inc.

"As part of the review process, they took a look at the name and it's similar to some of the other products out there," said Amy Brockelman, spokeswoman for Biogen Idec, also of Cambridge. The new name is built around "abri," which means "shelter" in French, and is meant to convey "a sense of protection," she said.