In its first weeks on the market, Biogen Inc.'s Avonex beta interferon is doing just what the company hoped: opening up new markets for the multiple sclerosis drug.

The drug hasn't yet made major inroads into established users of Berlex Labs/Chiron Corp.'s Betaseron. And the bulk of patients thus far don't appear to be coming from the major academic centers, many of which have a great deal of experience - and thus a high comfort level - with Betaseron. Nevertheless, even doctors at centers that are high-Betaseron users expect that the market for the two drugs will be split 50-50 a year from now.

Avonex posted $6.1 million in sales in its first six weeks on the market. Nine weeks after launch, there were 8,000 patients on the drug. BGEN estimates that about 50-60 percent of those users are naive patients - patients who have never been on Betaseron. Of the rest, BGEN doesn't yet know if they are switching from Betaseron or are dropouts from Betaseron, according to spokesperson Richard Lundberg. The company estimates that 25,000 patients have stopped taking Betaseron.

In the first two weeks of July, the company was adding 1,000 new patients a week. The volume of calls and the number of patient training kits sent out - which are "quasi-tied" to actual shipments - currently are tracking at the rates the company saw in July, said Lundberg.

BGEN estimates that its sales reps have contacted 70 percent of the neurologists who have prescribed Betaseron. But the high numbers of naive users indicate that patients are driving Avonex sales, said Lundberg. "The scrips we're seeing aren't all from folks who've previously prescribed Betaseron," he said. "It's a broader audience. It points to the fact that patients are pulling the product right now.

"You'll have patient XYZ in the middle of Pennsylvania - away from a center - who goes into the neurologist," said Lundberg. "That neurologist hasn't yet been visited by our sales reps because he hasn't previously prescribed Betaseron. The neurologist will say, 'if you want Avonex, fine.' So it may be that the patients on the drug may be less concentrated among Betaseron high prescribers and at the big centers."

This picture - of patients away from the major centers driving initial use of Avonex - fits with BioCentury's informal survey of clinicians, many of whom are at large MS centers. Most of those physicians have put only a few patients on Avonex.

The scenario also fits with what Kathy Costello, a registered nurse and clinical coordinator of the Maryland Multiple Sclerosis Center, is hearing anecdotally. "Among the community neurologists, Avonex is a pretty popular drug because it requires less management," said Costello. "They like what they read about progression, less depression, no lab abnormalities, etc. If I was out in the community with no support behind me, I'd be inclined to use it."

Lundberg expects the usage pattern will be a plus for Avonex, giving the drug a wide base. He noted that Schering AG, Berlex's parent, posted DM145 million in Betaseron sales in the second quarter, and stated that it hasn't seen an impact from Avonex. "That's good - it means we're expanding the market," he said. "It means there are plenty of Betaseron patients we can switch when we get to them. If a patient has an exacerbation on average every 10 months, you have a rolling population to target - people who are starting to have problems."

Hillel Panitch
Professor of neurology, University of Maryland and Maryland Multiple Sclerosis Center

Kathy Costello
Clinical coordinator, Maryland Multiple Sclerosis Center