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six people had serious cases of ITP, a disorder in which the immune system goes haywire, attacking platelets, which are critical for blood clotting. That can make patients dangerously susceptible to bleeding episodes. Patients on Campath can also become vulnerable to infections, according to the drug’s prescribing information.
Genzyme’s current trials are monitoring patients’ blood samples, and performing regular phone calls to keep close watch on any dangerous side effects, Murdock said. The monitoring takes some extra effort, because patients don’t have to come see the doctor regularly to get treatment with the drug. Campath is designed to be given as an intravenous infusion daily for five days, then patients can take a year off, and get annual boosts, Murdock said.
Murdock wouldn’t say how much Genzyme is investing in the Phase III clinical trials, but it’s clearly a lot of cash. The first trial, in 525 patients, looks at patients who are new to MS treatment. The second study, of 1,200 patients, will test the drug among patients who have had prior therapy. “It’s one of the top priorities for the company, and it’s being adequately resourced,” Murdock says.
For its part, Biogen has a lot riding on getting the most mileage possible out of Tysabri. The company has forecasted it will have 100,000 patients taking the drug by the end of 2010, which would generate $2.8 billion annually at current prices. (Avonex, currently Biogen’s biggest-selling product, had $1.87 billion in sales in 2007, almost 60 percent of the company’s total revenue.) But Tysabri still hasn’t entirely stepped out from under the shadow of PML, the rare, fatal brain infection that has been associated with the drug and led it to be pulled from the market in 2005. Biogen brought the drug back to the market in July 2006 under a stringent monitoring program. No new cases of PML have been reported since, the company has said.
Each passing day without a new PML case makes Tysabri stronger, yet Biogen certainly can hear footsteps from its neighborhood rival. Campath’s efficacy numbers appear so far to be better than Tysabri’s, which is shown to reduce the risk of MS flare-ups by two-thirds. Campath and another experimental drug from Basel, Switzerland-based Novartis, FTY-720, “may offer patients greater efficacy, but there is greater risk than first-generation therapies,” said Biogen spokeswoman Shannon Altimari in an e-mail. “The risk-benefit of these therapies will have to be taken into consideration.”
To date, MS patients on Campath haven’t had any reported cases of PML. If that holds, and if the current studies of the drug are as successful as the earlier ones, Genzyme could end up taking a large bite out of Biogen’s biggest moneymaker.