Tysabri label change could add $1B to sales

Biogen Idec ($BIIB) has pulled off a big coup in personalized medicine. The multiple sclerosis drug Tysabri has long been weighed down by a well-known safety risk: It's linked with a potentially fatal brain infection, progressive multifocal leukoencephalopathy. Now, though, Biogen has won FDA approval to modify Tysabri's label with information on identifying the highest-risk patients. And the company has developed a diagnostic test to do just that.

As Bloomberg reports, the label change could add a full $1 billion to 2016 sales of the drug, which Biogen sells in partnership with the Irish drug company Elan. RBC Capital Markets analyst Michael Yee told the news service that Tysabri could hit $2.5 billion to $3 billion in revenues that year, compared with $1.5 billion to $2 billion without the change.

The Tysabri-PML saga is a long one, and it's been extraordinarily public. The drug was pulled from the market in 2005 after patients developed PML, and then reintroduced in 2006 with a boxed warning and risk-management plan. Biogen warned then that new PML cases were likely to surface, though the absolute risk was statistically quite low. When new cases cropped up, the company updated the numbers regularly.

Meanwhile, Biogen was looking for ways to determine which patients were most likely to develop PML, and researchers developed an algorithm to identify risk factors. One of those factors was exposure to the John Cunningham virus. Patients exposed to that virus proved more likely to develop PML than other patients. So, Biogen teamed up with Quest Diagnostics to develop an antibody test, which could identify those patients whose exposure could put them at higher risk of PML. Now, that test has FDA approval, and Tysabri has its new label flagging JCV antibodies as a risk factor.

"Our development of the risk stratification algorithm and subsequent efforts to support the commercial availability of anti-JCV antibody testing reflect our commitment to providing patients and their physicians with additional guidance to help them make more personalized treatment decisions," CEO George Scangos said in a statement.

- see the FDA release
- get the statement from Biogen
- see the story from Bloomberg
- read the Dow Jones piece

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