Biogen Idec PML Test Approved in Europe,
Changing Tysabri Outlook


March 15, 2011

For all the publicity about multiple sclerosis drug Tysabri, investors tend to forget that the real breadwinner so far for Biogen Idec continues to be Avonex, also for multiple sclerosis (MS). Avonex revenues in Q4 2010 were $654 million; Tysabri revenues were $242 million.

Tysabri is the more effective drug, but it has been held back by the risk of PML, progressive multifocal leukoencephalopathy. This is in turn caused by JCV, a virus often quietly, apparently harmlessly residing in human brains. MS is an immune disorder; its treatments involve dialing down the immune system. In about 1 in 1000 patients, JCV wakes up, and instead of being taken care of by the immune system, causes serious damage or even death.

As a result, despite its effectiveness many patients and doctors have only used Tysabri as a last resort.

Now that score should change. The new test will let physicians know which MS patients have JCV and which don't. Presumably, those that don't have JCV could take Tysabri without fear. It is believed that about one-half of potential patients in the U.S. and Europe have JCV, although it is more common in cultures with poor sewage systems.

Those who have JCV can still take Tysabri, but would be closely monitored. So far PML incidents have occurred in patients taking Tysabri for a period longer than 1 year.

New MS therapies are also being developed or marketed, notably Gilenya by Novartis, which is the first oral treatment for the disease, but which was not as effective as Tysabri in clinical trials.

Meanwhile, Biogen is narrowing the scope of its development program, eliminating oncology and cardiovascular candidates to focus on immunology. This should reduce costs in the short run.

Since the quarter ended Fampyra for mobility for MS patients was rejected by the European Medicines Agency (EMA), but Biogen is appealing the decision. Fampyra is approved in the United States. The FDA also approved Rituxan as a maintenance treatment for advanced follicular lymphoma. In the quarter Rituxan generated $258 million.

Because Tysabri can now be "risk stratified," Biogen has stopped enrolling patients in the long-term Surpass trial, which is designed to show off its superior efficacy.

Going forward, Biogen has a lot riding on the questions of whether doctors and patients can put the PML scare behind them, and on whether they will prefer an easy to administer oral drug to the more effective, but harder to administer Tysabri.

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William P. Meyers


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Copyright 2011 William P. Meyers