Natalizumab potential for Crohn's downplayed

The Boston Globe reports that it is unlikely that natalizumab (marketed as Tysabri) will be a viable treatment for Crohn's disease. Earlier reports had looked promising.

Biogen Idec's chief executive, James Mullen, says the Cambridge biotechnology company is unlikely to receive approval from European regulators to use its drug Tysabri to treat patients with Crohn's disease, a debilitating intestinal ailment.
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In a comprehensive safety review last year, the companies found two multiple sclerosis patients with PML who were also being treated with Biogen Idec's drug Avonex, another treatment for multiple sclerosis. One of those patients survived. Another patient in a Crohn's trial, who died from PML, had been treated with immunosuppressants.

That pattern suggested the risks of contracting PML while using Tysabri could increase if a patient is also being given a drug that affects the immune system. If so, that raises the risks of treating Crohn's patients with Tysabri, because many have weakened immune systems.

"Against the backdrop of PML, where you have a set of patients that already get bombarded with immunosuppressants over 20 to 30 years, [Crohn's] is not the first place we'd go to develop Tysabri," said Mullen. He said the drug looks more promising as a treatment for Lupus and certain cancers.

CBC News has further details from a north American perspective:

Caroline Stewart, an industry analyst for Piper Jaffray, said it would be difficult for Biogen Idec and Elan to match sales of the leading Crohn's treatment, Johnson & Johnson's Remicade, given Tysabri's PML risk.

"I think the sales in Crohn's are going to be limited, because it's not a life-threatening disease, and the potential side effects of Tysabri are life-threatening," Stewart said.