Zinbryta (daizumab) was flagged by European regulators with a lethal safety warning over cases of encephalitis and meningoencephalitis. Evaluating the drug’s “complex and evolving benefit/risk profile… will not be possible going forward given the limited number of patients being treated,” the companies said.

Al Sandrock, Biogen

The withdrawal is in patients’ best interests, said Biogen Chief Medical Officer Alfred Sandrock. Zinbryta, which the companies said is generally used in patients who have tried two or more other multiple sclerosis medications unsuccessfully, is currently sold in the U.S., where it was approved in May 2016, along with Europe, Switzerland, Canada and Australia. Earlier this year, restrictions to minimize risk of serious liver injury with Zinbryta were adopted in Europe. The European Medicines Agency investigated the reports of inflammatory encephalitis and meningoencephalitis, two kinds of brain inflammation typically caused by infection; those and other safety issues like liver toxicity, hypersensitivity reactions and inflammatory/immune toxicity have limited the drug’s profitability “in the context of a number of better options for the disease,” said RBC Capital Markets analyst Brian Abrahams.

Zinbryta has been the least profitable of Biogen’s stable of multiple sclerosis drugs, bringing in just $12 million in sales in the fourth quarter, about $53 million in global revenue last year and about $8 million the prior year. AbbVie and Biogen “essentially split profits” on the therapy, according to Abrahams, and Zinbryta revenues aren’t broken out in AbbVie’s financial results, which list only key product revenues.

Encephalitis is brain inflammation. In meningoencephalitis, there are features of both encephalitis and meningitis. Meningitis is inflammation of the membranes (meninges) that surround the brain and spinal cord.