The US Food and Drug Administration (FDA) approved daclizumab (Zinbryta, Biogen/AbbVie) today for treatment of patients with relapsing forms of multiple sclerosis (MS), according to an FDA news release.

The agency cautions, however, that the drug should be used only in patients who have failed to respond to one or two prior therapies, as the new agent has serious safety risks, including potentially severe liver damage and immune conditions.

The drug is given by self-administered subcutaneous injection once a month.

"Zinbryta provides an additional choice to patients who may require a new option for treatment," said William Dunn, MD, director of the Division of Neurology Products in the FDA's Center for Drug Evaluation and Research, in the release.

Data from two clinical trials demonstrate daclizumab's effectiveness. In the DECIDE study, reported previously by Medscape Medical News, 1841 patients were randomly assigned to daclizumab 150 mg administered subcutaneously every 4 weeks, or to interferon β-1a (Avonex, Biogen) injected intramuscularly weekly. During the 144-week trial, patients treated with daclizumab had fewer clinical relapses than those treated with the interferon β-1a.

Similarly, in a 52-week, placebo-controlled trial (n = 412) called SELECT, patients treated with daclizumab had fewer relapses than those in the control arm.

The new label will contain a boxed warning, and daclizumab will be available only through a limited distribution program under a Risk Evaluation and Mitigation Strategy.

The boxed warning tells clinicians that the drug can cause severe, potentially fatal, liver injury. Patients' liver function should be tested prior to the first dose and before each monthly dose, and for 6 months after stopping the drug.

The warnings also caution that the drug can cause hypersensitivity reactions, including anaphylaxis or angioedema, can increase the risk for infections, and has been associated with symptoms of depression and/or suicidal ideation.

More common side effects seen in patients treated with daclizumab include "cold symptoms (nasopharyngitis), upper respiratory tract infection, rash, influenza, dermatitis, throat (oropharyngeal) pain, eczema, and enlargement of lymph nodes," the release notes.

Daclizumab is a humanized monoclonal antibody that selectively binds to the high-affinity interleukin-2 receptor subunit (CD25), which is expressed at abnormally high levels on T cells in patients with MS. The company has said in earlier press releases that the mechanism of action does not cause broad and prolonged immune cell depletion.

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