First FDA-Approved Biosimilar for Multiple Sclerosis Mimics Tysabri

On August 24, 2023, the United States Food and Drug Administration approved Tyruko, natalizumab-sztn, a biosimilar for Tysabri (natalizumab), an injectable biologic for managing multiple sclerosis. The drug has also been indicated to manage moderate-to-severe Crohn’s disease (CD) for patients with inflammation who have not responded to other treatment alternatives.

The new approval expands indications to include multiple forms of relapsing multiple sclerosis, including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease.

“Biosimilar medications offer additional effective treatment options that have the potential to increase access for people living with relapsing forms of multiple sclerosis,” said Paul R. Lee, MD, PhD, director of the Division of Neurology Two in the FDA’s Center for Drug Evaluation and Research, in the FDA press release. “Today’s approval could have a meaningful impact for patients managing their disease.” 

Multiple sclerosis is an autoimmune disease that causes chronic inflammation in the central nervous system. Although the condition can impact anyone, it is more common in women than men. Multiple sclerosis can manifest as numbness, tingling, memory issues, pain, fatigue, blindness, muscle weakness, cognitive impairment, and mood changes.

“Today’s approval of the first biosimilar product indicated to treat relapsing forms of multiple sclerosis furthers the FDA’s longstanding commitment to support a competitive marketplace for biological products and ultimately empowers patients by helping to increase access to safe, effective, and high-quality medications at potentially lower cost,” added Sarah Yim, MD, director of the Office of Therapeutic Biologics and Biosimilars in the FDA’s Center for Drug Evaluation and Research. 

Despite the newly approved uses for this biosimilar, the FDA still advises caution with these drugs. Healthcare professionals and patients should be aware of an increased risk of progressive multifocal leukoencephalopathy (PML). Prior use of immunosuppressants, extended therapeutic duration, and the presence of anti-JVC antibodies can also exacerbate the risk of PML.

Other potential adverse effects include low blood platelet counts, immunosuppression, anaphylaxis, hepatotoxicity, headache, and fatigue.

Considering the potential adverse effects of these biologic products, the FDA only allows these products to be dispensed via a restricted drug distribution program with a risk evaluation and mitigation strategy (REMS).