FDA Rejects Under-the-skin Tysabri for Relapsing MS

The U.S. Food and Drug Administration (FDA) has rejected Biogen‘s request for approval of under-the-skin administration of Tysabri (natalizumab) as a treatment for relapsing forms of multiple sclerosis (MS).

“This response from the FDA does not affect the intravenous administration of Tysabri, a well-established high-efficacy treatment with a well-characterized safety profile, which over the last 15 years has treated more than 200,000 people worldwide with relapsing MS,” Maha Radhakrishnan, MD, chief medical officer at Biogen, said in a press release.

While the content of the FDA’s complete response letter, and the reasons behind the decision were not disclosed, the regulatory agency was “unable to approve the company’s filing as submitted,” the company wrote. Biogen is reviewing the letter and considering its next steps in the United States.

Tysabri is an antibody that reduces nerve damage by preventing certain immune cells from reaching the brain and spinal cord, where they can trigger inflammation that damages the myelin sheaths protecting nerve fibers.

The therapy is approved in the U.S. for relapsing forms of MS, as an intravenous (into-the-vein) infusion every four weeks. This infusion is normally given over one hour, and requires that patients remain in observation for another hour after infusion is complete.

The proposed under-the-skin, or subcutaneous, method would be an alternative to the standard intravenous infusion that can be administered in less time. It also would enable Tysabri to be administered in settings beyond infusion centers and would involve shorter post-dosing safety observation periods.

The recent application was based on data from the DELIVER (NCT00559702) and REFINE (NCT01405820) clinical trials, which compared the subcutaneous and intravenous formulations of Tysabri in about 350 people with RRMS and secondary progressive MS.

Results showed the two formulations were similar in their efficacy, safety, pharmacokinetic, and pharmacodynamic profiles — that is, how the medication moves through the body and how it affects the body.

The European Commission recently approved subcutaneous Tysabri for relapsing-remitting MS (RRMS) based on these findings. Biogen also plans to apply for regulatory approval of this method in several other countries.

“We are committed to MS and pursuing innovations such as new routes of administration to help provide options that could address the individual needs of patients,” Radhakrishnan stated.

Recently, a study found that Tysabri improved the mental and social health measures of patients, such as depression and anxiety. A separate study revealed that a less-frequent dosing regimen — every six weeks — reduced patients’ risk of rare brain infections, while still lessening MS activity.

Both studies were presented at the recent 2021 Virtual American Academy of Neurology Annual Meeting.