Natalizumab Safe Up to 8 Weeks for Multiple Sclerosis

Extending the dose of natalizumab from 4 to 8 weeks was well tolerated and safe in multiple sclerosis (MS) patients, according to a poster presentation displayed at the American Academy of Neurology Annual Meeting held April 18-25 in Washington, DC.

Researchers from NYU Langone Medical Center and New York University School of Medicine retrospectively observed nearly 2,000 MS patients in order to evaluate risk of increasing the treatment period of natalizumab. The researchers noted that natalizumab is highly effective treatment for management of MS but it has limited use due to the susceptibility of patients to progressive multifocal leukoencephalopathy (PML). MS patients from 6 centers were split into 4 groups: standard dosing, early extended dosing, late extending dosing, and variable extended dosing. There were 1,078 patients taking a standard 4 week dose and 886 taking an extended dose between 4 weeks and 3 days and 8 weeks and 5 days.

The researchers determined that when the natalizumab dosing schedule was increased between 5 and 8 weeks, the drug’s efficacy profile was not effective. About two-thirds of participants in each group did not show clinical MS disease activity, the researchers said. There were comparable rates of new lesions reported on brain imaging across the groups.

“There remains much unknown about whether the drug will lose effectiveness if dosing is extended,” explained study leader Lana Zhovtis-Ryerson, MD, an assistant professor of neurology at the NYU Langone Multiple Sclerosis Comprehensive Care Center. “Our study showed treatment with natalizumab was safe for patients with similar efficacy reported as the standard dosing, potentially enabling patients to stay on effective MS medication at a reduced frequency of infusions and with lower risk of PML.”

The researchers reported no cases of PML in the extended dosing group, and 2 cases were reported in the standard dosing group. The researchers said, however, that the statistical significance had not yet been reached. There were no other adverse events documented.

“While the findings are encouraging, more research is needed to determine whether extending natalizumab dosing may reduce disability progression,” concluded Zhovtis-Ryerson in a press release.

Natalizumab is manufactured by Biogen Idec and Elan and sold under the brand name Tysabri.