Extending Dose of Multiple Sclerosis Drug Safe and Effective

Pushing treatment with natalizumab from 4 weeks up to 8 weeks shows promising results.

Extending therapy with an infusion drug in the treatment of multiple sclerosis (MS) was found to be safe and effective during a recent clinical trial.

The results of the trial, which were presented at the American Academy of Neurology annual meeting, found that extending the dose of the monoclonal antibody natalizumab from 4 weeks up to 8 weeks was well-tolerated and effective. Extending use also did not result in any cases of the potentially fatal side effect progressive multifocal leukoencephalopathy (PML).

“There remains much unknown about whether the drug will lose effectiveness if dosing is extended," said study lead Lana Zhovtis-Ryerson, MD, in a press release. "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.”

Natalizumab is prescribed in 300-milligram infusions every 4 weeks for the prevention of MS symptoms and flare-ups and to inhibit worsening disability. Using the medication for more than 2 years, however, can increase the risk of PML, a rare and untreatable brain infection that occurs in up to 1.3% of patients taking the drug.

The study evaluated the safety and efficacy of an extended dose of natalizumab to the standard dose by retrospectively comparing 1078 patients on a standard 4-week dose with 886 patients taking an extended dose between 4 weeks, 3 days, and 8 weeks, 5 days.

The results showed that extending the use of natalizumab to between 5 and 8 weeks does not impact efficacy, as 65% of patients in each group did not show clinical MS activity. There were comparable rates of new lesions reported on imaging.

Meanwhile, there were not any cases of PML reported in the extended dosing arm, but there were 2 cases found in the standard dose arm. The researchers noted that the statistical significance has not yet been reached and there were no other major adverse events reported.

"While the findings are encouraging, more research is needed to determine whether extending natalizumab dosing may reduce disability progression," Dr. Zhovtis-Ryerson said.