Serious side effects of a commonly-prescribed multiple sclerosis (MS) drug could be reduced by extending dosing intervals, according to researchers at NYU Langone Health. The findings of the study – presented at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2018 – could change the way neurologists prescribe the medication to patients with MS.
“Neurologists have been looking for safer ways to administer natalizumab infusions to their patients, but there hasn’t been clear data on whether decreasing dosing frequency improves safety,” said first study author Dr. Lana Zhovtis Ryerson, assistant professor of neurology at NYU School of Medicine and an attending neurologist at NYU Langone’s Multiple Sclerosis Comprehensive Care Center. “Our safety findings are clinically and statistically significant, and we believe that extending the dosing schedule of natalizumab is practice changing and may save lives.”
Ryerson and her colleagues found that extending dosing of natalizumab – a disease-modifying therapy for MS – from every four weeks to every five to 12 weeks, they were able to reduce the risk of a rare brain infection known as progressive multifocal leukoencephalopathy (PML), which can be fatal. The monoclonal antibody is currently prescribed at a dosage of 300 mg every four weeks to prevent relapses and slow the progression of MS.
However, previous studies have found that patients taking the medication for more than two years may be at an increased risk of developing PML. The global incidence rate of PML in MS patients taking natalizumab is 4.19 in 1,000, however only 756 cases of the brain infection have been reported as of the start of 2018.
Caused by the John Cunningham virus (JCV), PML is a risk in patients on long-term therapy with natalizumab. MS patients are usually tested for JCV antibodies prior to starting treatment with natalizumab, and positive results could prompt doctors to stop giving the antibody after two years, or make a patient ineligible for treatment with the disease modifying therapy altogether.
However, the extended dosing regimens assessed in the current study showed risk reductions for PML up to 94 percent over a six-year study period. Previous research suggests this strategy would not negatively affect the efficacy of the drug, potentially allowing patients with MS to benefit from natalizumab without the risk of developing the deadly PML.
Natalizumab is sold under the name Tysabri and manufactured by Biogen Idec, who provided the data for this study. Biogen Idec acquired the rights to the MS drug in 2013 from neuroscience-focused biotech company, Elan.