Conference Coverage

Extended-interval dosing of natalizumab linked to lower risk of PML


Key clinical point: Extended-interval dosing of natalizumab appears to lower the risk of progressive multifocal leukoencephalopathy (PML), compared with standard-interval dosing in patients who showed signs of exposure to the JC virus.

Major finding: Estimated incidence of PML per 1,000 patients was 1.23 in an extended-interval group and 3.96 in a standard-interval group among those who had received 49-60 natalizumab doses.

Study details: 18-month analysis of multiple sclerosis patients on natalizumab who showed signs of exposure to the JC virus: 1,988 on extended-interval dosing and 13,132 on standard-interval dosing.

Disclosures: The study was funded by Biogen, and multiple study authors report being employees of Biogen or having other relationships to the company.

Source: Zhovtis R et al. ACTRIMS Forum 2018, Abstract LB250.



– A large industry-funded study of the multiple sclerosis drug natalizumab suggests that physicians can dramatically lower the likelihood of progressive multifocal leukoencephalopathy in patients at higher risk of the condition by increasing the interval between doses.

Previous research has suggested that natalizumab (Tysabri) doesn’t lose efficacy when given less frequently.

Dr. Lana Zhovtis Ryerson

Dr. Lana Zhovtis Ryerson

“Although further sensitivity analysis needs to be done to assure that the conclusions are correct, we feel that this approach may be practice changing as it shows a potentially safer way to administer a highly effective medication,” study lead author Lana Zhovtis Ryerson, MD, of New York University said in an interview.

Dr. Zhovtis Ryerson presented the study findings at the meeting held by the Americas Committee for Treatment and Research in Multiple Sclerosis.

As a 2014 report explains, natalizumab is a “highly effective disease-modifying therapy for the treatment of relapsing forms of multiple sclerosis,” but the risk of progressive multifocal leukoencephalopathy (PML) “has largely contributed to it being relegated to a second-line position” (Ther Adv Chronic Dis. 2014 Mar;5[2]:62-8).

Patients previously exposed to John Cunningham (JC) virus are at higher risk of PML, a rare viral brain disease that can be severely disabling or deadly. A 2017 report estimated the combined cumulative PML probability at 2.7% (with previous immunosuppressant use) and 1.7% (no previous immunosuppressant use) over 6 years in patients with signs of exposure to the JC virus (Lancet Neurol. 2017 Nov;16[11]:925-33). According to Dr. Zhovtis Ryerson, natalizumab manufacturer Biogen reported in December 2017 that it has confirmed 756 cases of PML in natalizumab-treated patients, all except for 3 in MS patients.

Doctors are wary in the at-risk patient population. “In general,” she said, “clinicians treating patients who are JC virus positive, and therefore have a risk for PML, may not utilize the drug or may take the patient off it after 2 years, which is when the risk goes up.”

Some physicians have experimented with longer intervals between treatments of 300 mg given intravenously, administering it every 5-8 weeks instead of every 4 weeks, with an eye on not extending the interval for too long “because MS disease activity returns after 12 weeks of withholding therapy,” Dr. Zhovtis Ryerson said.

In 2016, Dr. Zhovtis Ryerson and colleagues reported in a retrospective analysis that natalizumab dosing intervals of up to 8 weeks, 5 days didn’t affect the drug’s efficacy (J Neurol Neurosurg Psychiatry. 2016 Aug;87[8]:885-9).

For the primary analyses in the new study – whether dosing history in the last 18 months of natalizumab treatment affects PML – researchers tracked 1,988 patients who took the drug via an extended interval schedule and 13,132 who took it via a standard interval. The patients were tracked in the mandated TOUCH Prescribing Program; all participants showed signs of exposure to the JC virus.

The two groups were similar at about 68% female, an average age at first infusion of about 43, and a median number of about 48 natalizumab infusions.

For patients without previous immunosuppressant use who had received 49-60 doses, the researchers estimated the incidence of PML per 1,000 patients as 1.23 in the extended-interval group and 3.96 in the standard-interval group. The numbers were slightly higher for those who received 61-72 doses. At 48 or fewer doses, there were no PML cases in patients on extended-interval dosing.

“The data showed highly significant risk reductions of up to 94%,” Dr. Zhovtis Ryerson said.

Moving forward, “in collaboration with Biogen, we have more sensitivity analysis to be done to assure that our conclusions on this are correct,” she said. “Furthermore, more evidence of efficacy of extended-interval dosing natalizumab is needed, and we hope to move forward with a prospective, randomized, controlled trial to give clinicians the highest level of evidence we can.”

The study was funded by Biogen. Dr. Zhovtis Ryerson reported personal compensation from Teva, speaker/advisory board activities for Biogen, and research support from Biogen. Seven other authors reported being Biogen employees. Other authors reported no disclosures or various disclosures, including connections to Biogen.

SOURCE: Zhovtis R et al. ACTRIMS Forum 2018 Abstract LB250.

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