A best treatment pathway has been identified for people with multiple sclerosis (MS) whose current medication puts them at risk of a serious brain infection.

MS patients who take the highly effective drug natalizumab are monitored regularly for their risk of developing a potentially deadly brain infection known as progressive multifocal leukoencephalopathy (PML), caused by a human virus called John Cunningham virus (JCV).

Even though the risk of PML is small, the prognosis is poor, with an average six-month life expectancy.

If their six-monthly blood monitoring shows an increased risk of JCV, many patients switch treatment, but patients who stop taking natalizumab can be at risk of severe MS relapses. Until now, understanding which alternative drug would be best was not known.

However, a study published in JAMA Neurology has identified which of the drugs among dimethyl fumarate, fingolimod and ocrelizumab is most effective after stopping natalizumab.

Researchers analyzed real world data collected from the international MSBase registry tracking outcomes in over 89,000 patients with multiple sclerosis.

The study identified 1,386 patients worldwide who had changed from natalizumab to dimethyl fumarate, fingolimod and ocrelizumab.

Ocrelizumab was the most effective in patients who had stopped taking natalizumab. Relapse risk and discontinuation rates were lower for ocrelizumab than dimethyl fumarate and fingolimod.

First author Dr. Chao Zhu, of the Monash University Central Clinical School's Department of Neuroscience, said the findings were important globally for clinicians and patients. He said they could help inform treatment decision making and maximize an optimal strategy for patients who need to stop natalizumab.

"Some countries have limited treatment options available due to the high costs to produce some of the newer, more effective drugs, or have strict guidelines on what can be used as first-line treatment, or some cannot be used if women intend on childbearing," Dr. Zhu said.

Senior author Professor Helmut Butzkueven, of the Monash University Central Clinical School Department of Neuroscience, and The Alfred's Department of Neurology, said it was important for clinicians to monitor MS patients for their risk of JCV using a blood test.

"If patients need to change their medication from natalizumab, which is highly effective in treating MS, it can be an anxious and distressing time. Our study helps neurologists and patients make a better-informed choice."