Tysabri PML Risk-Minimization Strategies Working, Study Finds

Cases of serious brain infections linked to the multiple sclerosis (MS) drug Tysabri are decreasing for the first time since the drug was released, according to the findings of a new study.

Tysabri side effects are known to include a risk of progressive multifocal leukeoencephalopathy (PML), a potentially lethal brain infection. However, in findings published this month in the medical journal JAMA Neurology, researchers indicate that recent risk-minimization strategies appear to be decreasing rates of this rare infection for the first time.

PML is a rare and deadly brain infection linked to several different immunosuppressant drugs, including Tysabri (natalizumab). It and similar drugs suppresses the immune system allowing the JC virus, which causes PML, to proliferate.

Tysabri, which is manufactured by Biogen Idec Inc. and marketed by Elan Corp PLC, has been shown to prevent MS relapse, cognitive decline, and vision loss in patients. For patients who don’t experience PML, it greatly improves their quality of life.

Past research indicated careful monitoring of MS patient’s taking Tysabri could help reduce the incidence of the PML brain infection. Researchers found that using monitoring techniques like MRI and other forms of diagnosis can help detect the early signs of PML, leading to better outcomes.

French researchers conducted a multi-center study on 6,300 patients with multiple sclerosis who enrolled in the French multiple sclerosis registry from 2007 to 2016. Patients were treated at MS expert centers and MS-dedicated networks of neurologists in France.

According to the findings, incidents of PML decreased by 23% each year since January 2013, when risk minimization guidelines were first implemented.

Before the guidelines, there was a 45% annual increase in PML cases seen among MS patients taking Tysabri. However, from 2013 to 2016, the rates of PML decreased by 23% each year using minimization methods, such as MRI monitoring.

Researchers emphasize the need to continue the current risk evaluation and mitigation strategy focused on careful monitoring, including necessary imaging and followups to help patients with MS maintain quality of life while avoiding the serious risk of PML.

“This finding appears to support the continuation and reinforcement of educational activities and risk-minimization strategies in the management of disease-modifying therapies for multiple sclerosis,” the researchers concluded.