WSNS NEWS

Tysabri (natalizumab): New Risk Factor for PML
(January 23, 2012)
ISSUE: FDA notified healthcare profesisonals that testing positive for anti-JC virus (JCV) antibodies has been identified as a risk factor for progressive multifocal leukoencephalopathy (PML). PML is a rare but serious brain infection associated with use of Tysabri (natalizumab) for the treatment of multiple sclerosis (MS) or Crohn's disease.

A patient's anti-JCV antibody status may be determined using an anti-JCV antibody detection test that has been analytically and clinically validated, and has been ordered by a healthcare professional. The Stratify JCV Antibody ELISA test2 was cleared by FDA on January 20, 2012. Testing positive for anti-JCV antibodies means that a person has been exposed to JCV in the past.

RECOMMENDATION: The risks and benefits of continuing treatment with Tysabri should be carefully considered in patients who are found to be anti-JCV antibody positive and have one or more of the other known risk factors for PML. Patients with all three known risk factors* have an estimated risk of PML of 11/1,000 users See the Drug Safety Communication Data Summary section for additional information.
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Editor's note: The three risk factors are: 1) greater than two years on therapy, 2) prior use of immunosuppressant therapy, and 3) JC virus antibody positivity. See here regarding test availability.

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The purpose of this Society shall be:
- To promote the science and practice of neurology in Washington State;
- To advocate for neurologists and patients with neurologic disorders;
- To promote and protect the neurologic health of the public.