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Natalizumab PML risk — SCE Neurology MCQ

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HardMSNatalizumab PML riskSCE Neurology

A woman with relapsing-remitting multiple sclerosis has received natalizumab for 30 months. She has not used an immunosuppressant previously, but her anti-JCV antibody index is 1.8. She remains clinically stable and her latest MRI is unchanged. Which surveillance strategy is most appropriate for progressive multifocal leukoencephalopathy risk?

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Correct answer: D — An abbreviated brain MRI every 3 to 6 months with continued clinical vigilance

PML risk rises with anti-JCV antibody positivity, treatment beyond 2 years and, independently, prior immunosuppressant exposure. In an anti-JCV-positive patient without prior immunosuppression, the index further stratifies risk; an index above 1.5 after more than 2 years is a high-risk pattern. The Tysabri SmPC advises considering more frequent MRI, for example every 3 to 6 months using an abbreviated protocol, in such higher-risk patients. Serum anti-JCV antibody testing supports risk stratification but does not diagnose PML, and routine CSF or serum JCV PCR is not a substitute for imaging and clinical vigilance.

Reference: TYSABRI 300 mg concentrate for solution for infusion SmPC: https://www.medicines.org.uk/emc/product/222/smpc