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Natalizumab PML Risk – JCV Index 2.8 — SCE Neurology MCQ

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ModerateMultiple Sclerosis & CNS InflammationNatalizumab PML Risk – JCV Index 2.8SCE Neurology

A 55-year-old man with MS has been on natalizumab for 3 years. He is JCV antibody positive with an index of 2.8. He has no prior immunosuppressant use. What is his approximate PML risk, and what should be discussed?

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Correct answer: A — High risk — with JCV index >1.5 and >2 years of natalizumab treatment, the PML risk is approximately 1 in 100 per year (1%); the risk-benefit of continuing vs switching should be urgently discussed

PML risk stratification on natalizumab uses three factors: (1) JCV antibody status and index, (2) duration of natalizumab treatment, (3) prior immunosuppressant use. With JCV index >1.5, >2 years of treatment, and no prior immunosuppression, the risk is approximately 1 in 100 per year (1:100). With prior immunosuppression, risk is even higher (~1:80). This represents a clinically significant risk and switching to an alternative DMT should be strongly considered. The discussion must involve shared decision-making with the patient. A: Risk is significant at this level. C: Higher than 1:10,000. D: JCV is the key risk factor. E: Discussion of switching is appropriate.

Reference: ABN MS Guidelines (2022); Bloomgren et al. PML Risk Stratification