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Natalizumab to Anti-CD20 Switch – Washout Risks — SCE Neurology MCQ

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HardMultiple Sclerosis & CNS InflammationNatalizumab to Anti-CD20 Switch – Washout RisksSCE Neurology

A 30-year-old woman with MS on natalizumab for 4 years becomes JCV antibody positive with an index of 3.2. Her neurologist decides to switch to ocrelizumab. What washout period considerations are important when switching from natalizumab to anti-CD20 therapy?

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Correct answer: E — A short washout period (typically 6–8 weeks) is used to minimise the risk of disease rebound while allowing natalizumab to clear — but this period carries the highest risk of PML as natalizumab wears off and immune surveillance returns

Switching from natalizumab to another DMT is complex. The main risks are: (1) disease rebound during the washout period (severe relapses from rebound immune activation in the CNS — most dangerous 8–16 weeks after last natalizumab dose), and (2) carry-over PML risk (PML may emerge as natalizumab clears and immune surveillance is partially restored, unmasking subclinical JCV infection). A washout of 6–8 weeks is typical, with close MRI surveillance during the transition. Some centres use bridge therapy (short course of steroids or IVIg) during the washout. A: Some washout is needed for safety monitoring. C: 6 months is too long — rebound risk. D: Far too long. E: Overlapping is not recommended.

Reference: ABN MS Guidelines (2022); Plavina et al. Natalizumab Switch Guidance