Here is My Question:
Does the level you are JC + at increase risk of PML? I am at a 3.19. My medication options are Copaxone or Tecfidera. Would it still be safe for me to take Tecfidera or too risky? Thank you.
The JC virus antibody index level can be helpful in estimating risk for PML for patients on Tysabri. Retrospective data analysis suggest the higher the index level, the greater the risk for PML when exposed to Tysabri (as well as ~6 months after tysabri discontinuation). We do not have the same breadth of data for the association of JC virus antibody status and index level with tecfidera. While it makes sense that a positive test with higher index level would confer a higher PML risk on tecfidera (since there are reported cases of tecfidera associated PML cases), there simply isn’t enough data to use the lab test the same way we use it for tysabri. Another reason it may not be a good idea to establish an equivalence in lab interpretation between these two drugs is that their mechanism of action differ significantly which may influence the risk for PML based on that fact alone.
With several therapy options (both FDA approved and off label use), you may have more options than the two you listed. I’d suggest reviewing these with your prescribing physician.
A. Scott Nielsen MD MMSc
Neurologist and MS Specialist at Kaiser Permanente
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