Questions about JCV and PML

Here is My Question:
Another JCV/PML question.

I'm a 50 year old mail, diagnosed RRMS about 10 years ago. Seems non aggressive, though symptoms have slowly built. 7t results indicates more gray matter activity than white matter.

​1.5 years on Avonex.
The last 6 years on Tysabri.
Just tested JCV positive, 2.6 on the index.

Two main questions. Not having more specific info, I understand that the responses have to be somewhat to the generic cases.

1. Treatment. Do I stop tysabri immediately? Move to extended time between infusions? What are the treatment options to to transition to.
2. Risk level for PML. With a relatively high JCV index (2.6) and 75-80 tysabtri infusions, I appear to be at "high" risk for PML. I don't really understand what is meant by high risk. An online calculator assessed my risk at 1/100.  If that is a reasonable guesstimate, what does it mean? Is there a time frame attached?

I've read that after 6 months off of Tysabri, the risk goes away. Is that a correct interpretation (from what is known)?

Is there anything that I can do other than waiting to see if symptoms of PML develop?

Are there diagnostic tests to see if PML development is starting?

If so, and development is seen, I have not seen any treatments that could be started. Is that the case?

THANKS!

Answer:
There is a lot to answer here, and you are correct that this answer will be more on the conservative side.  To get to the heart of your question, you should take these questions to your treating neurologist.

You appear to be in the higher risk group for PML.  High risk is relative and dependent on your natural affinity or avoidance to risk.  Lengthening time between infusions is reasonable to help mitigate some of the risk of PML, but there is still risk.  

Cortical demyelination seen on research magnets (7T) is highly associated with disability (whether in the present and future) but this metric hasn't been utilized in previous clinical trials and is difficult to comment on at this time.  What may be more significant is the slowly evolving symptoms you mention.  If by symptoms you mean more pervasive decline in function, that may indicate a secondary progressive course.  If present, moving away from Tysabri may be a consideration.

Coming off Tysabri can be problematic with rebound disease activity in approximately 50% of cases if nothing more is done.  A good consideration for a transition medication is rituximab or Ocrevus.

PML has been seen out to 6 months since stopping Tysabri, however that risk is small considered to the risk of rebound. 

Treatment of PML is supportive and focused on strategies to assist the immune system (typically in a hospital setting) to try and clear the virus.  If survived, PML leaves significant disability.

A. Scott Nielsen MD MMSc
Neurologist and MS Specialist at Kaiser Permanente

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