Tysabri and PML Risk

5/10/2014

Here is My Question:
My daughter has been on Tysabri for almost 4 1/2 years. At the end of year 2 she was put on "holiday" and after 3 months had what seemed to be a relapse but was in fact declared IRIS. She received steroids and was immediately put back on Tysabri. At the time, she was told that she could never come off Tysabri.

Fast forward 2 1/2 years. Her JC virus antibody values have tripled in the past nine months and are now at 1.3. This would suggest coming off Tysabri but what about the IRIS?

Answer:
The risk of PML on Tysabri is related to duration of therapy over two years, JCV antibody index and whether or not a patient has received prior immunosupression. For my response I will assume your daughter has not been treated with an immunosuppressant in the past.

According to our current understanding of these risk factors (CLICK HERE to read my previous blog on Tysabri risk), your daughter’s current risk of PML is approximately 1 in 1,000 or 0.1%. This number is taken from the figure below showing the risk of PML after 2 years of Tysabri therapy according to various JCV index levels. We have no information at present to suggest that the manner in which JCV antibody index values vary over time affects the risk of PML. The risk stratification is based on current index value and current duration of therapy. I hope this helps with your decisions.

-Rip Kinkel, MD

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4 Comments

laura charron

5/10/2014 12:43:33 am

What about the inevitable return of IRIS?

Laurie

5/10/2014 01:30:47 am

What is IRIS ?

Revere P Kinkel

5/11/2014 01:45:15 am

IRIS is an acronym for Immune Reconstitution Inflammatory Syndrome. This existence of this syndrome following discontinuation of Tysabri is somewhat controversial as many authorities believe this is just a bad relapse; nevertheless, the outcome is still the same. Think of IRIS in the following manner; while a patient is on Tysabri the immune response against the brain of MS patients is prevented from entering the nervous system. When you stop Tysabri, if this immune response is still active and the brain is receptive, inflammation can return to the nervous system in a manner analogous to a dam breaking and flooding the valley below. This usually occurs 4 to 6 months after stopping tysabri, when the effects have washed out. This response is not inevitable (less than 10% of patients experience this response) but if it has occurred in the past in an individual patient it is more likely to reoccur when Tysabri is discontinued again.

5/11/2014 07:20:46 am

If a patient develops IRIS after stopping Tysabri, do you recommend the patient resume indefinitely the use of Tysabri even if the JC Virus antibody counts increase to an unsafe level?

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