When do you recommend I retest blood to make sure no upward trend in my JCV index?

Here is My Question:
I've been taking Tysabri for a year and a half and have always been JCV negative. Just got back results positive .45. When do you recommend I retest blood to make sure no upward trend? How fast can index potentially rise from .4 to .6? ....

Answer:
Great question. Since January 2012 when the JCV index became widely available to assess risk of PML on Tysabri, only 2 patients who were anti-JCV Ab negative at baseline (like yourself) out of total of 34,379 patients negative at baseline developed PML. This data can also be converted to a PML incidence rate of 0.058 per 1000 patients or 1 case of PML per 17,000 people treated in patients who were anti-JCV Ab negative at baseline (before starting Tysabri) . This is regardless of whether patients subsequently turned JCV index positive.

While this news is reassuring, it doesn't directly answer your question. Clearly, the risk of PML will go up in people who become JCV Index positivee and requires more frequent testing to assess this risk over time.  For people, like yourself, with low titer positive conversion (usually, this includes index levels between 0.4 and 0.9), we often recommend switching to every 6-week infusions and repeat JCV index testing every 3 months. There is randomized clinical trial data that 6-week infusions are as beneficial as 4-week infusions in people who go on extended interval dosing after a year of Tysabri monthly treatment; there is also data derived from the TOUCH registry that extended interval dosing reduces the risk of PML. Therefore, we also usually recommend switching to every 6-week infusions of Tysabri. 
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If your JCV index rises above 1.0 (many specialists have a different JCV index cut off levels for stopping Tysabri, but this is mine) with continued JCV index monitoring, we often recommend switching to another DMT, often an anti-CD20 therapy (i.e., Ocrevus, Briumvi, Rituximab or Kesimpta) after ensuring there is no evidence of pre-symptomatic PML by repeat MRI prior to starting the new therapy.
Hope this information helps with your discussions with your doctor and your ultimate decision. As usual the ultimate recommendation by your MD may depend on additional information we are not aware of such as your prior use of immunosuppressant therapies, age, disease type or co-morbidities.

Revere P (Rip) Kinkel, MDProfessor of Neurosciences
Director of the Multiple Sclerosis Program
University of California San Diego
#Tysabri #multiplesclerosis #JCVindex