After years on Tysabri, my JCV was higher than was considered safe so I switched to another med. Does that JCV level go down over time? Does is stay at that high(er) level?
There is no evidence at present that the amount of JCV antibodies (i.e. the JCV antibody index value) when you are tested is related to being on or off treatment with Tysabri. JCV antibody index values will fluctuate over time and can either go up or drop to undetectable levels ( i.e a Negative JCV antibody result in a person previously positive). Generally, index values tend to stay within a certain range, either negative or low (< 1.5) or high (> 1.5) with repeat testing; but this is not always the case and requires continuous monitoring while on treatment.
The important thing to remember is that we have no knowledge of a person developing PML more than 6 months after stopping Tysabri, regardless of JCV antibody index values or treatments used after stopping Tysabri.
Rip Kinkel, MD