Should I wait to see if PML develops or should I start Rituximab?

Question:
My question is how relevant are 11 copies/mL of JCV DNA in my LP CSF? Dec '15 I stopped Tysabri after 30 infusions with a view to start Lemtrada. Whilst on Tysabri I have always tested JC negative with a titer of 0.18 Now after a further LP test with the same result and a course of G-CSF my neurologist is saying it might be too risky to start an induction treatment. Rituximab has been suggested as an alternative. Over the last couple of months I am sure I have had a relapse and in any case my walking/balance has deteriorated, however this may have been due to a particularly bad infection of my right axilla which has been treated by 2 weeks of oral high dose antibiotics. Should I wait longer to if PML develops or should I start on Rituximab?

Answer:
We and others have observed transiently positive JCV PCR studies on CSF samples from Tysabri treated MS patients with no evidence of PML. In the absence of symptoms or MRI findings over a 6 month period this is not likely significant. However, the results should be become negative on repeat CSF testing and your JCV antibody testing should remain negative. Depending on where the testing was done this could also be a false positive test. Have your neurologist contact the Biogen Medical Science Liason to obtain more specific testing from one of the research labs.

Revere (Rip) Kinkel MD
Director of the Multiple Sclerosis Program
Professor of Clinical Neurosciences
University of California San Diego