...the Neuro (...) informed us that between 4-6 months out from discontinuing Tysabri there is a risk of IRIS or Immune Reconstitution Inflammatory Syndrome. This wasn't mentioned in relation to PML, but to anyone stopping Tysabri after being on it for a long period of time.
So, not only is there PML to consider with Tysabri, but also IRIS once a patient comes off Tysabri which seems inevitable at some point considering the unknowns around long-term Tysabri use.
I have always thaught that IRIS has been connected with PLEX (plasma exchange), only...
1) FDA warning (February 2010): http://www.fda.gov/Safety/MedWatch/Safe ... 199965.htm
2) Professor David Bates article (US Neurology):
"During recovery from PML, immune reconstitution recovery syndrome
(IRIS) is an expected condition. This appears universal in PML
associated with natalizumab, unlike PML in AIDS, regardless of whether
natalizumab is removed rapidly or simply discontinued. IRIS generally
occurred four weeks after stopping natalizumab treatment, but in some
cases it occurred earlier. Corticosteroids, sometimes multiple courses,
given early in the course of IRIS appeared to lead to improvement in
most patients. To date, most of the natalizumab-treated patients who
developed PML have survived, but exhibit varying levels of disability."
3) The Lancet Neurology (April 2010): Clifford DB, DeLuca A, Simpson DM, Arendt G, Giovannoni G, Nath A. (Department of Neurology, Washington University in St Louis, Saint Louis)
"Management of PML has routinely used plasma exchange (PLEX)... Exacerbation of symptoms and enlargement of lesions on MRI have occurred within a few days to a few weeks after PLEX, indicative of immune reconstitution inflammatory syndrome (IRIS). This syndrome seems to be more common and more severe in patients with natalizumab-associated PML than it is in patients with HIV-associated PML."