8 thoughts on “Natalizumab – Safety Update December 2011”

  1. What does "Post Marketing" mean on the x-axis in the two graphs above ? Extrapolation from the second graph suggests that it is the PML rate prior to any infusions, but that seems nonsense given the numbers !

  2. Post-marketing means since the drug has been available on prescription.i.e. after the clinical trails used for the licencing of the drug.

  3. Please note that if you have been on Natalizumab longer than 24 months, have previously been treated with immunosuppressive drugs, for example mitoxantrone, and you are JC virus positive (blood tests shows you have antibodies to the virus) your risk of getting PML is 1 in 95. On the other extreme if you are JC virus negative your risk is less than 1 in 10,000.

  4. Re: "Does methylprednisolone use also place JC positive people in the 1/95 group after 24 months?"No this data excludes methylprednisolone and interferon beta and glatiramer acetate.

  5. Can a patient request a blood test if they have not been treated with immunosuppressive drugs? I am on my 31st tysabri infusion.

  6. According to Prof G you should ask your Neuro to do the test.All people on tysabri in our clinic have had the test, so I am told.

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