Wednesday, 30 November 2011

Natalizumab PML Update - 181 cases as of 1st Nov


Status of MS'ers with PML as of 1st November, 2011
  • 38 patients have died (21%); most of the deaths have occurred within approximately 2 months after PML diagnosis 
  • 143 patients are alive (79%), it is too early to draw conclusions about the outcomes of patients who develop PML while on natalizumab treatment.

The following is the risk profiling algorithm with updated risks:


"It is clear that Natalizumab is associated with a risk of getting PML that varies depending on JC viral status, previous exposure to other immunosuppressive drugs and duration of treatment. Knowing these risks will allow you and your neurologist to make an informed decision on what to do with your treatment."


"In my opinion, a defined risk is better than an undefined risk."


CoI: Multiple, please note that all the data in this post has been supplied by Biogen-Idec as part of their "monthly natalizumab safety update and PML risk stratification programme".

6 comments:

  1. Hi Prof G, does nataluzimab treatment increase other oppportunistic infections in the brain, such at Toxoplasmosi (the parasite from cat poo) or Meningococcal disease? Or is there something special about JC virus?

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  2. Just last month, as a Tysabri user, I was given "the new blood test for Tysabri patients" and with it an informstion leaflet. The "false negative rate" is quoted as 2.5%, which seems quite high. Is this considered good / bad / normal ?

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  3. Re: ".. does nataluzimab treatment increase other oppportunistic infections in the brain, such at Toxoplasmosi (the parasite from cat poo) or Meningococcal disease? Or is there something special about JC virus?"

    I am not sure; these diseases are very rare in adults. What Natalizumab does is change the clinical presentation of CNS infections. Eg. herpes encephalitis looks different, more a slowly progressive presentation rather than an acute encephalitis.

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  4. Re: "The "false negative rate" is quoted as 2.5%, which seems quite high. Is this considered good / bad / normal ?"

    I agree; I suspect this is too conservative and is more likely to be lower than this. Most of the cases who develop PML have high titres and are not at the low positive end of the assay.

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  5. Are there any other pharma companies developing and testing JC virus assay tests or is it just Biogen?

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  6. Re: "Are there any other pharma companies developing and testing JC virus assay tests or is it just Biogen?"

    There other tests available. Biogen are claiming their assay is more specific and the only one that has been validated in MS. In the UK we use and assay that is provided by the Health Protection Agency (HPA); the equivalent of the CDC in the US.

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