PML Update: May 2013

“Biogen-Idec the company that helped develop and market natalizumab are concerned that my monthly PML update is too complicated for MSers to understand. I have therefore tried to simplify the slide deck. This is a work in progress and will need to be improved on when I have some spare time. Any feedback on its contents would therefore be very helpful. For one it is too long.”

As of 6th May 2013 there have been 359 confirmed cases of natalizumab-associated PML.

“I am aware that a lot of my professional colleagues have begun to use this blog as an easy way to access the latest PML data. I will therefore make the ‘for professionals only’ slide deck from Biogen-Idec available as well on a monthly basis for healthcare professionals via the blog.”

“Apologies about being so patronising.”

CoI: multiple

About the author

Prof G

Professor of Neurology, Barts & The London. MS & Preventive Neurology thinker, blogger, runner, vegetable gardener, husband, father, cook and wine & food lover.


  • SLIDE 13 gets the risk across,maybe this is what we need to see and the risks of what happens if you get PML, the rest makes me abit dotty

  • Biogen-Idec is concerned on behalf of MSers about the contents of YOUR blog???

    Why don't you ask your readers directly as you do with everything else? Why should Biogen-Idec be entitled to any opinion about what you write? It's none of their business, as far as you stick to their numbers. This is insulting, i wonder why you let it happen.

    • Everybody is entitled to an opinion, so is Biogen! Why should their opinion be considered more insulting than that of anybody else

    • Shouldn't Biogen have an interest in how their data is presented?
      Seems reasonable to me. There's no suggestion they're trying to hide anything here.

    • Reasonable, hmm. A multi-billion drug company gets in the shoes of an MSer and decides that some posts in a clinicians blog are a bit blurry to perceive.

      Well, why don't THEY present them the way they like and go with a press release?

      Maybe because this blog is very popular among MSers and Prof GG has gone into great detail in describing what PML really is…

  • Slides 14 & 15 may have a problem. People who have not received previous immuno-suppression cannot have a higher chance of PML

    Slide 14 says: JCV+ MSers WITH previous immuno-suppression have a 1 in 552 chance of PML

    Slide 15 says: JCV+ MSers WITHOUT previous immuno-suppression have a 1 in 192 chance of PML

    • The slides are correct, it reflects the time being treated with natiluzumab and JCV positive status with or without previous immunosuppression ie the risk of PML if you are JCV positive is increased with the duration of natiluzumab treatment whereas with/without previous immunosuppression seems to make less of a difference.

  • Thank you for this (Biogen patronising suggestions aside).

    Is there any information regarding the limitations of possible cancer therapy treatment if a person develops cancer while on Tysabri?

    And also regarding likelihood of greater increased disease activity after discontinuing Tysabri than that prior to starting on it (with or without PML occurrence)? (I thought there was some data on this after the clinical trials but with PML dominating attention, I have not recently seen any updates on these aspects.)

    • Biogen-Idec are not allowed to communicate with MSers directly in most countries; the US being the exception. Hence for 'healthcare professionals only'; I have to respect their position as they have a responsibility to obey the law. I personally think the law needs to catch up with the information age; why should the distribution of information be restricted to healthcare professionals' eyes only? Surely MSers need access to this information? Can we assume all MSers are incapable of digesting medical information. I look after several doctors with MS; why should they have selective access to this information.

      I am determined to continue distributing information on this issue and others to MSers.

  • Because the reaading is not great. You have a drug that has some great effects and you have a drug that has important side effects… up to a 1 in 100 chance of a disease that will kill you in 1 in 5 cases. To pretend otherwise is not sensible, but this is about managing information.

    Biogen do not like the way that Prof G relays it..because they have funded a marketing department to feed you what you want. Do not buy it. Do the home work and question

    • I think Biogen may have a point. We need to keep the message simple. I will post tomorrow on this exact issue.

  • ive tested jc virus positive have been on tysabri for 6yrs what are my true risks have meeting weds with consultant who wont tell the thruth im sure,

  • 372/85 and still no escape plan following Tysabri discontinuation. Well done everybody.

By Prof G



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