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Is Tysabri dosage the same for everyone? Or is it based on patient weight?

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    Is Tysabri dosage the same for everyone? Or is it based on patient weight?

    I think I read somewhere that the amount of Tysabri given during a single infusion is the same for everyone regardless of size - is that true?

    I remember it was suggested that of patients that meet the stated PML risk factors (JCV+, been on the drug >2 years, etc) - that it was typically smaller individuals that would get PML. I don't know if this is accurate either, but if the drug dose was the same for everyone it might follow that a smaller individual would have a proportionally higher concentration of the drug in their system.

    Anyway my reason for asking is that I've been encouraged to see the posts and studies that have shown a significant decrease in PML risk without much loss of efficacy for patients on an extended (8 week) dosage schedule. I was wondering if it is known (or is planned to study) whether a smaller dosage given on the 4-week schedule would similarly decrease risk? It seems like it would be potentially less taxing on a patient's system to have a smaller dose at more frequent intervals. (This is just my own logic and thought stream, no foundation in medicine at all).
    Sx since 2007; Dx Oct. 2014. Started Copaxone after Dx...praying that it's working!

    #2
    [QUOTE=malaholic;1508399]I think I read somewhere that the amount of Tysabri given during a single infusion is the same for everyone regardless of size - is that true?

    True.

    I remember it was suggested that of patients that meet the stated PML risk factors (JCV+, been on the drug >2 years, etc) - that it was typically smaller individuals that would get PML. I don't know if this is accurate either,


    Low weight patients get PML more frequently. Google "Low weight may contribute to risk for natalizumab-induced PML"

    but if the drug dose was the same for everyone it might follow that a smaller individual would have a proportionally higher concentration of the drug in their system.

    You hit the nail on the head. The higher concentration of immune suppressant (Tysabri) allows less immune surveillance against the JCV, therefore, more cases of PML.

    Anyway my reason for asking is that I've been encouraged to see the posts and studies that have shown a significant decrease in PML risk without much loss of efficacy for patients on an extended (8 week) dosage schedule.

    You are correct, again. Google, "Less Frequent Natalizumab dosing Dramatically Reduces PML risk"

    I was wondering if it is known (or is planned to study) whether a smaller dosage given on the 4-week schedule would similarly decrease risk? It seems like it would be potentially less taxing on a patient's system to have a smaller dose at more frequent intervals.

    There is no planned study I have heard of involving less than the standard 300mg.

    JMHO, but waiting to get worse before getting on Tysabri is extremely unwise. The goal is to stop progression. I believe Copaxone had zero effect on halting MS progression in trials.

    93% on Tysabri experienced no EDSS progression in a study of 343 patients between 2007 and 2010 as evidenced below...

    Natalizumab treatment in multiple sclerosis patients: a multicenter experience in clinical practice in Italy. Int J Immunopathol Pharmacol. 2014 Jul-Sep;27(2):147-54.

    "We evaluated efficacy of natalizumab in relapsing-remitting multiple sclerosis patients in a clinical practice setting. We report data on the first consecutive 343 patients receiving natalizumab in 12 multiple sclerosis (MS) Italian centres enrolled between April 2007 and November 2010. The main efficacy endpoints were the proportion of patients free from relapses, disease progression, combined clinical activity, defined as presence of relapse or disease progression, from MRI activity, and from any disease activity defined as the absence of any single or combined activity. At the end of follow-up, the cumulative proportion of patients free from relapses was 68%; the proportion of patients free from Expanded Disability Status Scale (EDSS) progression was 93%; the proportion of patients free from combined clinical activity was 65%; the proportion of patients free from MRI activity was 77%; and the proportion of patients free from any disease activity was 53%. Natalizumab was effective in reducing clinical and neuroradiological disease activity. Its effectiveness in clinical practice is higher than that reported in pivotal trials and was maintained over time."

    Comment


      #3
      Myoak, thank you so much for your thoughtful reply. As I go about the business of reading different articles/studies/etc and trying to assimilate information across various sources, it is very helpful to hear from you because you've already done so!

      Originally posted by Myoak View Post
      JMHO, but waiting to get worse before getting on Tysabri is extremely unwise. The goal is to stop progression. I believe Copaxone had zero effect on halting MS progression in trials.
      With the promising news about extended dosing reducing PML risk I am starting to lean that way, which is why I am now trying to study up. I've been hesitant to date about moving to a "big gun" drug for several reasons:
      • PML - currently I'm doing pretty well; I'd rank maybe only 1.5 on EDSS and have seemed fairly stable since the attack that got me Dx'ed ~4 years ago. Even a smallish risk for PML seems huge when you have a lot to lose.
      • Increased susceptibility to infections - I already seem to catch every single cold/bug that goes around, and when I do they last FOREVER. I haven't wanted to make that even worse.
      • So far Copaxone has seemed to "work" - annual MRIs have been stable (so far) and while lingering symptoms vary based on things like sleep/stress/etc, I can't say I've had a major relapse (knocking on wood here).
      • If something were to happen that would require me to stop Tysabri (JCV titer too high, allergic reaction, etc). then I worry about having a rebound relapse and how bad that could be.


      However, I'm starting to come around and look at things from a different perspective which is probably closer to your own. I'm thinking about how, unlike before, I did *not* recover 100% from that last attack. I may have exceeded my capacity for repair. If so, then I should expect that the next attack - whenever it comes - will leave me with even more lasting damage. Just as you stated, waiting until I get worse is already too late.

      So now I am more open to a switch, but just trying to educate myself about alternative dosage/schedule options that could reduce the PML risk for my small self. My next round of MRIs and neuro visits is in a couple of months, so I'm trying to be as informed as possible before I talk with her about it.

      Many thanks for your reply and the additional information you pointed me to!
      Sx since 2007; Dx Oct. 2014. Started Copaxone after Dx...praying that it's working!

      Comment


        #4
        Malaholic,

        You are so welcome. Your personal research is laying the groundwork for the best decision possible. Yes, I am a big fan of tysabri because for a huge chunk of those taking it, it is as close as they can come to living as though they don't even have MS. There are risks with every med. There is risk in what we do but there is risk in what we don't do, also. The aspect of risk not many realistically consider is the risk of NOT doing something, especially the risk of not aggressively halting MS progression and suffering worse MS.

        A couple of thoughts... if you do not have children yet and want to someday, please discuss that with your neuro as a part any treatment plan. Possibly, he would not want you on a particular med if that is the case. Accidental pregnancies on Tysabri have generally been similar to the regular population (please google "Evaluation of pregnancy outcomes from the Tysabri pregnancy exposure registry"), however, it is not recommended. Be sure to discuss it with your neuro but read that study, also, because he likely didn't have time and doesn't know what is in it. Also, on a personal note... if you don't ever plan to have children you will regret it more than you can possibly imagine when you are older, IMO. Sometimes, families have to be planned, you know, or they don't happen!

        Also, don't expect you will have any more infections on Tysabri than you have now. my guess is that you will have less based on people on Tysabri I have observed for 15 years. My wife has not averaged anywhere near one cold per year on Tysabri. Some people apparently do sometimes, I just have not seen them at home or at the infusion center.

        I congratulate you on investigating your treatment decisions! I probably already mentioned it but google "barts ms blog" for a really great research site.

        Best to you!

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