Tysabri Efficacy

A board to discuss the newly-released drug Tysabri, (formerly known as Antegren) as a treatment for Multiple Sclerosis

Tysabri Efficacy

Postby MetsFan » Tue Jan 10, 2006 7:04 pm

Whether you believe Tysabri should come back or not, it is useful to understand the drug's efficacy. Elan did a presentation to an investor conference today, and there are some fascinating slides which illustrate the drug's effectiveness. The information is from the AFFIRM two year trial which compared Tysabri to placebo:

RELAPSES:
66% reduction in relapse rate in Year 1
67% reduction in relapse rate over Two Years
http://www.tixx.com/jpm2006/target14.html


NEW or NEWLY ENLARGING T2 LESIONS:
80% reduction in Year 1
83% reduction over Two Years
http://www.tixx.com/jpm2006/target15.html


NUMBER OF GADOLINIUM ENHANCING LESIONS:
93% less in Year 1
93% less over Two Years
http://www.tixx.com/jpm2006/target16.html


RISK OF DISABILITY PROGRESSION:
42 % reduction over two years
http://www.tixx.com/jpm2006/target17.html


All of the above information has been presented at medical conferences in the last year, but not in such a user-friendly format.

It is important to note that 6% of Tysabri patients will develop persistent neutralizing antibodies. For this group, the drug does not work at all - zip, zero, nada. If the companies were to quote the above numbers ONLY for the 94% who do not develop antibodies, they would be higher.

I wonder when the companies will release the % of people whose EDSS actually IMPROVED while on Tysabri. That is a most interesting number to know.
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Re: Tysabri Efficacy

Postby HarryZ » Tue Jan 10, 2006 9:21 pm

Metsfan,

Those numbers on Tysabri have been around for some time now. It's not surprising that Elan would be again promoting them just prior to the anticipated re-approval of the drug by the FDA. We can expect more of this marketing and sales efforts by both Elan and Biogen...this is how drug companies operate.

As one very knowledgeable poster on the Brain Talk MS Forum wrote (he has MS as well) you have to be careful on how you interpret numbers. He did an in depth analysis of the the Affirm trial and ended up comparing the stats against the CRAB drugs. He ended up stating that Tysabri showed a 12% efficacy increase over the CRABs. He also went on to say that the Affirm trial patients were not at the same level of MS illness that other trials were and that the chances of infection with Tysabri were greater because of the very nature of how the drug works.

You also mentioned that if the 6% of the neutralizing antibody patients who received no benefit from Tysabri were not included in the numbers, the results would be higher. Unfortunately it doesn't work that way in trial data....everybody has to be included in order to obtain statistical accuracy. You just can't pick and choose!

As for the % of people whose EDSS actually improved on Tysabri...I don't believe that those numbers have ever been made public by Elan which leads me to believe that they may have not been too favorable. I do know that I asked my wife's neurologist who had patients that participated in the Affirm trial, this very same question. He told me that there was no improvement in the EDSS for his patients and that Tysabri would likely be used for initial, minor levels of MS. He also went on to say that Tysabri patients would have to be carefully chosen because of the possible infection danger.

Tysabri will be back...the FDA will re-approve it but likely under several conditions including the "black box" label. How it will do outside the environment of the clinical trial atmosphere will only be known after several months of use.

Harry
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Postby MetsFan » Wed Jan 11, 2006 9:02 pm

<As for the % of people whose EDSS actually improved on Tysabri...I don't believe that those numbers have ever been made public by Elan which leads me to believe that they may have not been too favorable.>

Stabilization of EDSS was an endpoint of the AFFIRM study. It is captured in the 42% reduction in EDSS progression number.

Improvement in EDSS was NOT an endpoint in the study which must be determined prior to initiation of the study. Therefore, the companies cannot release this number. This would be considered "data mining" by the FDA.

Through the grapevine, I have heard a number and it is significant, but as it has not been publicly quoted, I won't repeat the number.
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Postby HarryZ » Wed Jan 11, 2006 10:02 pm

Metsfan,

Stabilization of EDSS was an endpoint of the AFFIRM study. It is captured in the 42% reduction in EDSS progression number.


A few people that I have spoken to about this didn't quite understand what Biogen/Elan were trying to say when they quoted "risk of disability reduction" in the trial info. You either stay the same, drop in EDSS score or get worse. Most patients in the Affirm trial had very low EDSS scores to begin with...if I can recall, they were all less than 2 and were not that sick with their MS. So it's not surprising that the "risk" of disability was favorable.

Improvement in EDSS was NOT an endpoint in the study which must be determined prior to initiation of the study. Therefore, the companies cannot release this number. This would be considered "data mining" by the FDA.


Absolutely correct.....if it isn't a planned endpoint in the trial, you can't use it in any official trial results. I'm kind of surprised that EDSS wasn't a major endpoint in the trial because it is the best overall measurement of how a MS patient is doing. Reduced lesions and exacerbations don't mean very much if your EDSS score gets higher as time passes on.

Through the grapevine, I have heard a number and it is significant, but as it has not been publicly quoted, I won't repeat the number.


I guess it depends what "grapevine" is involved. Like I said in the previous message, I asked my wife's neuro about the patients he had in the Affirm trial and he told me there was no EDSS improvement at all. That's why we really won't know how effective Tysabri is until it is out for several months and many patients start to use it outside of the trial setting.

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