Tsyabri Efficacy Rate

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

Tsyabri Efficacy Rate

Postby daydreamer11 » Wed Dec 26, 2012 3:02 pm

Does anyone know the efficacy rate of Tysabri? I tried to find it on pubmed, but I don't really know where to look in the endless reports.
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Re: Tsyabri Efficacy Rate

Postby HarryZ » Thu Dec 27, 2012 7:01 pm

daydreamer11 wrote:Does anyone know the efficacy rate of Tysabri? I tried to find it on pubmed, but I don't really know where to look in the endless reports.


Read info on this link and see if you can make any sense of the numbers

http://www.uptodate.com/contents/natali ... -in-adults

Initially, Biogen, the makers of Tysabri, told us that MS patients had a 67% reduced risk of relapse over placebo users in the trials. They also said that the number of brain lesions was reduced significantly although lesions are known to come and go without medications and they do not correlate with MS symptoms.

While many patients do well on Tysabri, several do not. Because the drug is a very powerful immune system altering medication, patients can end up with other infections, especially PML which can be fatal.

Reports from patients who have stopped using the drug state severe relapses can take place.

Tysabri is one powerful drug so become as informed as possible before making any decisions to use it or not.

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Re: Tsyabri Efficacy Rate

Postby daydreamer11 » Thu Dec 27, 2012 7:16 pm

Thanks Harry. This really helps.
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Re: Tsyabri Efficacy Rate

Postby CureOrBust » Thu Dec 27, 2012 10:20 pm

HarryZ wrote:They also said that the number of brain lesions was reduced significantly although lesions are known to come and go without medications and they do not correlate with MS symptoms.
Harry, not speaking to Tysabri explicitly, I have heard this statement many times (probably yourself)_ I am a bit lazy, but have they found that generally speaking, playing the "odds", the greater the number of lesions, the greater the disability? Or is it completely random when plotted on a graph? Is it at all common for people to increase in lesion load while reducing in disability? or vice versa?
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Re: Tsyabri Efficacy Rate

Postby daydreamer11 » Fri Dec 28, 2012 5:46 am

I'm not really sure how they truly come up with an efficacy rate for any drug, when it is true that lesions and symptoms can come and go on their own.
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Re: Tsyabri Efficacy Rate

Postby CureOrBust » Fri Dec 28, 2012 6:34 am

even if lesions and symptoms may come and go on the individual, I think they would rely on the statistical outcomes.
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Re: Tsyabri Efficacy Rate

Postby HarryZ » Fri Dec 28, 2012 6:49 am

CureOrBust wrote:
HarryZ wrote:They also said that the number of brain lesions was reduced significantly although lesions are known to come and go without medications and they do not correlate with MS symptoms.
Harry, not speaking to Tysabri explicitly, I have heard this statement many times (probably yourself)_ I am a bit lazy, but have they found that generally speaking, playing the "odds", the greater the number of lesions, the greater the disability? Or is it completely random when plotted on a graph? Is it at all common for people to increase in lesion load while reducing in disability? or vice versa?


Cure,

The greater number of lesions "does not" equal greater disability. The critical factor is location of the lesions. One can have several lesions and few symptoms or just a few lesions and severe symptoms.

The drug companies, in their trials, often use the reduction in number of lesions vs placebo to "prove" efficacy of their drug. But other than looking nice on the charts, it isn't a true indication of what is happening.

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Re: Tsyabri Efficacy Rate

Postby HarryZ » Fri Dec 28, 2012 7:01 am

CureOrBust wrote:even if lesions and symptoms may come and go on the individual, I think they would rely on the statistical outcomes.


Statisical outcomes in trials can be manipulated to "prove" a point. That's how Copaxone eventually got approved after first being rejected by the FDA for statistical insignificance. In reference to your previous question on lesions, the companies always show that there are fewer lesions for those who take the drug vs those who don't. But while being a nice stat, it doesn't translate into the drug having a good efficacy.

We often hear that certain drugs reduce the number of exacerbations by about 33% over placebo. So if a patient had 2 attacks a year, they now have 1.3 attacks! Is that really helpful in view of the side effects and cost of the medication? I guess it depends on how one looks at it.

In the case of Tysabri, Biogen told us that the reduction in risk of attack was 67% over placebo, whatever "reduction in risk" means.

The companies who conduct these trials spend a ton of money on them and they need to ensure statistical significance to get approval. The temptation to manipulate can be very high when the reward in drug sales is so high.

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