Re: What's the skinny on Tysabri?

The ironic part of the Tysabri affair is that some of the patients were
taking a drug to fight a demyelinating disease that affected some of the
oligodendrocytes in the brain (MS) ended up with a disease that affected
many more, massively destroying myelin (PML).

Dave

--

"Tim" <twesner@xxxxxxx> wrote in message
news:1122225187.459473.179730@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>I was asked to write a comparison of Tysabri and Tovaxin, here it is.
>
> Tysabri was approved last November for use with people suffering from
> MS. It reduces the number of attacks by 2/3 verses 1/3 with the current
> drugs. It reduces brain liaisons by 90% and reduces the progression of
> disability by 44%. It got fast tracked and was heralded as the next
> generation of MS treatments. It was the drug that Tovaxin would have
> gone head-to-head with in Phase III clinical trials.
>
> What is Tysabri? It is a Monoclonal Antibody
> http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Monoclonals.html
> -- an antibody that is mass-produced in the laboratory from a single
> clone and that recognizes only one antigen. Monoclonal antibodies are
> typically made by fusing a normally short-lived, antibody-producing B
> cell to a fast-growing cell. The resulting hybrid cell multiplies
> rapidly; creating a clone that produces large quantities of the
> antibody.
>
> MS is considered to be an autoimmune disease in which the person's
> immune system attacks the brain and/or spinal cord. Tysabri appears to
> work by binding to these immune system cells, thus preventing them from
> traveling to the brain where they can cause damage.
>
> Antibodies are proteins produced by a person's immune system to fight
> foreign substances, such as infections. Monoclonal antibodies, such as
> natalizumab (Tysabri), can be produced in large quantities in cell
> culture in a laboratory setting. They can be designed to bind to
> proteins on the body's normal cells. By recognizing and attaching to
> these proteins, monoclonal antibodies can interfere with (or alter)
> normal or abnormal cellular responses. In this way, monoclonal
> antibodies may be useful in the treatment of certain diseases such as
> MS.
>
> What killed the patient? The reports involved at least three cases of
> progressive multifocal leukoencephalopathy (PML)
> http://healthlink.mcw.edu/article/921450160.html , a rare but often
> fatal disease that affects the nervous system. In two of the cases, the
> patients had been taking Tysabri for more than two years in combination
> with another MS drug, Avonex. In the third case, the person was taking
> only Tysabri and was in a Crohn's Disease study.
>
> It is suspected that Tysabri or the combination of Tysabri and Avonex
> allowed this rare viral infection to take hold. 80% of all adults have
> been exposed to this virus, but it is rare for someone to be affected
> by it. Someone with a compromised immune system, such as AIDS, would be
> a candidate to get this. Possibly Tysabri or the combination of the two
> drugs altered the patients immune system enough to allow the virus to
> attack.
>
> PML is a demyelinating disease and it was first thought that these
> patients were having an MS attack. There is no known cure for PML and
> diagnosis is usually done by autopsy. It may be possible to diagnose it
> with a spinal tap, but currently, an MRI assessment is used when PML is
> suspected.
>
> What does Tysabri's withdrawal mean to the approval of Tovaxin, and
> whether or not Tovaxin will get fast tracked? Tysabri has no bearing on
> whether or not Tovaxin gets approved. Tysabri is a monoclonal antibody
> and Tovaxin is an autologous T-cell elimination. Tysabri is a
> laboratory created antibody that attaches itself to T-cells thus
> preventing them from crossing the blood-brain barrier. It stops almost
> all T-cell from crossing, not just the bad ones.
>
> Tovaxin http://www.pharmafrontierscorp.com/toxavin.php is a vaccine,
> which uses the patient's own blood. Like a flu shot, it makes the body
> form antibodies against a select T-cell, which attacks myelin. It does
> not interfere with any other T-cells and has no effect on the
> blood-brain barrier. There is virtually no health risk. The typical
> frequency of myelin reactive T-cells in the blood of a patient with MS
> is about 1 to 2 per million. Eliminating this small fraction of T-cells
> from a person's immune system has very little effect.
>
> Since Tovaxin is autologous and posses little health risk, if a small
> portion of patients show improvement (10%), it will get fast tracked.
> The current drug escalation trials have show that it is safe and almost
> all of the patients have shown improvement.
> ----------------------------
> Hi to all,
>
> I am in an FDA trial for an MS vaccine. The vaccine appears to have
> arrested my disease and has done the same for the other people in the
> study. I have two small websites that show a timeline of events. The
> first one is www.ihavems.com It starts with the first injection and
> goes for 18 months. My websites are little 10-page boilerplate sites,
> so my timeline continues on a second website www.timswellness.com from
> June 2004 to the present. I am a little behind on the second website. I
> haven't written anything since the end of February, but I will get back
> to it soon. My Dad and I work on it together.
>
> I am actually out doing things again. I just returned from a solo trip
> to see some friends in San Francisco. This is amazing, since two years
> ago, my parents were taking me from our home in Michigan to Houston in
> a wheelchair.
>
> Tovaxin is an autologous vaccine. That means they take some of my
> blood, cull out the T-cells and introduce them to human myelin. Those
> that react to the myelin are culled out and replicated. Once there are
> enough for the vaccine, about 45 million cells, the T-cells are
> irradiated so that they are still alive, but cannot reproduce. That is
> the vaccine.
>
> The vaccine is injected just under my skin, you can see some pictures
> at www.timswellness.com , and the body treats these T-cells as a
> foreign invader and makes antibodies to eliminate only these specific
> T-cells. These antibodies not only take out the T-cells from the
> vaccine, but also eliminate all of that same type of T-cell throughout
> my body.
>
> The body produces 2 to 3 trillion red blood cells per day. I am not
> sure how many T-cells are produced per day, but if 1 or 2 per million
> are troublemakers, that means there are hundreds of millions of myelin
> reactive T-cells floating around in the blood stream of someone with
> MS. A flare is when the body produces too many of these bad T-cells. No
> one is sure why this happens, but it may be caused by an upper
> respiratory infection, or a cold sore, or some other immune response
> that triggers the body to produce T-cells that mistake myelin as
> something bad.
>
> By eliminating these 1 or 2 per 1 million T-cells does not compromise
> the immune system, but it does eliminate all of the T-cells that
> destroy the myelin. No bad T-cells means no more attacks. Anyone on
> Tovaxin will need to get a booster twice a year to keep the antibodies
> at a level sufficient to continue to eliminate all of the myelin
> reactive T-cells as they are produced. This is just like a flu shot.
>
> I think about 30 to 40% of the damage that was done by the attacks has
> been reversed. The body will repair itself, as long as the attacks
> stop. I am helping myself by doing a lot of exercising and activities
> that improve my small motor skills.
>
> I am doing many things that I was no longer able to do. When I started
> the vaccine, my parent's were cutting my food and feeding it to me. I
> am able to cut my own food, and today, I peeled some shrimp. Realizing
> that I can again do something as insignificant as peel a shrimp really
> makes me feel good. I used to wonder why people got so excited to see a
> disabled family member regain some little ability, now I understand,
> and I understand why my family is trilled at even my smallest
> improvement.
>
> Best regards, Tim
>


.

Relevant Pages

  • Re: Whats the skinny on Tysabri?
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