Tysabri is a fairly new MS treatment and differs from the other treatments in that it is a monthly infusion rather than a self-adminstered injection. Tysabri was fast-tracked by the FDA because the clinical trial results were incredible. Tysabri became available in 2004 and was pulled in March 2005 because of three deaths due to PML, progressive multifocal leukoencephalitis.
The way Tysabri works is that it makes the blood-brain barrier sticky so that the confused and rogue white blood cells are unable to cross the barrier to damage myelin in the brain, spinal cord and optic nerve. While this is remarkable there is danger that the central nervous system is somewhat vulnerable to infection, such as PML, because those same rogue fighter cells are unable to get to the infection to help fight it. And this my friends, is very dangerous.
After further review by the FDA Tysabri returned to market in July 2006 and it's been adminstered without incident until late yesterday when news broke after the US markets closed that two additional cases of PML have been diagnosed. One patient is at home and the other is in the hospital. I couldn't find any additional information about their current condition. I hope they recover quickly and completely.
Investors are skittish about the news and the stock has taken a beating this morning. This shouldn't be reason to pull Tysabri again but it should underscore the risk involved with powerful drugs.
2 years ago
4 comments:
Why do you think this isn't reason enough to pull it from the shelves?
The percentage of PML cases isn't great enough, imho, to take Tysabri off the market. I don't know the current number of patients receiving Tysabri but an old number I found was 5,000, so 2 patients in a pool of 5,000 is 0.04%. For me, that's a safe percentage. If it were to jump up to 1% then I'd say let's reevaluate.
xoxo
we have a friend undergoing clinical trials for cancer (kidney that spread to lymph nodes) and he apparently was on an intense level of chemo that actually nearly killed him; it was zapping the tumor but at the same time was burning up his organs at a very intense level. i think he's still glad he did the test treatment though bc everything else he'd done up to that point didn't do anything to help shrink the tumor.
it seems like a really fine line with these powerful drugs and treatments that are still in the trial stage. i guess i'd agree w/ you that .04% is a safe percentage, but then you still feel bad for those in the .04%... you know?
take care,
suzanne
Hi Suzanne,
I wish the best for your friend. I can't imagine how tough his journey has been but I can understand his desire to try a dangerous but potentially more effective treatment. If nothing had helped I would try the riskier treatment.
It's tough to decide what is an acceptable percentage of illnesses or worse resulting from new treatments. The 0.04% is a low number but you're right, that number represents two people who have gotten pretty sick and may not recover. To them and their families & friends it may as well be 100%.
Hopefully we'll see you all in the morning.
E.
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