Dr. Andy

Reflections on medicine and biology among other things

Friday, March 04, 2005

FDA blocks promising therapy

This is actually old news, but the FDA continues to block potentially life-saving therapy for patients with severe immune deficiencies.

Patients with Severe Combined Immune Deficiency (SCID) basically are born without any adaptive immune system, leaving them vulnerable to all sorts of infections, including many, like Pneumocystis jiroveci (nee carinii) (don't get me started on how much I hate when they change microbes names), which you or I can fight off w/o problems

Patients either get curative therapy or die. If they are lucky enough to have a sibling who is a full HLA match (basically this means they share important markers on immune cells) they can almost always be cured by a bone-marrow transplant which gives them their sibs immune system. But if they don't have a full match, things are tougher. Most will get a 1/2 identical transplant from a parent, but these, called haploidentical, have a lot more problems. There is the risk of the tranplant recognizing the host as "foreign" and attacking it (graft versus host disease). Also it takes a lot longer to regenerate the immune system and the reconstitution is less complete.

So we need better treatment for these kids. A group in Paris took out blood stem cells from patients with a certain form of SCID and used a virus to introduce the gene they were lacking (this was for one of the major forms of SCID, there are a number). They then grew the cells up and put them back in the kids and it worked in almost all (8/10) the kids.

Unfortunately, a rare form of leukemia developed in one of the kids, which was thought to be incredibly bad luck (the gene being introduced happened to land right next to a gene that can cause cancer). But as a second, and now a third child have developed leukemia, perhaps it is more than bad luck. There have been other, smaller trials for the same and other forms of SCID and as of yet, none of these kids have gotten leukemia. And one of the first 2 kids to get leukemia was treated and probably cured.

But was the FDA really right in shutting down other gene therapy trials. I think not. Every decision about treatment must weigh risks and benefits.

Allowing Vioxx to be marketed to every American with a headache or sore back, despite questions about its cardiovascular risks (and that is being generous) was stupid.

But these kids don't have better options. If they don't get some curative treatment they will die. Sure they can get haploidentical transplants, but these have lots of problems as I noted above and many will likely die. And at least some of the suspended trials use different viruses, which probably (but not 100%) means a lower risk of the same leukemia.

I think the benefits (curative therapy for a horrible disease) outweigh the risks (possibility of getting another horrible disease), or at least warrant going forward with the trials.

UPDATE: the original LA times article, which is MUCH better is here. The Paris group has treated 17 kids, 3 got leukemia, but most (probably 14 or 15) had good response. Trust me, for this disease, that is great.


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