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Gene Therapy Holds Promise for Cure for Parkinson's

Aired August 19, 2003 - 19:36   ET


DARYN KAGAN, CNN ANCHOR: In his many public appearances, actor Michael J. Fox helped put a face on Parkinson's disease. And while a cure has yet to be found for the debilitating illness, an ambitious experiment got under way at New York's Weill-Cornell Medical Center yesterday. It could relieve some symptoms of Parkinson's. This one involves gene therapy. Supporters will tell you the treatment holds great promise, critics are saying this experiment may be too dangerous.
To help us sort out the pros and cons, let's bring in our medical correspondent, Dr. Sanjay Gupta from Atlanta. Sanjay, good evening.


KAGAN: Let's talk -- oh, you go ahead.

GUPTA: Go ahead.

KAGAN: Well, I was just going to say, talking about Parkinson's disease, you have well over a million people who clearly have this disease who are concerned about it. No cure out there. Looking for some kind of relief.

GUPTA: That's right. And so there is a lot that people know about Parkinson's disease. There is some good treatment out there already, which gives us gene therapy that much a higher standard to live up to. You said about a million people, million and a half people, that's right. There are a lot of famous faces out there. You've already mentioned some of them. Certainly Muhammad Ali, Michael J. Fox, the pope, the former Attorney General Janet Reno, but the more common face of Parkinson's disease is a 60-year-old, as likely to be a man as a woman, with significant rigidity and otherwise significantly healthy.

Take a look at some of the symptoms there. That is the tremor, that is one of the hallmarks of Parkinson's disease. Add to that now rigidity and some slowness of movement, as you see here, and you have some of the hallmarks of Parkinson's disease.

What happens in the brain? That is really the key to figuring out how to treat this. And there's actually an animation that shows what happens. There are neurons that are constantly firing in the brain, but sometimes these neurons don't fire as well because they actually die off, and they don't produce something in the brain known as dopamine. If you remember one thing about Parkinson's disease, remember that there is not enough dopamine in the brain, and that's why people develop these symptoms. So, Daryn, you're absolutely right, there are a lot of treatments out there. They are really hinging a lot of hopes on gene therapy, though, because it's more than a treatment, it's potentially a cure -- Daryn.

KAGAN: Well, and let's talk about gene therapy. This is certainly is considered in many other diseases besides Parkinson's. But it's also has to be considered perhaps deadly and at the very least controversial.

GUPTA: You know, it makes a lot of sense, gene therapy, if you think about it. Most diseases, if you really trace them back to their roots, have a genetic basis for why the diseases occurs. So gene therapy was all the rage. It was so exciting. Lots of hopes pinned to it about 10 years ago, and then you started to see some disasters happen fairly early on.

One of the most notable ones was actually just a few years ago, about four years ago, Jesse Gelsinger (ph), was an 18-year-old involved in a clinical trial studying gene therapy. He actually had injections of a particular form of gene therapy, and within a few days, actually, his body went into multiple organ system failure, and he subsequently died. You can imagine the sort of lashout that came at gene therapy because of this. Certainly didn't want people dying. This was supposed to be the thing that actually cured people.

There's been sort of a timeline in history now, if you look back at gene therapy, since a lot of these trials started, about 400 trials started about 10 years ago when all the promise was there in gene therapy. If you look back now in 1990, actually, was the first gene therapy trial. 1999 was the first death. That was the one we were just talking about. 2002, there was another disaster. Two child participants actually developed leukemia-like conditions with gene therapy. In January of 2003, all of the clinical trials sponsored by the FDA were halted. And now, Daryn, the trial that we're talking about now for Parkinson's, one of the first trials in a while actually looking at gene therapy to treat Parkinson's -- Daryn.

KAGAN: And just real quickly, a timetable here, Sanjay. As we said, a lot of people have loved ones or are dealing with it themselves. Right now we're talking about one man who's had the treatment and 12 others who were approved. That sounds like a long way for this to become a conventional therapy.

GUPTA: A simple way to look at it, Daryn, they are in phase one clinical trials right now. There are three phases to clinical trials. The first phase to see if it's safe; the second, to see if it's effective, and the third, to see if it's more effective than what exists today. That could be several years away.

There are some disadvantages. If you look at gene therapy and what may be some of the holdups here, one is that there are some very good existing treatments, and those existing treatments, again, make it much harder for gene therapy, it gives it a much higher standard to live up to. The virus by which the genes get into the brain may be hard to control, can cause all sorts of brain swelling and problems. And you just don't know the long-term effects yet. So those are some of the barriers still to getting this gene therapy through -- Daryn.

KAGAN: Dr. Sanjay Gupta. Sanjay, you might want to stick around, because your alma mater is making news. We're going to be talking about a story coming up. I don't know if it's a course you've taken, but, well, stay tuned. You'll see what we're talking about.

GUPTA: All right, I'll stick around.


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