KELLY MCEVERS, HOST:
The dream of gene therapy took a big step forward today. A Food and Drug Administration advisory committee unanimously endorsed the first gene therapy for an inherited disorder. NPR health correspondent Rob Stein is with us now for the details. Hey, Rob.
ROB STEIN, BYLINE: Oh, hey there.
MCEVERS: So let's start by talking about the disease that this gene therapy would be used to treat. Tell us about it.
STEIN: Yeah, it's called retinal dystrophy. And it's a genetic disorder that causes progressive damage to the retina in the eye often starting in childhood and slowly leading to blindness. It's a pretty rare disease. There are maybe about 6,000 cases worldwide. A couple of thousand of those are in the United States.
MCEVERS: And so these 6,000 people could benefit from gene therapy. But what does that mean, gene therapy? How does it work?
STEIN: Yeah, it's pretty interesting stuff, Kelly. So what they did is scientists took a harmless virus, and they genetically engineered it to make a - to make it into kind of like a delivery drone to ferry a healthy version of the gene that's defective in this disease into patients' eyes. And then doctors inject billions of these genetically modified viruses into the patients' eyes. That gets the healthy gene into the retina, where it pumps out a healthy version of an enzyme that's needed for healthy vision.
MCEVERS: How well does it work?
STEIN: Well, so far it looks like it's working really well, you know? Now, it's only been tested on a couple of dozen patients so far, but it seemed like almost all of them benefited to some degree, or at least most of them did. For some of them, it was just kind of modest improvement. But for others, their vision started to improve within days of getting these injections.
And it improved pretty dramatically within a year. You know, they went from being legally blind - you know, they were unable to walk around without a cane or someone guiding them. And they were - a lot of them were totally trapped in their houses at night because they had terrible night vision. And then they suddenly could do things they could never do before.
Like, during today's hearings, some kids got up, and some teenagers described that they could for the first time do things like read, ride a bike, play sports, play baseball, see their parents' faces. You know, and one young man got up and said for the first time, he could go out at night, look up at the sky and see the stars and the moon. It was pretty dramatic, and it really opened up the world for a lot of these people.
MCEVERS: Wow. So an FDA committee endorses it. So does that mean that it is safe? I mean, are there side effects? And how long might those last?
STEIN: Yeah, yeah. So far it seems pretty safe. You know, there sometimes were some complications that occurred from the procedure of injecting something into the eye, the physical procedure. But so far there are no signs at all that the gene therapy itself was dangerous, that injecting a gene into the eye caused any significant complications.
Now, so far it does seem to be lasting, but that's a big question. How long will it continue to last? These patients have been followed for maybe three years, and it's continuing to work. But they're going to have to follow these patients for longer to be sure.
MCEVERS: Any idea of how much it would cost?
STEIN: So that's a big question. There's a lot of speculations by analysts that it could be pretty expensive. You know, any - some of the newer treatments that have been approved recently have cost hundreds of thousands of dollars. And so you can imagine if this costs, you know, $400,000 or $500,000 for each eye, we're talking about potentially a million-dollar treatment. But the company hasn't said yet what it's going to charge for this product.
MCEVERS: What does today's news say about where gene therapy stands overall?
STEIN: You know, scientists and doctors have been dreaming about doing gene therapy for decades, but early on, there were some real setbacks. Some patients died, and people thought it was never going to happen. But recently there was another treatment approved, and it looks pretty promising for a number of conditions. So it looks like we might be at a turning point here.
MCEVERS: NPR health correspondent Rob Stein, thanks a lot.
STEIN: Oh, sure. Nice to be here.
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