MADDIE SOFIA, HOST:

Hey, everybody. Here at NPR's SHORT WAVE, we are working to bring you a good amount of coronavirus coverage. But there's also lots of other important stuff going on in the world, and honestly, we thought you could use a little break. The science in today's episode got me pretty excited and, I dare say, a little hopeful. We'll be back with more coronavirus coverage tomorrow. OK. Let's have fun.

You're listening to SHORT WAVE from NPR.

Maddie Sofia here with NPR health correspondent Rob Stein. How's it going, Rob?

ROB STEIN, BYLINE: It's going great, Maddie. How are you doing?

SOFIA: Amazing...

STEIN: Great.

SOFIA: ...Because if you're here...

STEIN: Yeah.

SOFIA: We're talking about CRISPR.

STEIN: It's CRISPR time with Rob.

SOFIA: It's CRISPR time with Rob.

STEIN: Doesn't get any better than that.

SOFIA: You are always bringing us these amazing CRISPR exclusives.

STEIN: Oh, Maddie, what can I say? CRISPR is my thing, you know? I'm even thinking about naming our next dog CRISPR. But wait. Wait. Wait. Hold on a second. I misremembered. Our kid wants a cat, so - CRISPR the cat. That's...

SOFIA: That's a good name.

STEIN: It's got a good ring to it, don't you think?

SOFIA: It's unique. All right. Tell me why CRISPR is so awesome.

STEIN: It's really cool because CRISPR is this really powerful gene editing technique that allows doctors to make really precise changes in our genetic codes, and so it's got incredible potential for treating lots of diseases.

SOFIA: Right. It is actually not an exaggeration to say that CRISPR could revolutionize medicine in the future. And today you have brought us another CRISPR milestone.

STEIN: Yeah. Maddie, get this. For the first time, scientists have used CRISPR to try to edit a gene while the DNA is still inside the body.

SOFIA: Which is wild because until now, all CRISPR treatments for things like cancer or sickle cell disease - doctors had to remove the cells they wanted to change from the patients' bodies, edit them in the lab and then put them back in.

STEIN: Right. But this time, hopefully, the editing will take place inside the eye of a patient who is almost completely blind...

SOFIA: Wow.

STEIN: ...Due to a genetic disease called Leber congenital amaurosis. The experimental treatment was done by doctors at the Casey Eye Institute in Portland, Ore. The hope is that the CRISPR will edit or fix the mutated gene that caused the disease and potentially restore the patient's vision.

SOFIA: So today on the show, a new CRISPR treatment that happens within the body. If it works, it could open up new avenues of treatment for diseases that were previously off-limits to CRISPR.

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SOFIA: OK, Rob, in order to understand the treatment, we need to understand a little bit more about this disease.

STEIN: Yeah. So it's called Leber congenital amaurosis, and it primarily affects the retina. That's the tissue in the back of your eye that helps detect light and color. Most people who are born with it start to lose their vision right away and end up really only being able to detect light from dark and maybe a little bit of motion. It's a rare condition, but it's still one of the most common causes of blindness in kids.

SOFIA: Right. And in the patient we're talking about today, the disease is caused by a genetic mutation that affects a very important protein that our retinas need to develop properly. With this disease, either the body doesn't make enough of that protein or it makes a protein that just doesn't work.

STEIN: Exactly. So the doctors want to go in and use CRISPR to snip out that genetic mutation so the body can make that very important protein that will hopefully heal the sick cells in the retina, giving the patient the ability to see.

SOFIA: Wild.

STEIN: Here's Eric Pierce. He's a doctor at the Massachusetts Eye and Ear Hospital in Boston. He's running the study.

ERIC PIERCE: If we can fix the underlying genetic defect, we have the potential to restore vision to people who never had normal vision before. It would indeed be amazing.

SOFIA: Amazing is right.

STEIN: Yeah.

SOFIA: So how does the CRISPR treatment get delivered to the cells in the eye?

STEIN: Well, Maddie, it's probably what you're thinking. First, the surgeon cuts a tiny hole into the patient's eye.

SOFIA: I don't like it.

STEIN: I know. I know. Then the surgeon dripped three little drops of liquid under the retina. Those drops contained billions of viruses that were genetically engineered to carry the genetic coding for making the CRISPR tool right inside the eye.

SOFIA: OK. So it's in there, and the modified viruses actually infect the cells in the retina, right?

STEIN: Right. Exactly. And the genetic coding the virus is ferrying to the cells, it carries instructions for manufacturing the individual parts of the CRISPR inside the cells.

SOFIA: OK. Then what?

STEIN: So once the CRISPR machinery is inside the eye, the idea is that it becomes the surgeon - kind of like a tiny, little, microscopic surgeon inside the retina that's going to perform microscopic DNA surgery on the cells.

SOFIA: Right. CRISPR literally - this is so cool - slices out the genetic mutation that is causing the blindness, and voila.

STEIN: Voila. And hopefully, this would be a one-time treatment that would restore vision for a lifetime.

SOFIA: OK, Rob. Let's take a step back. Tell me why it's such a big deal that CRISPR is being done directly inside the body instead of treating cells outside the body and putting them back in.

STEIN: Yeah. It is a big deal, and here's why. There are many other diseases where you can't really use CRISPR the way it's been used to treat them - by taking cells out of the patient's body, editing them and putting them back in - you know, brain diseases, like maybe some inherited forms of dementia, muscle diseases like muscular dystrophy.

SOFIA: Right. There are a lot of diseases where you either can't get to those cells or you can't take them out...

STEIN: Yeah.

SOFIA: ...For certain and put it back in.

STEIN: You can't do it that way. So the hope is that this could be the beginning of a whole new era of medicine where scientists edit people's genes while the DNA is still inside the body to treat their diseases. I talked to Francis Collins about this. He leads the National Institutes of Health.

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FRANCIS COLLINS: All of us dream of what time might be coming where we could apply this approach for thousands of diseases. This is the first time that's being tried in a human being, and it gives us hope that we could extend that to lots of other diseases if this works and if it's safe. This is a significant moment.

SOFIA: When the head of one of the largest research agencies in the world is excited about something, that's generally a good sign. OK. So, Rob, what happens next with our first ever CRISPR-inside-the-body patient?

STEIN: So this patient is the first in a small study that started at the Casey Eye Institute at the Oregon Health and Science University in Portland. And the first thing that doctors and scientists are looking for is, you know, is this safe? I mean, remember, nothing like this has ever been done before.

SOFIA: Right.

STEIN: So they're starting with a very low dose and an older patient who already can't really see very much, and they're only treating one eye. The idea here is to just make sure this doesn't backfire somehow...

SOFIA: Sure.

STEIN: ...And end up destroying whatever vision is left instead of helping. Here's Charles Albright. He's from Editas Medicine, one of the companies sponsoring the study.

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CHARLES ALBRIGHT: There's always a potential with any experimental medicine for things to happen that you don't anticipate. And so you always want to start in a situation where, if something unexpected did happen, the chances of it causing damage is the least that you can possibly make it.

SOFIA: So basically, this volunteer patient is the first. They're making sure it's safe, doesn't make things worse and hoping it helps.

STEIN: Right. So the scientists are going to keep a very close watch on this patient, who could start to see better within weeks. And if it does seem to be safe, they'll try it on other patients - maybe try higher doses - and, if it keeps looking safe and does seem to be working, eventually try it on younger patients, even kids, who have the best chance it might actually help them the most.

SOFIA: OK. Rob, NPR SHORT WAVE CRISPR correspondent, aka NPR health correspondent, you better come back here and tell us if it works, Rob.

STEIN: You got it, Maddie.

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SOFIA: A quick announcement - if you're looking for coronavirus news, NPR has just launched a new daily podcast for just that. It's called Coronavirus Daily, with new episodes released in the late afternoon every weekday. It's got NPR's latest reporting, features and interviews about the coronavirus pandemic all in one place. And, of course, you can also follow our coverage on your local public radio station, who, by the way, you should totally be supporting.

This episode was produced by Brit Hanson and edited by Viet Le. I'm Maddie Sofia. We're back with more NPR SHORT WAVE tomorrow.

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