AUDIE CORNISH, HOST:
For the first time, scientists have used the powerful new gene-editing technique called CRISPR to try to treat sick people in the U.S. NPR health correspondent Rob Stein broke this news. He's here in the studio to tell us the details.
ROB STEIN, BYLINE: Oh, hey there.
CORNISH: What can you tell us first about the patients who were treated?
STEIN: Yeah, so there were two patients who were treated so far. Both have cancer. One has the type of blood cancer known as multiple myeloma. And the other has a type of tissue cancer known as sarcoma. And both had suffered relapses after undergoing other standard cancer - kinds of cancer treatments before undergoing this experimental treatment with CRISPR.
CORNISH: So you said it's experimental. How did doctors use CRISPR to do the treatment here?
STEIN: Yeah, so what they did is they removed key immune system cells - they're known as T cells - from each patient. And then they used CRISPR to edit the DNA inside these T cells in the lab. And then they infused the genetically modified cells back into the patients' bodies. And the idea is that these edits in the DNA would kind of turn these T cells into - you can sort of think of them as guided missiles that would zero in and attack then destroy any cancer cells in their bodies.
CORNISH: What do we know about how well it worked?
STEIN: Yeah, so unfortunately, they're not releasing, really, any information so far about how well it worked. What we do know is that these patients were treated as part of the first study that was approved in this country to try to use CRISPR to treat people with a medical problem. It's being conducted at the University of Pennsylvania. And the university is only saying that these researchers are going to wait to release any details at some point in the future at a medical meeting or by publishing them in a scientific journal.
CORNISH: Forgive me for saying this, but that sounds cagey (laughter). Can you talk about why they might be holding back?
STEIN: Yeah. So, you know, these scientists - they're being very careful. They know how new and experimental this is. And therefore, it's got - has some risks. Whenever you try something this new and this powerful this early, you never know what's really going to happen when you try it in patients. And this study is actually being done at the University of Pennsylvania.
And it's the same university where, in the early days of gene therapy, a young man did die in a very early gene therapy study that set the field back, like, a decade. So the last thing these researchers want to do is, you know, do anything risky. They're taking it very carefully, being very slow. They're going to follow these patients for a long time to see if it's safe and how well it's working.
CORNISH: All right. There's a lot at stake here. And this isn't the only study, I understand, that's trying to use CRISPR to treat diseases. What else is going on?
STEIN: Yeah, yeah. It's actually a really exciting time for - in the world for CRISPR and medical treatments right now. There's about a half a dozen studies that are - have been going in China for cancer for a while. And now another half a dozen or so are being launched in Europe, in the United States and in countries like Canada that try to treat a variety of diseases. In the first one are blood disorders. One is known as beta thalassemia. That first patient was treated there in Germany recently. And then there's - another trial is going to be starting soon in this country to try to use CRISPR to treat sickle cell disease. So it's a lot happening right now with CRISPR and diseases.
CORNISH: And it sounds like it's still early days.
STEIN: It is early days. And that's really important to point out; that these are very preliminary studies. They're aimed primarily at trying to find out if this is safe. But they are going to follow these patients to see how well it's working for clues. We might get a sense of that by the end of this year or maybe early next year.
CORNISH: That's NPR's health correspondent Rob Stein.
Thanks for your reporting.
STEIN: Oh, sure - nice to be here.
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