Medical trials are beginning to test two treatments and one preventative for this strain of Ebola circulating.

SCOTT DETROW, HOST:

For weeks, Ebola has been spreading in the Democratic Republic of Congo with no specialized treatments. That changed today. The first patient received an experimental treatment as part of clinical trials testing two drugs. Health officials hope these could help turn the tide against an outbreak that has already sickened more than 1,400 people and killed more than 430. NPR global health correspondent Jonathan Lambert is here with the latest. Hi, Jon.

JONATHAN LAMBERT, BYLINE: Hey, Scott.

DETROW: So this outbreak is new, but Ebola is not new. Why aren't there drugs available already?

LAMBERT: So there are approved treatments for Ebola, but not for the kind of Ebola that's spreading now. It's a rarer species called Bundibugyo. It's only caused two other outbreaks before this one - in 2007 and 2012. And it's pretty different than the more common species, and so it's not clear whether existing treatments will work, hence the clinical trials.

DETROW: Tell me more about these drugs that they're testing now.

LAMBERT: So there are two, and both would be given intravenously through an IV. One is a drug that you might remember from COVID. It's an antiviral called remdesivir. It's made by the American drug company Gilead Sciences. During the pandemic, it was used to treat patients in the hospital - to somewhat mixed effect. But it was actually developed to work against lots of different kinds of viruses, including Ebola.

DETROW: OK, what about the other drug?

LAMBERT: It's a monoclonal antibody with the catchy name of MBP134. Monoclonal antibodies are basically lab-made proteins that are designed to mimic the immune system's natural defenses. This one was designed from antibodies from a patient infected with a different species of Ebola, but there is some lab data to suggest that it could work against Bundibugyo. The drug is made by a US company called Mapp Bio. It got lots of support from the U.S. government in developing the drug, and the U.S. government is donating all the doses necessary to do the clinical trial.

DETROW: So how will the trial actually work?

LAMBERT: So researchers will be testing whether each drug alone, as well as the two drugs in combination, improve survival in Ebola patients. And they'll compare that with patients who get the kind of basic supportive care that's available now - things like replacing lost fluids through an IV. Right now, there's only one clinic that's enrolling patients in the trial, but health officials say that they plan to expand to more clinics in the coming weeks.

DETROW: Any sense how long it would take before researchers know whether these drugs are working?

LAMBERT: So that depends on a few factors. Here's WHO's research and development lead Vasee Moorthy at a press conference this morning.

(SOUNDBITE OF PRESS CONFERENCE)

VASEE MOORTHY: From what we see at the moment, this is going to take some time. So we shouldn't expect that this is going to be over in weeks. It will take some months. It could go even into next year. It could be that we need over a thousand patients enrolled in the trial until we get a definitive answer. That will be earlier if there's a very high efficacy from the trial.

LAMBERT: In other words, if the drug is super effective, that'll become pretty clear pretty quickly. And the lower the effectiveness, the longer it'll take. But there's also another wrinkle. This species of Ebola appears to be slightly less deadly than other species. If that's truly the case, it could also lengthen the trial since it'll be tougher to tell whether people are getting better because of the drug or whether they would have gotten better on their own without the drug.

DETROW: So let's just assume optimism, assume that the trial shows these treatments are effective. What difference could that make in the outbreak?

LAMBERT: An effective treatment would be really huge. It would help reduce the death toll in this outbreak that really shows no signs of slowing down. But that'll only happen if patients can actually access the drug, which is a real question. Prices and availability will be negotiated in the coming months between governments and drug companies, and WHO says that they're trying to expand access as much as they can.

DETROW: NPR's Jonathan Lambert, thanks so much.

LAMBERT: Thank you.

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