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Covid antibody treatments on track for FDA authorization, but are they a cure?

Even if ultimately approved and proven effective, there won't be enough of the medications for everyone who needs them.

In the past 24 hours, two drugmakers have asked the Food and Drug Administration to grant emergency use authorizations for their experimental antibody therapies for Covid-19.

Currently, patients must be in clinical trials for the chance to get those potentially beneficial drugs. An EUA would broaden availability to patients who are not enrolled in such studies — as was the case with President Donald Trump.

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The announcements from drug manufacturers Regeneron and Eli Lilly came within hours of Trump making public pleas to drum up support and enthusiasm for the medicines — referring to the antibodies as a "cure," despite a lack of evidence backing up such a claim.

The president, who received Regeneron's antibody therapy last week as part of his overall treatment for Covid-19, touted the drug (as well as Eli Lilly's similar therapy) in video messages posted on Twitter on Wednesday and Thursday.

In one video addressed to senior citizens, Trump suggested that he "could have walked out" of the hospital the day after getting the drug.

Monoclonal antibodies are lab-manufactured antibodies, meant to mimic the body's immune response and help prevent the virus from replicating.

It is impossible to know which, if any, of the multiple drugs the president received while hospitalized with Covid-19 helped. Doctors also gave Trump the antiviral drug remdesivir and a steroid called dexamethasone.

But in another video, the president largely dismissed the other therapies, calling the Regeneron drug "unbelievable."

"To me it wasn't therapeutic, it just made me better," he said. "I call that a cure."

No drugs for Covid-19, however, have been proven to be a cure for the disease. Clinical trials of the treatment Trump received are still ongoing.

Dr. Anthony Fauci said there is a "reasonably good chance" that the Regeneron drug made a significant difference in the president's course of the illness. But, he added, it's impossible to extrapolate one person's apparent success to the general population.

"When you only have one, you can't make the determination that that's a cure," Fauci, the head of the National Institute of Allergy and Infectious Diseases, said on MSNBC's "Andrea Mitchell Reports" on Thursday. "You have to do a clinical trial involving a large number of individuals compared either to a placebo or another intervention."

One of Regeneron's monoclonal antibody trial sites is located at the UW Health in Madison, Wisconsin, where enrollment for the clinical trials has "spiked" in the past week.

"It's obviously easier when you can talk about a study in terms of, 'this is a trial investigating the same cocktail that the president received.' Everybody knows what you're talking about," Dr. William Hartman, who is leading the UW trial, said.

While the boost in public interest has provided momentum for the trial, Hartman stressed the importance of completing the studies on monoclonal antibodies.

As a doctor, "I do think that it is going to be a good medicine, and you want it available to patients when they need it," Hartman said. "But at the same time, as a researcher, you want to be able to have all the data, so it's as clean a picture as possible."

Last month, Lilly released partial results from a trial of its monoclonal antibody drug, which suggested it could help keep patients with mild to moderate forms of the illness from getting sick enough to be hospitalized. Regeneron reported last week that early evidence suggested its treatment also appears to help mild to moderate cases of Covid-19.

Dr. Todd Rice, an associate professor of medicine at the Vanderbilt University Medical Center in Nashville, Tennessee, said the data are promising but still quite early.

"We want to get treatments to patients as fast as we can," Rice, who is not involved in the trials, said. But he added that there needs to be a "balance" between having enough information to make sure a medicine is helping, but not hurting, patients.

"We're starting to get those data, but I think it's pretty early for us to feel confident that we know what both the good and the bad of these treatments are," Rice said.

If the FDA ultimately authorizes the Lilly or the Regeneron antibody treatments for emergency use as expected, it will help physicians access the drug outside of clinical trials.

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Neither company has released full results from large clinical trials for peer review, which is considered standard for scientific research. But both companies have already begun manufacturing tens of thousands of doses.

Lilly expects to have 100,000 doses available this month, and said the supply could reach as many as 1 million doses by the end of the year. Regeneron said it already has doses for about 50,000 patients, and predicted it could produce enough to treat 300,000 people "in total within the next few months," according to a company statement.

But with upwards of 40,000 new Covid-19 cases each day in the U.S., it's clear the projected supply of those monoclonal antibodies will be insufficient to meet demand.

"Even if monoclonal antibodies do work, there's not going to be enough of them," Dr. Caleb Alexander, a professor of epidemiology and medicine at the Johns Hopkins Bloomberg School of Public Health, said. "There is going to be a mad scramble for these products."

Alexander said the gaps that are sure to exist mean the nation should not abandon evidence-based public health measures to curb the spread of the coronavirus, including physical distancing, contact tracing and wearing masks.

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