President Donald Trump's medical team threw him a Hail Mary pass shortly after he tested positive to the coronavirus, says an Australian expert.
It came in the form of an infusion of Regeneron's REGN-COV2, a highly experimental and unproven drug prescribed alongside two other main treatments.
Mr Trump received a single 8-gram cocktail of antibodies tailor-made to treat the virus, the White House physician said.
It was an unprecedented move to give such an important person a drug so early in its development, said Professor John Rasko, head of the Department of Cell and Molecular Therapies, Royal Prince Alfred Hospital.
"In this case it's just a hunch, it's a wild kick to see whether or not they can get a goal — a Hail Mary pass, as they say," Professor Rasko said.
Mr Trump has since left the Walter Reed Medical Hospital, where he was being treated for COVID-19.
White House physician Dr Sean Conley said Mr Trump was running a high fever and has received supplemental oxygen twice.
"They really, really want to reduce the viral load in the President," Professor Rasko said.
"It tells you that the greatest medical minds in the United States of America concluded the President should receive this highly experimental drug in order to minimise the chances that he would suffer the consequences of SARS-COV-2 infection.
"It's unprecedented that a sitting President of the United States, and leader of the free world, would receive a highly experimental drug that is as yet not proven in terms of the combination of three drugs that the President received, or indeed in and of itself."
How does the Regeneron cocktail work?
Antibodies are proteins made by the body's immune system that recognise, bind and neutralise an invading virus.
They can also be manufactured in a lab, like the drug Mr Trump took.
When taken, they give the body a better chance at fighting a virus, University of Western Australia clinical immunologist Michaela Lewis said.
"As the virus is replicating in your body, having this drug on board would lower your viral load, meaning your immune system is faced with less virus to fight," Dr Lewis said.
"That gives you a better chance of having a better outcome."
The drug designed by Regeneron uses two lab-manufactured antibodies designed to bolster the immune system's ability to recognise and neutralise the coronavirus that causes COVID-19.
It cut down the viral load in the patients who took part in the trial, the company said in a report published just last week.
"The greatest treatment benefit was in patients who had not mounted their own effective immune response, suggesting that REGN-COV2 could provide a therapeutic substitute for the naturally-occurring immune response," said Regeneron president and chief scientific officer George Yancopoulos.
But more trials are needed to determine if the drug actually works, Dr Lewis said.
"Obviously it would have to be tested in a randomised control trial because it may be efficacious on a case by case basis but it has to stand the test that it is doing better than no drug at all," she said.
How did Trump get the drug?
Mr Trump was given the drug on compassionate grounds, the New York Times reported.
Compassionate use cases are when patients are granted access treatments which are still in clinical trials.
Regeneron's chief executive Leonard Schleifer said Mr Trump's medical staff contacted the company for permission to use the drug.
"All we can say is that they asked to be able to use it, and we were happy to oblige," he said.
Dr Lewis said it would be difficult to determine whether or not the drug helped Mr Trump.
"It's very difficult to say looking at just one case, and we're only being given some of the information," she said.
"You can just speculate whether he will get better with or without this drug, I don't think we'll probably ever know because I think each patient's individual journey is of course different.
"It's difficult to predict who will do bad and who will do well, we've got some pointers, but unfortunately, it's very difficult to tell and it's often only in the second week of this disease that we will find out [if] a rapid deterioration occurs."
Side effects unknown
Mr Trump was also given the common steroid dexamethasone and the antiviral drug Remdesivir as part of his treatment.
Professor Rasko said it is not clear whether the combination can cause any adverse side effects.
"It tells you that this is a promising avenue, in the opinion of his doctors, to pursue," he said.
"If it works it works, if it doesn't work he could suffer side-effects but it's in their estimate that they'll take the risk as it comes."
Mr Trump was also given zinc, aspirin, vitamin D, melatonin and his daily aspirin, according to Dr Conley.
Similar antibody trials underway
Another US-based company, Eli Lilly and Company, also has clinical trials for antibody treatments underway, as well as UK-based company AstraZeneca.
Researchers at the Walter and Eliza Hall Institute were given $500,000 by Victorian Government to continue developing antibody-based therapies in August.
Professor Rasko said he working with collaborators at Peking University for a similar treatment developed by Chinese-based pharmaceutical company BeiGene.
He said 10 people in Brisbane were the first to receive the BeiGene treatment a few weeks ago.
"We will administer in the first patients with COVID-19 later this month," he said.
"It's not like we're missing out on anything, Australia is well and truly helping to develop these specific drugs."
