On a Saturday afternoon in March, as COVID-19 approached New York City, a dozen scientists crowded anxiously around a computer in the lab of a suburban pharmaceutical company. For weeks, they had fiercely drawn blood from early survivors around the world and from mice with human immune systems – all to test thousands of potential treatments.
Now it was time for results.
The screen flashed totals of glowing green dots, hundreds or thousands in most examples. Then they saw a pair of tens, a pair of twos, and finally zeros.
Investigators cheered and their boss sent champagne.
No dots meant no infected cells. The scientists had found antibodies that block the coronavirus.
This was the beginning of a drug that would eventually go into the arms of a US president and others fighting off COVID-19.
Antibodies are substances that the immune system makes to bind to a virus and help eliminate it, but it takes several weeks after infection or vaccination for the most effective to form. Drugs such as those used by these scientists at Regeneron Pharmaceuticals Inc. are designed to help right away, by providing concentrated doses of one or two antibodies that work best.
The drugs, delivered by IV, are being tested to prevent infection in high-risk people who cannot yet receive a vaccine, such as roommates of COVID-19 patients. They are also tried as a treatment shortly after infection to prevent serious illness.
They are some of the most complex drugs out there, made in a tedious, high-tech process with the risk of breaking down every step of the way. Unlike chemicals that are simply mixed in a lab, antibodies are extracted from living cells. Companies have used cells from an entire menagerie – monkeys, hamsters, mice, horses, cows, llamas.
Each drug starts with a single coronavirus survivor.
Eli Lilly, for example, teamed up with AbCellera, a company in Canada that got a powerful antibody from an early case there. GlaxoSmithKline and Vir Biotechnology found one in blood frozen for years in a Swiss lab from a survivor of SARS, another coronavirus that triggered a deadly outbreak in 2003.
Regeneron’s dual-antibody drug is unique: one came from a COVID-19 survivor in Singapore and the other from the company’s genetically modified mice.
People make hundreds or thousands of types of antibodies after infection, but “most of them are not very good” at blocking the coronavirus, said Christos Kyratsous, a microbiologist who helped lead Regeneron’s work. “You’re looking for the needle in the haystack” to find one that does, he said.
The search began in January, when Chinese scientists identified the new virus. Dr. Sumathi Sivapalasingam, a Regeneron scientist who had worked at the U.S. Centers for Disease Control and Prevention, began looking for blood samples from people who were infected early on long enough to have made good antibodies.
“We were essentially calling people from all over the world” – China, Thailand, the UK, Europe – with no luck, she said.
Out of the blue, they got a call from Dr. David Lye from the National Center for Infectious Disease in Singapore. He knew Regeneron had antibodies to Middle Eastern respiratory syndrome or MERS, a similar coronavirus disease. COVID-19 cases started to ramp up and “I was thinking what else there was to do” because no treatments had yet been shown to help, Lye said.
The scientists soon ruled out the use of the MERS antibodies, but agreed to find some for the new virus. Lye asked three of his patients – two men and a woman who had recovered from COVID-19 pneumonia – to donate blood.
It was unpredictable. Blood cells survive for about two days and the flight to New York takes 18 hours. The samples would then have to pass through customs and be driven to Regeneron’s lab in Tarrytown, New York.
“It was exciting” but terrifying, said Lye. “I was concerned whether a flight delay or an error en route would render the samples useless.”
“The blood was warm in the tube,” when a courier rushed it to Singapore airport, Sivapalasingam said.
It arrived on March 13, the day COVID-19 was declared a national emergency in the United States. Sivapalasingam was working from home until late when she received an email from colleagues at the lab.
“They jumped for joy because the cells were fresh and viable and perfect,” she said.
Meanwhile, others were working with what Regeneron’s CEO calls his “magic mice,” animals bred to have a human immune system. When they are vaccinated with a piece of the virus, they don’t get sick, but make “nearly identical antibodies to what humans would make,” Kyratsous said. It only takes 20 to 30 of these mice to develop a drug.
Blood from the mice and patients contains B cells and each makes a specific antibody that is carried on the surface. The goal is to find antibodies that attach to the virus and prevent it from infecting cells.
Scientists first screen the B cells by mixing them with some of the spiny protein that covers the virus and sorting out cells with antibodies that connect. Next, researchers decode the genetic recipes for each antibody. The genes are put into a type of hamster cell that is widely used in the drug industry because they grow very quickly and produce the antibody of choice as mini biofactors.
Then comes the big challenge: testing each antibody by mixing it with uninfected cells and a “pseudovirus” – a tame virus that has been modified to carry the spike protein and glow green when it enters a cell.
Each antibody goes into a well in a plastic grid container, such as a huge ice cube tray. A computer attached to a microscope counts how many cells in each well were infected to see how successfully each antibody blocked the virus.
These are the results that Kristen Pascal went to the lab on Saturday March 14 to get.
She remembered bringing “pizza and pie for Pi Day,” a day when scientists celebrate because 3, 1, and 4 are the first three digits of pi, an important number in math.
Kyratsous, other executives and company co-founder, Dr. George Yancopoulos, floated behind her chair as the computer counted glowing dots.
“I get maybe 1 and 2,000 green spots in every pit,” and some hit 10 and a few hit two, she said. When they saw some zeros, Yancopoulos ordered the champagne.
“We had really good antibodies,” she said. “We knew we were in shape, that we could really make a difference.”
Those antibodies were only from the mice. Two weeks later, the process was repeated on the human samples from Singapore.
In total, Regeneron tested more than 3,300 antibodies – pitting the finalists against each other like gladiators in the lab – before choosing two that bound to the spike protein in different places to make it more difficult for the virus to escape.
“There was a tremendous sense of relief from selecting the best antibodies … but it was very stressful because you can’t go back,” said Kyratsous. “These are the ones going into production.”
Dan Van Plew’s job is to take what he calls ‘the recipe’ from the Tarrytown lab, run it through his ‘test kitchen’ at Regeneron’s manufacturing facility near Albany, New York, and find out find out how it can be mass-produced as a medicine. It’s like making some craft cupcakes for a tasting and then getting a big wedding assignment, “so now I have to figure out how to make a thousand for a VFW venue,” he said.
First, the fast-growing hamster cells containing the genetic recipe for the chosen antibody are placed in a container called a bioreactor. “You’re trying to mimic a body,” keeping the cells at body temperature, bubbling air to provide oxygen, removing carbon dioxide, and delivering nutrients at the right rate for the cells to multiply, he explained.
They are gradually being moved into ever-larger bioreactors – “it looks like a really big microbrewery,” said Van Plew – until the cells are so densely packed that they switch from reproducing themselves to producing antibodies.
Contamination is a constant risk.
“At one point or another, I probably have 1,500 people touching the process, whether it’s touching the product or running a biorector,” and every car they drive, shoes they wear, or anything they touch, is a potential danger, he said.
When the work of the last bioreactor is done, the contents are purified to remove pieces of the cells, leaving only the antibodies, which are packaged in vials.
Production took 45 days – “light speed compared to standard process,” which is usually three to five months, he said.
Human studies began in early June. In October, President Donald Trump got the drug under “compassionate use” provisions, but there is no way to know if it did him any good, as most patients recover on their own and he has also undergone other experimental treatments. The Food and Drug Administration has allowed emergency use of Regeneron and Eli Lilly antibody drugs for mild and moderately ill patients who do not require hospitalization while the studies continue. Tests on critically ill, hospitalized patients were interrupted because of concerns that the drugs might not help in that situation.
Regeneron sells other antibodies against heart disease, cancer and other conditions. The 2012 MERS outbreak marked the first time a quick attempt was made to create one for an infectious disease. MERS did not appear to spread easily from person to person, “so we were very lucky as a society,” and the company never scaled up production, Kyratsous said.
When Ebola hit in 2014, Regeneron developed antibodies and did its first production in an outbreak situation. But it took nine months, and by then the cases were on the decline. In 2018, it took another outbreak to prove the value of that drug.
When the new coronavirus appeared, many of the same scientists were waiting.
“We knew exactly what to do … we had done this before,” said Kyratsous. “I feel like Regeneron was waiting for such a moment.”
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Marilynn Marchione can be followed on Twitter at http://twitter.com/MMarchioneAP
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The Associated Press Department of Health and Science is supported by the Science Education Department of the Howard Hughes Medical Institute. The AP is solely responsible for all content.