Doctors are seeking to grow some of the body's most potent disease-fighting weapons in a test tube and deploy them against COVID-19.
The treatment, known as monoclonal antibody therapy, could serve as both a remedy for patients infected with the coronavirus that causes COVID-19 and a way to prevent infection in frontline health workers and other people at high risk.
At least six companies expect to be testing antibodies on COVID-19 patients this summer.
Monoclonal antibodies have proven to be powerful tools against ailments including cancer and rheumatoid arthritis. A new treatment against Ebola is under review at the U.S. Food and Drug Administration.
Antibodies have advantages over conventional drugs that put them near the front of the pack of new therapies under development against COVID-19. For one, producing them is relatively fast, thanks to technology developed in the last 10 to 15 years.
"The whole process, from getting a blood sample to having antibodies ready for the clinic, was about three months," said antibody sciences director Laura Walker at biotech company Adimab.
While safety testing is just beginning, Walker said antibody treatment is generally fairly safe.
"Everybody makes antibodies naturally," she noted.
And since they are based on a well-studied part of the body's defenses, Walker added, "the odds that a monoclonal antibody will be effective is quite high."
Antibodies are a key part of the immune system. They work by attaching themselves to an invading germ. In the case of viruses, this blocks the invader from entering a cell and causing an infection.
Skipping the vaccine
Vaccines trigger the same response. But since there is no vaccine for COVID-19, "we're skipping the vaccination step and we're directly making these antibodies," said Joe Jardine at IAVI, a nonprofit scientific research organization.
Most of the antibodies come from people who have recovered from COVID-19 infection. Their blood is full of them, which is why doctors are testing whether giving COVID-19 patients convalescent plasma — the liquid part of blood from recovered people — could treat or prevent infection.
But collecting enough plasma to treat large numbers of patients is labor intensive, and plasma must be screened for other diseases the donor may be carrying.
The blood of recovered patients is also full of the cells that produce antibodies. In recent years, technology has emerged that can sort through millions of these cells to find the ones that produce the most potent antibodies against an individual germ. These cells then form the basis of a manufacturing process to grow large quantities of antibodies.
Patients would receive the treatment by injection or intravenous drip.
So far, two companies have monoclonal antibody therapies undergoing clinical trials for hospitalized COVID-19 patients. At least four others are expected to begin testing this summer.
Antibodies also could be used to provide temporary, vaccine-like protection from infection.
"This would function as a stopgap" for health care workers or other vulnerable people while vaccines are being developed, Jardine said, or as prevention for older people who don't respond as well to vaccines.
Protection would likely last about a month, possibly six if the antibodies were modified.
Not just one virus
Walker's group has isolated several antibodies that block not only the coronavirus behind COVID-19 but also the one that caused the 2003 SARS outbreak and a related coronavirus found in bats.
The COVID-19 virus is the third coronavirus in less than two decades to emerge from the wild and kill humans. Many more are circulating in bats and other animals. As people increasingly move into wildlife habitats, humans are coming into contact with a growing number of viruses.
"It's almost certain we're going to see something like this happen in the future," Walker said. "What you want is not just an antibody that works against the current virus, but also against future, related viruses."
She hopes to start clinical trials later this year.