Why monoclonal antibodies are expensive and hard to make in the fight against COVID-19.
What is monoclonal antibody therapy?
When a patient undergoes monoclonal antibody therapy, they are infused with high concentrations of antibodies engineered to fight the coronavirus.
Regeneron and Ely Lily are pharmaceutical companies that have been given an FDA emergency use authorization for their cocktail of monoclonal antibodies. A third company, GlaxoSmithKline, has an FDA emergency use authorization for a single antibody infusion.
These therapies cost about $2,000 a dose, which includes only about a gram of each antibody. They're expensive, in part, because they aren't traditional chemical drugs.
Each antibody takes months to identify, isolate and scale and thousands of gallons of nutrients to produce.
The therapy can be injected with a needle or administered intravenously.
What are antibodies?
Your body makes its own antibodies in response to infections. The main difference between a monoclonal antibody and your body’s antibodies is diversity.
Each antibody is like a unique key in search of a lock. Keys find their compatible locks, they bind to it, tagging it for the immune system to attack. Antibodies also “neutralize” viruses, preventing them from attaching to cells to infect them.
Dr. David Sullivan, an infectious disease physician at Johns Hopkins Hospital explained that antibody was about the third the size of the spike protein that the coronavirus uses to attach to human cells. "So you just have to have three or four (per spike protein) to prevent it from interacting with a cell. But if you have one antibody on one virus that virus is still going to be able to infect."
During a COVID-19 infection, your body makes hundreds — if not thousands — of different antibodies each tuned to a different part of the virus. Each is made by a single, unique immune cell. No other immune cell, not even those that are closely related, can produce that exact antibody.
Over time, the most successful antibody-making cells edit their antibodies to be better fits while cloning themselves to increase their manufacturing power. This is like your body figuring by trial and error out which key fits a lock.
Fundamentally, your body always makes more than one version of antibody against the same infectious agent.
OK, so what are monoclonal antibodies?
Unlike your body's natural spectrum response, monoclonal antibodies are grown in a lab from a single clone. That’s where the name “mono” comes from. The antibodies are all the same from clones of the same cell.
The second difference is between monoclonal antibody and your own home-grown antibody is speed. You need several days to mount a natural antibody response, or fewer if you are vaccinated. But administered monoclonal antibodies start working immediately.
"The first part of the disease is nothing more than the replication of SARS-COV2 in your nose," said Myron Cohen MD, director of the Institute for Global Health and Infectious Diseases at the University of North Carolina-Chapel Hill. "We are trying to check the disease in your nose before severe disease and death, and monoclonal can clearly do that."
How effective are monoclonal antibodies against COVID-19?
When a patient undergoes monoclonal antibody therapy, he or she is effectively getting a very small slice of someone else’s COVID-19 immune response. For that to work on a disease, you need lots more of that one artificial antibody than your body would normally make for itself.
Sullivan likened it to using water to put out a fire.
"Vaccines are like a little bit of water on the matches beforehand. It doesn't take much to prevent a fire," he explained.
Monoclonal antibodies are like using a small amount of water to put out a lit match. Those drops will work on a match, but not on a big fire.
As the infection gets worse, monoclonal antibodies are less and less effective.
"If I put a cup of water on an actual fire, it doesn't do as much," he said.
