Monoclonal antibodies are advancing as treatments for COVID-19.

While vaccines and convalescent plasma transfer have garnered much of the attention around immune therapy for COVID-19, another type of immune therapy has recently gained interest. This therapy uses monoclonal antibodies administered into individuals through an IV as either a prophylactic or treatment for COVID-19 infection. 

The concept here is similar to that of convalescent serum infusions, where antibodies in the infusion bind and inactivate the virus. The difference is that every antibody molecule is the same (hence, a mono [one] clone) so that you are infused only antibodies that bind and neutralize the virus. This is theoretically an improvement over convalescent serum therapy as it markedly reduces the amount of antibody necessary and increases the likelihood that the antibody that you infuse will have the ability to neutralize the virus during an infection.

Monoclonal antibody therapy has become very commonplace in human therapeutics. Monoclonal antibodies against inflammatory proteins are some of the leading therapies for asthma, allergies, and autoimmune disease such as rheumatoid arthritis and psoriasis. In addition, monoclonal antibodies are now part of the most promising treatment for tumors helping the immune system kill cancer cells.

Two new reports have highlighted approaches that use monoclonal antibodies against the SARS-CoV-2 virus to prevent or treat COVID-19. Regeneron has started a human clinical trial of a cocktail of different antibodies that can inactivate the coronavirus. This approach is focused on treating people who are already infected with COVID-19. There are two different antibodies in the Regeneron mixture, and it is hoped that this will provide lifesaving interventions in patients with COVID-19.

Another report today from the University of Pittsburg identified a monoclonal antibody fragment that they constructed. It is able to inactivate the virus and treat infected animals. It has also been shown to protect hamsters from SARS-CoV-2 infection. They have started a company to commercialize this antibody.

Neither of these companies is the first to get a Covid-19 antibody therapy into human trials. Eli Lilly and AbCellera started testing their antibody treatment in humans June 1. There are a handful of other companies working on additional antibody therapies.

While these approaches are generating optimism, neither is a sure thing. Treatment of COVID-19 infection would seem to be the easiest target, but one would need to give the the monoclonal antibodies early on in the disease before the patient gets too ill that viral inactivation may not be useful (similar to the remdesivir antiviral drug trials). Prevention of infection would seem to be more difficult because you’d have to take these antibodies at some continuous interval to maintain high enough amounts in your blood to protect you against a new infection. 

Finally, neither of the monoclonal therapies is without potential complication. Individuals can develop an immune response to these antibodies that either prevents them from working or causes severe allergic reactions. This has been well documented with therapeutic antibodies used to treat arthritis or other disorders. But as a single dose “magic bullet,” anti-SARS-CoV-2 monoclonal antibodies do hold promise.