Story at a glance
- There are no monoclonal antibodies currently authorized in the U.S. to fight a SARS-CoV-2 infection.
- A new antiviral drug received emergency authorization in Japan and will enter global phase 3 clinical trials.
- A paper published today introduces a “decoy” drug that targets the virus through a novel mechanism.
With no monoclonal antibody treatments available to fight the coronavirus, vulnerable populations may be at even higher risk this winter as COVID-19 cases start rising after the Thanksgiving holiday. There aren’t currently any monoclonal antibodies on the horizon to replace those that the Food and Drug Administration (FDA) has revoked authorization for, but there are potential antiviral drugs in the works that could help fight off infections.
Last week, the FDA officially paused the emergency authorization for the last remaining monoclonal antibody treatment: bebtelovimab from Eli Lilly.
Administered as an injection, monoclonal antibodies attach to the virus and block it from entering cells. This can help prevent more severe illness by reducing how much the virus can reproduce in the infected person’s body.
The FDA paused authorization because the treatment is not as effective against the newer omicron variants and subvariants that are now circulating as it was against earlier strains of the virus. Other monoclonal antibodies previously had their authorizations paused for similar reasons.
Several other medications aimed at combatting COVID-19 are still authorized. Evusheld, a combination of two monoclonal antibodies given as a pre-exposure prophylaxis (PrEP) for COVID-19, seems to still be effective at preventing severe illness against some omicron variants, although the FDA published a warning that it may be less effective against new variants.
The treatment differs from monoclonal antibodies that are given to patients who are infected with the virus. In addition, Evusheld is meant for people who are moderately or severely immunocompromised, so it is not available for everyone.
Additionally, recent studies suggest that the antiviral drug Paxlovid is effective at reducing the rate of hospitalizations by 51 percent. Like most monoclonal antibody treatments, antiviral drugs are prescribed once a diagnosis has been made and an infection is confirmed or highly likely.
However, not everyone can take Paxlovid, as it can be risky for people who have mild to moderate kidney disease, are on dialysis or have severe liver disease.
Several other potential antiviral treatments are currently in development. A new drug described in a paper published in Science Advances on Wednesday could be a game changer.
Researchers at the Dana-Farber Cancer Institute developed a “decoy” drug that mimics the receptor on the surface of cells that the virus needs to bind to and infect the cell. This receptor is called the ACE2 receptor.
This ACE2 decoy causes an irreversible structural change in the coronavirus once the virus binds to it. The structural change affects the spike protein, which is the part of the virus that is also targeted by monoclonal antibodies and vaccines.
This drug is still in early stages of development and would need to go through clinical trials.
Another drug, developed by Shionogi, has received emergency authorization in Japan. It works by targeting specific enzymes the virus needs to replicate.
The pill, called Xocova — or its generic name ensitrelvir fumaric acid — is meant to be taken once a day for five days after prescribed. This is fewer pills than Paxlovid, which requires three pills twice a day for five days.
Patients in phase 2/3 clinical trials, mostly in Japan, tolerated the drug well, according to a press release. The company plans a global clinical trial and will continue to collect data on efficacy and safety.
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