- In an effort to fight SARS-CoV-2, and with the likely increase in other coronaviruses, experts are looking for existing drugs that can fight these infections.
- A leprosy drug called clofazimine has shown promise against SARS-CoV-2 in hamsters.
- Clofazimine blocks the ability of SARS-CoV-2 to enter cells and replicate via RNA.
- The drug has also shown promise against Middle East respiratory syndrome (MERS) in laboratory experiments.
SARS-CoV-2, which is the virus that causes COVID-19, is not the only zoonotic coronavirus. In fact, it is the third to emerge since the turn of the century. It was preceded by severe respiratory syndrome (SARS) in 2003 and MERS in 2012.
There is likely to be more coronavirus if the recent past is any indication. However, there are currently not many drugs that can fight them effectively.
Researchers have been racing to identify existing drugs that could be useful in this fight, with a team last year identifying 21 existing drugs as promising. Among them was a leprosy drug called clofazimine, which has been shown to be effective against SARS and MERS in laboratory experiments.
A new study by researchers at the Sanford Burnham Prebys Medical Discovery Institute in San Diego, CA, and the University of Hong Kong at Pok Fu Lam suggests that it may also be useful in the treatment of COVID-19.
Clofazimine exhibits antiviral properties against SARS-CoV-2 and limits the extreme inflammatory response that commonly occurs with COVID-19.
The study was submitted to peer review and will soon appear in an edited form in the journal Nature.
If the researchers confirm the effectiveness of clofazimine, experts can immediately implant the drug against SARS-CoV-2 and COVID-19.
The Food and Drug Administration (FDA) has already approved it for use against leprosy and is on the World Health Organization (WHO) Model List of Essential Medicines. Experts have thoroughly examined the safety of the drug, although it is not currently available for sale in the United States.
The study’s senior co-author, Dr. Sumit K. Chanda – of the Sanford Burnham Prebys Immunity and Pathogenesis Program – says: “Clofazimine is an ideal candidate for a COVID-19 treatment. It is safe, affordable, easy to make, taken as a pill and can be made available globally. “
Dr. Chanda explains, “We hope to test clofazimine in a phase 2 clinical trial as soon as possible for people who are positive for COVID-19, but not hospitalized,” adding:
“As there is currently no outpatient treatment available for these individuals, clofazimine may help to reduce the impact of the disease, which is particularly important now, as we see new variants of the virus emerging and against which current vaccines appear less effective.”
In the study, the researchers administered clofazimine to hamsters with SARS-CoV-2 and prophylactically (preventively) to other hamsters who did not yet have the virus.
Both groups that the researchers treated with clofazimine had less SARS-CoV-2 in their lungs after taking the drug.
Clofazimine also prevented the inflammatory, often deadly, reaction that commonly occurs in humans. This is called a “cytokine storm”.
The study’s co-author, Dr. Ren Sun, from the University of Hong Kong, reports: “Animals that received clofazimine had less lung damage and lower viral load, especially when they received the drug before infection.
Dr. Sun adds: “In addition to inhibiting the virus, there are indications that the drug also regulates the host’s response to the virus, which provides better control of infection and inflammation.”
The study suggests that clofazimine fights SARS-CoV-2 by doing two things: blocking the virus from entering cells and disrupting replication of the virus’s RNA.
The researchers also found that clofazimine, when administered to hamsters, worked synergistically with remdesivir. This is the most well-known drug currently in use as a treatment for COVID-19.
Because clofazimine is affordable and easy to make, it can help to stretch the limited – and comparatively expensive – supply of remediate.
Considering experts’ concerns about future coronaviruses, it is equally exciting that clofazimine appears to prevent MERS replication in human lung tissue in vitro.
“Potentially more importantly, clofazimine appears to have pan-coronavirus activity, indicating [that] it can be an important weapon against future pandemics, ”says the study’s senior co-author, Dr. Kwok-Yung Yuen, of Infectious Diseases at the University of Hong Kong.
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