Leprosy Drug Inhibits Coronaviruses Including SARS-CoV-2

According to a Nature study published today, the leprosy drug clofazimine exhibits potent antiviral activities against coronaviruses, including SARS-CoV-2, and prevents the cytokine storm response associated with severe COVID-19.

"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 globally available," says co-senior author Sumit Chanda, Ph.D., from Sanford Burnham Prebys Medical Discovery Institute. "We hope to test clofazimine in a Phase 2 clinical trial as soon as possible for people who test positive for COVID-19 but are not hospitalized."

Clofazimine was initially identified by screening one of the world's largest collections of known drugs for their ability to block the replication of SARS-CoV-2. Chanda's team previously reported that clofazimine was one of 21 drugs effective in vitro at concentrations that could most likely be safely achieved in patients.

In this study, the researchers tested clofazimine in hamsters that were infected with SARS-CoV-2. The scientists found that clofazimine lowered the amount of virus in the lungs, including when given to healthy animals prior to infection. The drug also reduced lung damage and prevented cytokine storm.

"The animals that received clofazimine had less lung damage and lower viral load, especially when receiving the drug before infection," says co-senior author Ren Sun, Ph.D., professor at the University of Hong Kong. "Besides inhibiting the virus, there are indications that the drug also regulates the host response to the virus, which provides better control of the infection and inflammation."

Clofazimine also worked synergistically with remdesivir, the current standard-of-care treatment for people who are hospitalized due to COVID-19, when given to hamsters infected with SARS-CoV-2. These findings suggest a potential opportunity to stretch the availability of remdesivir, which is costly and in limited supply.

"Potentially most importantly, clofazimine appears to have pan-coronavirus activity, indicating it could be an important weapon against future pandemics," says co-senior author Kwok-Yung Yuen, M.D., from the University of Hong Kong, who discovered the coronavirus that causes severe acute respiratory syndrome (SARS). "Our study suggests that we should consider creating a stockpile of ready-made clofazimine that could be deployed immediately if another novel coronavirus emerges."