AB Science SA announced publication of a peer-reviewed article titled ‘Masitinib is a broad coronavirus 3CL inhibitor that effectively blocks replication of SARS-CoV-2’ in the journal Science. The article reports on research that identifies masitinib as a broad antiviral agent capable of treating SARS-CoV-2 (the virus that causes COVID-19), including demonstration of in vivo activity in mice, with efficacy maintained, in vitro, against SARS-CoV-2 variants of concern. Research led by Professor Savas Tay and Dr. Nir Drayman from the Pritzker School for Molecular Engineering (University of Chicago, USA) screened a library of 1,900 clinically safe drugs and identified masitinib as the most potent inhibitor of the main target responsible for virus reproduction, a protease called 3CLpro. Drugs targeting viral 3C-like protease are an attractive therapeutic option for COVID-19, in part because they are considered less vulnerable to the development of SARS-CoV-2 drug resistance; however, no such drugs targeting 3C-like protease are yet registered for use in the treatment of COVID-19. This direct-acting antiviral mechanism of action distinguishes masitinib from many other COVID-19 drugs, including polymerase inhibitors or monoclonal antibodies. Also reported for the first time are data on the effectiveness of masitinib as an anti-SARS-CoV-2 drug in animals. Mice infected with SARS-CoV-2 and then treated with masitinib showed >200-fold reduction in viral titers in the lungs and nose, as well as improved overall lung pathology and significantly reduced levels of key pro-inflammatory cytokines. Overall, results showed that masitinib rapidly and effectively reduced SARS-CoV-2 viral load in mice (reducing >99% of the viral load on day 6), reduced inflammatory signatures, and showed potential benefits for survival and clinical scores. Remarkably, masitinib was also effective, in vitro, against all tested variants of concern, including the rapidly spreading Alpha, Beta and Gamma variants. Results also showed that, in vitro, masitinib is potent against multiple corona- and picorna- viruses (human pathogens that cause a range of diseases including the common cold, meningitis, hepatitis and poliomyelitis). Thus, masitinib is a relatively broad-spectrum antiviral with potential activity against multiple viruses that rely on 3CL protease to complete their life cycle. Recently, AB Science signed an exclusive licensing agreement with the University of Chicago to conduct research for the prevention and treatment of COVID-19 with masitinib and other AB Science proprietary drugs [2]. Under this agreement, AB Science supplied masitinib and more than 130 other AB Science proprietary drugs that have demonstrated activity against SARS-CoV-2 main protease 3CL-Pro via virtual screening methodology, and in return will benefit from the proprietary research platform of the University of Chicago.