On May 20, 2020, Atossa Therapeutics announced the successful results from in vitro testing of AT-H201, Atossa’s proprietary COVID-19 drug candidate. The preliminary study results show that AT-H201 inhibits SARS-CoV-2 infectivity of VERO cells in a laboratory culture, which are the standard cell types being used to study infectivity of the coronavirus. SARS-CoV-2, sometimes called the coronavirus, is the COVID-19 infectious agent.

AT-H201 is designed to act as a “chemical vaccine” by binding to the surface of the coronavirus and inhibiting the ability of the virus to enter a cell (“viral infectivity”). Significant findings from the testing include:

• AT-H201 components inhibited SARS-CoV-2 from infecting VERO cells in a laboratory culture.
• This is the first submicromolar inhibitor of SARS-CoV-2 identified to date in published literature, meaning that a relatively small amount of the drug is necessary to result in an anti-viral effect.
• Testing was also performed on remdesivir, an anti-viral medication being studied by others for use in COVID-19 patients, and the generic anti-malaria drug hydroxychloroquine, which is also being studied by others in COVID-19 patients. In these laboratory tests, the components of AT-H201 were found to be at least four-times more potent than remdesivir and at least twenty-times more potent than hydroxychloroquine. Potency was measured by microscopic examination of the cytopathic effect caused by SARS-CoV-2 in VERO cells.

The testing was conducted on behalf of Atossa by a leading academic research institute. Atossa planned to publish a manuscript of these test results. Successful in vitro tests do not guarantee similar results from in vivo studies, including in human clinical trials. Additional safety and efficacy studies must be successfully completed and regulatory approvals must be obtained before AT-H201 may be commercialized.