MDL-001: an Oral, Direct-Acting Universal Antiviral for Influenza-Like Illness (ILI) and Chronic Hepatitis

Endemic viral respiratory illnesses caused by influenza, RSV, and coronaviruses impose a global disease burden of hundreds of millions of infections and hundreds of thousands of deaths annually. Chronic hepatitis B and C infections persist in 254 million and 58 million people worldwide, respectively. No approved therapy addresses these viruses simultaneously. MDL-001 is an oral, direct-acting, broad-spectrum antiviral targeting the Thumb-1 allosteric site of viral polymerases. Here, we report MDL-001 inhibits influenza A/B, RSV, SARS-CoV-2, endemic human coronaviruses, and hepatitis B/C/D viruses with nanomolar EC90 potency in vitro. MDL-001 demonstrated equivalent in vivo efficacy to oseltamivir against mouse-lethal influenza A virus infection, reducing lung viral load by 2.6 log10 and preventing weight loss and mortality. MDL-001 demonstrated equivalent symptom reduction to subcutaneous remdesivir after SARS-CoV-2 infection. MDL-001 treatment reduced SARS-CoV-2 lung viral titers by 2.9 log10, superior to literature reported 1.4 log10 and 1.0 log10 reductions for nirmatrelvir and molnupiravir, respectively. MDL-001 reduced HCV viremia by 3.3 log10, equivalent to sofosbuvir. Oral MDL-001 reduced plasma HBV surface antigen by 2.5 log10, exceeding tenofovir alafenamide from Day 8 through Day 21. MDL-001 demonstrated an in vitro EC50 of 79.4 nM against infection with RSV strain A2, a 416-fold improvement over literature-reported ribavirin. Oral pharmacokinetics studies demonstrate MDL-001 is rapidly absorbed and partitioned into Lung (Kp=39-52) and Liver (Kp=71-104) tissues. MDL-001 produced no treatment-related adverse events across 376 animals and showed no hERG, Ames genotoxicity, or micronucleus safety issues. These findings support MDL-001 as a broad-spectrum, direct-acting non-nucleoside antiviral clinical candidate.