Ex Vivo Validation of Six FDA-Approved Non-Receptor Tyrosine Kinase Inhibitors (NRTKIs) as Antivirals to Pandemic and Seasonal Influenza A Viruses

Influenza viruses are important respiratory pathogens that cause substantial morbidity and mortality annually. In addition to seasonal influenza outbreaks, new emerging influenza A viruses (IAV) can cause pandemic influenza outbreaks. Apart from effective vaccines, there is a need for better treatment options to combat infections with these viruses when vaccines are not available or show reduced efficacy (e.g., in immmunocompromised patients). The limited range of licensed antiviral drugs and emergence of drug-resistance mutations highlight the need for novel intervention strategies like host-targeted antivirals. Repurposing FDA-approved kinase inhibitors may offer a fast-track for a new generation of host-targeted antivirals. Small molecule kinase inhibitors (SMKIs) can inhibit replication of viruses and improve survival in vivo; however, no SMKI has been approved for clinical use against IAV infections. In the present study, we tested eight non-receptor tyrosine kinase-inhibitors (NRTKIs) used to treat cancer and autoimmune diseases for their antiviral potential. Six of those potently inhibited virus replication (≥1,000-fold) in A549 cells infected with either A(H1N1)pdm09 or seasonal A(H3N2) strains. These compounds were validated in a biologically relevant ex vivo model of human precision-cut lung slices (hPCLS) to provide proof of principle and show efficacy against contemporary seasonal and pandemic IAVs. We identified the steps of the virus infection cycle affected by these inhibitors and assessed the effect of these NRTKIs on the host response. Considering their established safety profiles, our studies show that the use of these NRTKI shows promise and warrants further development as an alternative strategy to treat influenza virus infections. ### Competing Interest Statement The authors have declared no competing interest.