Targeting the receptor axl by bemcentinib prevents SARS-CoV-2 infection

ABSTRACT

Background: SARS-CoV-2 enters host cells via an interaction between viral spike protein and cellular ACE2. However, in common with other enveloped viruses, apoptotic mimicry may also assist cell entry phosphatidylserine (PS) exposed on the viral envelope interacts with cellular PS receptors leading to efferocytosis. The PS receptor, GAS6 bound to AXL, has also been shown to suppress type I interferon (IFN) responses. AXL is the predominant cellular PS receptor expressed on airway-derived cell lines. We hypothesized that the clinical-stage, AXL kinase-specific inhibitor, bemcentinib, inhibits SARS-CoV-2 infection and represents a potential therapy for COVID-19. Methods: Viral infection and host transcriptional responses to infection with SARS-CoV-2 or a VSV pseudovirion bearing SARS-CoV-2 spike were measured in human airway epithelial cell lines, engineered hACE2-expressing A549 lung cancer cells, and Vero E6 cells treated with bemcentinib or protease inhibitors. Studies also measured the effect of bemcentinib on SARS-CoV-2 binding and internalization into cells. The in vivo effect of bemcentinib (50mg/ kg, orally, twice daily) was assessed in C57BL6/J mice infected with the murine coronavirus, mouse hepatitis virus (MHV, 500 or 5x104 infectious units intraperitoneally). Viral titers and loads in liver were evaluated at day 5 postinfection. Spleen and liver were harvested to evaluate type 1 IFN-related gene expression changes. Results: Bemcentinib prevented infection by SARS-CoV-2 as assessed by viral transcripts in RNAseq studies as well as viral load in qRT-PCR analysis of human lung epithelial, A549-hACE2 and Vero E6 cells. Bemcentinib reduced virus internalization without affecting virus binding. Further, bemcentinib inhibition correlated well with inhibitors that block endosomal acidification and cathepsin activity, consistent with AXL-mediated SARS-CoV-2 uptake into endosomes. In vivo, bemcentinib significantly inhibited murine MHV liver titers and virus load and significantly enhanced signatures of type I IFN response. Conclusion: The orally bioavailable AXL inhibitor bemcentinib demonstrated potent antiviral effects in pre-clinical SARS-CoV-2 and other coronavirus models. These data support two ongoing phase 2 studies (EudraCT 2020-001736-95 [UK] & CTRI/2020/10/028602 [India] and DOH-27-092020-6170 [South Africa]) of bemcentinib for the treatment of COVID-19 in hospitalized patients, including those requiring supplemental oxygen and/or non-invasive ventilation, but not intubation.