key: cord-333140-cdikbi1l authors: Zhao, Helong; Mendenhall, Michelle; Deininger, Michael W. title: Imatinib is not a potent anti-SARS-CoV-2 drug date: 2020-09-30 journal: Leukemia DOI: 10.1038/s41375-020-01045-9 sha: doc_id: 333140 cord_uid: cdikbi1l nan protease-inhibiting effect. Although the precise mechanism remains unclear, these data provide a rationale for testing imatinib as an antiviral against COVID-19 in clinical trials. Three prospective randomized clinical trials are underway to study the therapeutic efficacy of imatinib vs. standard of care or placebo in patients with COVID-19, including NCT04357613 (France), NCT04394416 (USA), and EudraCT2020-001236-10 (The Netherlands). However, the anti-SARS-CoV-2 efficacy of imatinib in a standard viral replication assay has not been demonstrated. We tested the effects of imatinib and asciminib, a highly specific and potent ABL inhibitor binding to the myristate pocket of the kinase domain [7] , on SARS-CoV-2 infection and replication in the naturally susceptible ACE2 + human Caco-2 cells [5] . Using pseudotyped virus with SARS-CoV-2 S protein as the envelope proteins, we first analyzed single-round viral entry/infection. Imatinib did not show an inhibitory effect on SARS-CoV-2 entry/infection at concentrations up to 10 μM, while asciminib showed a mild effect that is not statistically significant by ANOVA analysis (Fig. 1a) . We then performed the standard viral replication assay using the USA-WA1/2020 strain of SARS-CoV-2 to test imatinib and asciminib in a blinded fashion, including remdesivir as a positive control. Neither imatinib nor asciminib demonstrated in vitro activity toward SARS-CoV-2 replication (Fig. 1b, c) , while remdesivir exhibited potent inhibition of SARS-CoV-2 replication within the non-toxic concentration range (Fig. 1d ). Therefore, our data indicate that, within clinically achievable dose ranges, imatinib and asciminib have no significant effect on SARS-CoV-2 infection and replication. This is in accordance with the reported low potency of imatinib against SARS-CoV, with EC 50 at 9.82 μM in Vero E6 cell cultures [3] , which is also unachievable with standard imatinib dosage (400 or 800 mg/day). Conflicting data have been published regarding the incidence of COVID-19 in CML patients. A retrospective Chinese study reported a higher incidence of infection in CML patients than in the general public. In contrast, a prospective study from the Netherlands and a survey by the Italian CML network showed very low incidences, and suggested a potential protective effect of TKIs [8] [9] [10] . Population-based studies and comprehensive viral testing will be required to resolve these discrepancies. Even though we find no evidence that imatinib is an antiviral drug, it may still hold promise for the treatment of COVID-19. Similar to SARS and septic acute lung injury, lethal COVID-19 is mainly manifested as acute respiratory distress syndrome caused by overt immune activation and inflammatory cytokine storm [11] . Imatinib has immunemodulatory effects [12, 13] , and on-target inhibition of ABL1/ 2 was shown to mitigate acute lung injuries in various preclinical models [14] . Imatinib mediated inhibition of cytokine receptor signaling (PDGFR, c-Kit and CSF1R) may also reduce cytokine-induced inflammatory response and tissue injury. Therefore, it is possible that imatinib will show clinical benefit for COVID-19 because of its immune-modulatory effects. Indeed, rapid improvement of pulmonary infiltrates was reported in a patient with COVID-19 treated with imatinib [15] . These data support additional prospective investigations into the potential beneficial effect of imatinib and possibly other ABL inhibitors on COVID-19, but provide insufficient evidence for the off-label use of imatinib in patients with COVID-19. Our data indicate that any beneficial effects should not be attributed to direct antiviral activity. were added to 5 wells of a 96-well plate with 60-80% confluency. Three wells of each dilution were infected with virus, and two wells remained uninfected as toxicity controls. SARS-CoV-2 was added to achieve a multiplicity of infection (MOI) of~0.002, and supernatant viral titer was quantified after 3 days by a standard endpoint dilution CCID50 assay. Remdesivir was tested in parallel as a positive control. Coronavirus S proteininduced fusion is blocked prior to hemifusion by Abl kinase inhibitors Abelson kinase inhibitors are potent inhibitors of severe acute respiratory syndrome coronavirus and middle east respiratory syndrome coronavirus fusion Repurposing of clinically developed drugs for treatment of Middle East respiratory syndrome coronavirus infection Genomic characterisation and epidemiology of 2019 novel coronavirus: implications for virus origins and receptor binding SARS-CoV-2 cell entry depends on ACE2 and TMPRSS2 and is blocked by a clinically proven protease inhibitor The ReFRAME library as a comprehensive drug repurposing library and its application to the treatment of cryptosporidiosis Discovery of asciminib (ABL001), an allosteric inhibitor of the tyrosine kinase activity of BCR-ABL1 Prevalence of COVID-19 diagnosis in Dutch CML patients during the 2020 SARS-CoV2 pandemic. A prospective cohort study Chronic myeloid leukemia management at the time of the COVID-19 pandemic in Italy. A campus CML survey COVID-19 in persons with chronic myeloid leukaemia Clinical characteristics of 138 hospitalized patients with 2019 novel coronavirusinfected pneumonia in Wuhan Targeting nonmalignant disorders with tyrosine kinase inhibitors Imatinib: the narrow line between immune tolerance and activation Targeting Abl kinases to regulate vascular leak during sepsis and acute respiratory distress syndrome Imatinib for COVID-19: a case report Imatinib is not a potent anti-SARS-CoV-2 drug Acknowledgements The author would like to thank Thomas O'Hare for valuable feedback on the manuscript. This work was supported in part by NCI CCSG grant P30CA42014-31 to the Huntsman Cancer Institute and NIH grant R01CA178397 to Thomas O'Hare and MWD.