Improved in vitro Efficacy of Baloxavir Marboxil Against Influenza A Virus Infection by Combination Treatment With the MEK Inhibitor ATR-002

Abstract

Currently, all available antiviral drugs against influenza virus (IV) that target the virus proteins directly, like Baloxavir acid (BXA), lead to viral resistance. Therefore, cellular mechanisms and factors essential for IV replication are promising antiviral targets. As IV strongly depends on the virus-induced Raf/MEK/ERK signal pathway for efficient generation of infectious progeny virions, this pathway represents an important target. We aimed to determine whether the MEK inhibitor ATR-002 (PD0184264) is able to impair replication of BXA-resistant influenza A virus (IAV) and whether a treatment combining BXA and ATR-002 improves the therapeutic efficiency in vitro. A549 cells infected with different IAV strains including BXA-resistant variants were treated with ATR-002 or BXA and the effect on virus titer reduction was determined. The synergistic effect of ATR-002 and BXA was also analyzed using different evaluation methods. The data demonstrated that ATR-002 has a significant and dose-dependent inhibitory effect on IAV replication across different strains and subtypes. IAV with the PA-I38T mutation shows resistance against BXA, but is still susceptible toward ATR-002. The combination of ATR-002 and BXA exhibited a synergistic potency reflected by low combination index values. In conclusion, we show that ATR-002 permits to counteract the limitations of BXA against BXA-resistant IAV. Moreover, the results support the use of ATR-002 (i) in a mono-therapy, as well as (ii) in a combined approach together with BXA. These findings might also apply to the treatment of infections with IAV, resistant against other direct-acting antiviral compounds.

Citraconate inhibits ACOD1 (IRG1) catalysis, reduces interferon responses and oxidative stress, and modulates inflammation and cell metabolism

“…As described previously 34 , MDCK-II cells (American Tissue Culture Collection, catalogue no. CRL-2936) were cultured in 96-well plates and grown overnight at 37 °C in a humidified 5% CO 2 incubator.…”

Influenza antivirals and animal models

“…Previous studies also showed that combinations of BXA/BXM and either NAIs or favipiravir had increased antiviral effects against pdmH1N1 and H3N2 IAVs compared with single-drug treatment [55]. BXM-resistant variants emerge readily during treatment with up to 120-fold reduced drug susceptibility (Table 1) [56,57]. The PA I38T mutation has been shown to increase resistance to BXM in vitro and in vivo [58].…”

“…BXM‐resistant variants emerge readily during treatment with up to 120‐fold reduced drug susceptibility (Table 1) [56,57]. The PA I38T mutation has been shown to increase resistance to BXM in vitro and in vivo [58].…”

In vivo antiviral efficacy and immune dampening effect of zapnometinib emphasize a dual therapeutic potential against COVID-19

“…This prompted us to analyze whether inhibition of the pathway would also lead to inhibition of SARS-CoV-2 replication. Indeed we could show that zapnometinib (ATR-002, PD 0184264), an oral MEK inhibitor, not only demonstrated antiviral activity against influenza virus 22,23 but also against SARS-CoV-2 in vitro 24 . Interestingly, the inhibitor also led to the reduction of expression of some virus-induced cytokines in infected cells 24 , although the relevance of this observation has still to be examined in vivo.…”

“…Thus, inhibition of this pathway may interfere with overshooting immune responses. In addition, we previously demonstrated that targeting the cellular Raf/MEK/ERK signaling pathway leads to viral load reduction and protects mice from a lethal viral challenge during infection with another live threatening respiratory virus, the influenza virus [21][22][23] . This prompted us to analyze whether inhibition of the pathway would also lead to inhibition of SARS-CoV-2 replication.…”