Pyronaridine Tetraphosphate Efficacy Against Ebola Virus Infection in Guinea Pig

Abstract

31The recent outbreaks of the Ebola virus (EBOV) in Africa have brought global visibility to 32 the shortage of available therapeutic options to treat patients infected with this or closely 33 related viruses. We have recently computationally identified three molecules which have 34 all demonstrated statistically significant efficacy in the mouse model of infection with 35 mouse adapted Ebola virus (ma-EBOV). One of these molecules is the antimalarial 36 pyronaridine tetraphosphate (IC 50 range of 0.82-1.30 µM against three strains of EBOV 37 and IC 50 range of 1.01-2.72 µM against two strains of Marburg virus (MARV)) which is 38 an approved drug in the European Union and used in combination with artesunate. To 39 date, no small molecule drugs have shown statistically significant efficacy in the guinea 40 pig model of EBOV infection. Pharmacokinetics and range-finding studies in guinea pigs 41 directed us to a single 300mg/kg or 600mg/kg oral dose of pyronaridine 1hr after 42 infection. Pyronaridine resulted in statistically significant survival of 40% at 300mg/kg 43 and protected from a lethal challenge with EBOV. In comparison, oral favipiravir (300 44 mg/kg dosed once a day) had 43.5 % survival. The in vitro metabolism and metabolite 45 identification of pyronaridine and another of our EBOV active molecules, tilorone, which 46 suggests significant species differences which may account for the efficacy or lack 47 thereof, respectively in guinea pig. In summary, our studies with pyronaridine 48 demonstrates its utility for repurposing as an antiviral against EBOV and MARV, 49 providing justification for future testing in non-human primates. 50 51 52 4 Importance 53There is currently no antiviral small molecule drug approved for treating Ebola Virus 54 infection. We have previously used machine learning models to identify new uses for 55 approved drugs and demonstrated their activity against the Ebola virus in vitro and in 56 vivo. We now describe the pharmacokinetic properties of the antimalarial pyronaridine in 57 the guinea pig. In addition, we show that this drug is effective against multiple strains of 58 EBOV and MARV in vitro and in the guinea pig model of Ebola virus infection. These 59 combined efforts indicate the need to further test this molecule in larger animal efficacy 60 studies prior to clinical use in humans. These findings also may be useful for 61 repurposing this drug for use against other viruses in future. 62 63

Tilorone: a Broad-Spectrum Antiviral Invented in the USA and Commercialized in Russia and beyond

“…A recent species comparison of metabolism of tilorone demonstrated N-deethylation and mono-oxygenation was higher in guinea pig relative to both mouse and human (33). The species-liver microsome stability relationship increased in the order of guinea pig, non-human primate, mouse, followed by human (33). The differences in metabolic stability between species could also account for any differences in efficacy observed between the mouse and guinea pig models of EBOV treated with tilorone.…”

Toward the Target: Tilorone, Quinacrine, and Pyronaridine Bind to Ebola Virus Glycoprotein

“…The copyright holder for this preprint (which this version posted May 28, 2020. ; https://doi.org/10.1101/2020.05.26.118182 doi: bioRxiv preprint Prior work on pyronaridine has demonstrated that it has promising in vitro activity against EBOV as well as excellent in vitro absorption, distribution, metabolism and excretion (ADME) properties and a very long half-life across mice and humans (21). It also has statistically significant in vivo efficacy in mice and guinea pigs infected with EBOV (24). While the mechanism to date was unclear, it has been shown to inhibit lysostracker suggesting a lysosomotropic effect (25).…”

“…It has excellent in vitro ADME properties and was recently demonstrated to have potent in vitro inhibition of EBOV as well as efficacy in mouse infected with EBOV (22). Interestingly this molecule did not demonstrate efficacy in the guinea pig EBOV model likely due to the significant species differences in metabolism when compared to mouse (24). Tilorone has also demonstrated in vitro inhibition of MERS (26) and is under evaluation as a potential treatment for other coronaviruses such as SARS-CoV-2 (23) and has shown a low M IC 50 (27).…”

“…Pyronaridine tetraphosphate also demonstrated significant activity in the guinea pig adapted model of EBOV infection (24) and is currently used as an antimalarial in combination with artesunate (Pyramax®). Most recently pyronaridine was shown to be a potent lysosomotropic agent while artesunate which is also active against EBOV in vitro was not (25).…”