Efficacy and Safety of Drug Combination Therapy of Isotretinoin and Some Antifungal Drugs as A Potential Aerosol Therapy for COVID-19 : An Innovative Therapeutic Approach

This is a small pilot study investigating whether there is any efficacy signal of combination therapy of Isotretinoin and some Anti fungal Drugs in COVID-19 treatment that warrants a larger Phase III trial, or any harm that suggests that such a trial should not be done. It is expected to produce statistically significant results in the major endpoints. The investigator will examine all of the biologic, physiological, and clinical data to determine whether a Phase III trial is warranted.

Primary efficacy analysis will be carried only on patients receiving at least 4 doses of active combination drug. Safety analysis will be carried out on all patients receiving at least one dose of active drug.

introduction

In Wuhan, Hubei Province, China, cases of acute respiratory infection were reported in December 2019.1,2 The Chinese Center for Disease Control and Prevention (CDC), initially reported that the cause of this disease is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), then it is founded to be a novel coronavirus.3Now, This disease, is designated by the WHO as coronavirus disease 2019 (COVID-19), which rapidly spreads to other cities of China, and has become a public health emergency of international concern (PHEIC) following its global spread. The clinical manifestations of COVID-19 are fever, cough, muscle pain, fatigue, diarrhea and pneumonia, and can cause death in severe cases.4China has reported 72436 cases of confirmed COVID-19 and 1868 fatalities through February 18, 2020.5 The innate immune system represents the first line of defense and initiates counteractive responses that protect the host from viral infection through evolutionarily conserved pattern recognition receptors (PRR) 6. PRRs include the membrane-bound Toll-like receptors (TLRs) and cytosolic sensors, such as retinoic acidinducible gene-I (RIG-I)-like receptors (RLRs), which sense RNA viruses 6. RIG-I specifically detects the intracellular double-stranded viral RNA bearing 5' triphosphate and panhandle structures to activate antiviral signaling7,8. Once a host is invaded by a virus, PRRs transmit signals to the downstream kinases that activate transcription factors, including IFN regulatory factor-3 (IRF3), nuclear factor κB (NF-κB), and ATF-2/c-jun, with the help of different adaptor molecules (MAVS/IPS-1/VISA/Cardif for RIG-I, TRIF for TLR3, and MyD88 for TLR7/8/9) to activate IFN production9,10,11.Viruses have evolved elaborate mechanisms to evade or inactivate the innate immune signaling pathway for their replication 12. Severe acute respiratory syndrome (SARS) is a highly contagious respiratory disease that appeared first in China in 2002 and has infected more than 8000 people worldwide and killed about 800 of those infected. SARS coronavirus (SARS-CoV) has a singlestranded, positive sense RNA genome of approximately 29.7 kb 13,14. Numerous studies have revealed that SARS-CoV develops an antagonistic mechanism to evade the antiviral activities of IFN 15 Infection with SARS-CoV-2 can lead to excessive production of pro-inflammatory cytokines, but the production of type I interferons, which are key antiviral mediators, is reportedly blunted; Previous studies suggested that SARS-CoV papain-like protease (PLpro) inhibits activation of the IRF3 pathway, which would normally elicit a robust IFN response, but the mechanism(s) used by SARS PLpro to inhibit activation of the IRF3 pathway is not fully known.16 As key components of the immediate antiviral response, type I interferons are crucial for restricting viral replication and spread, through autocrine and paracrine type I IFN receptor (IFNAR) signalling. Type 1 interferons have a broad antiviral activity in vitro and are currently evaluated in a clinical trial to treat MERS-CoV However, minimal amounts of IFNs have been detected in the peripheral blood or lungs of patients with severe COVID-19 17,18 In a mouse model of SARS-CoV infection, local IFN responses in the lungs were delayed relative to peak viral replication, which impeded virus clearance and was associated with the development of CRS19 . SARS-CoV-2 ORF3b is a potent interferon inhebitor and antagonist 20 The dysregulated IFN responses are indicative of the effective immunomodulatory strategies used by betacoronaviruses. During the incubation phase, SARS-CoV-2 replicates stealthily in host cells without detectably triggering IFNs, leading to high viral loads1. Coronaviruses are known to induce the formation of membranous compartments dedicated to viral RNA synthesis and thereby conceal viral pathogen-associated molecular patterns (PAMPs; for example, viral RNAs) from detection by host pattern recognition receptors (PRRs), such as RIG-I and MDA5. Furthermore, several conserved betacoronavirus proteins, predominantly non-structural proteins (nsps), are known to exert direct IFN-antagonistic activities. Some modify specific features of the viral RNA (by catalysing guanosine-N7 and ribose-2'-O methylation) to avoid recognition by specific PRRs (for example, nsp14 and nsp16), while others, such as nsp3 and nsp1, inhibit the signal transduction mediated by PRRs and by IFNAR, respectively19

--Impact of TLR3 on type I IFNs