Nafamostat Mesylate in lipid carrier for nasal SARS-CoV2 titer reduction in a hamster model

Abstract

Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) has been responsible for the largest pandemic in recent decades. After seemingly being in control due to consequent lock-downs and social distancing, the majority of countries faces currently a second wave of exponentially increasing infections, hospital referrals and deaths due to SARS-CoV-2-mediated disease (COVID-19). To date, no effective vaccination has been found, and wearing masks and social distancing are the only effective approaches to reduce further spreading.However, unwillingness in the societies to distance again and consequently wear masks might be reasons for the second SARS-CoV-2 infection wave. User-friendly chemicals interfering at the host site with viral entry might be an approach to contain the pandemic. In addition, such an approach would work synergistic with vaccinations that miss new virus mutants.Nafamostat (NM) has been shown in vitro to interfere with cellular virus entry by inhibition of the host transmembrane protease serine 2 (TMPRSS2), an enzyme required for SARS-CoV-2 spike protein cleavage, a prerequisite for cell entry.We hypothesized that nasal application of NM in a liposomal layer (as additional mechanical barrier) could lower the nasal viral load and subsequently reduce the severity of COVID-19. We found, indeed, that nasal viral load one day post single NM application, was lowered in a hamster SARS-CoV-2 infection model. However, severity of subsequent local tissue destruction and weight loss due to pneumonitis was not favorably altered.In conclusion, a single NM application reduced nasal viral load, but did not favorably improve the outcome of COVID-19, likely due to the short half-time of NM. Improvement of NM stability or repetitive application (which was not permitted in this animal model according to Dutch law) might circumvent these challenges.

Evaluation of Nafamostat as Chemoprophylaxis for SARS-CoV-2 Infection in Hamsters

“…A single-dose pretreatment of Ad5- hACE2 -transduced mice and K18- hACE2 mice with 3 mg/kg of nafamostat intranasally delivered prior to inoculation with SARS-CoV-2 significantly reduced the viral titres over the study time course [ 26 ]. Furthermore, a study of 420 µg/mL of nafamostat suspended within a novel lipid formulation and administered intranasally to hamsters, which was immediately followed by inoculation with SARS-CoV-2, showed a transient but significant reduction in the viral load within the nasal cavity compared to controls [ 27 ]. Unfortunately, a histopathological assessment of the animals was not undertaken.…”

“…Unfortunately, a histopathological assessment of the animals was not undertaken. Also, it is not possible to ascertain whether the limited benefit was a result of the formulation itself, since unformulated nafamostat was not used as a control [ 27 ]. However, studies with a primary lung epithelium cell model demonstrated the low cytotoxicity of the lipid formulation up to 6 µg/mL of nafamostat, with evidence of SARS-CoV-2 inhibition at this dose [ 28 ].…”

A novel highly potent inhibitor of TMPRSS2-like proteases blocks SARS-CoV-2 variants of concern and is broadly protective against infection and mortality in mice

“…Plitidepsin is a promising HDA, which targets the ubiquitously expressed elongation factor 1-alpha and has demonstrated high potency (ED = 1.62 nM and SI = 40.4) against SARS-CoV-2 infection in pneumocyte-like cells 21 . Cm and nafamostat mesylate are also HDAs targeting serine proteases, including host TTSPs, that are undergoing human trials against SARS-CoV-2; however, no significant protection against infection was observed in the adenovirus hACE2 model (Cm) or hamster model (nafamostat mesylate) of SARS-CoV-2 infection 4,51,52 . Recently reported clinical trial data for Cm treatment of hospitalized COVID-19 patients demonstrated a lack of impact on time to recovery and incidence of death following SARS-CoV-2 infection 19 .…”

Evaluation of intranasal nafamostat or camostat for SARS-CoV-2 chemoprophylaxis in Syrian golden hamsters

“…However, no impact on pathology was reported. 25 It is not currently possible to ascertain whether the limited benefit were a result of the formulation itself since unformulated nafamostat was not used as a control in the published study. However, studies in a primary lung epithelium cell model did demonstrate low cytotoxicity of the lipid formulation up to 6 µg/mL nafamostat and evidence of SARS-CoV-2 inhibition at this dose.…”