Randomised Controlled Trial of Intravenous Nafamostat Mesylate in COVID pneumonitis: Phase 1b/2a Experimental Study to Investigate Safety, Pharmacokinetics and Pharmacodynamics
Authors: Quinn Tom M. , Gaughan Erin E. , Bruce Annya , Antonelli Jean , O’Connor Richard , Li Feng , McNamara Sarah , Koch Oliver , MacIntosh Claire , Dockrell David , Walsh Timothy , Blyth Kevin G. , Church Colin , Schwarze Jürgen , Boz Cecilia , Valanciute Asta , Burgess Matthew , Emanuel Philip , Mills Bethany , Rinaldi Giulia , Hardisty Gareth , Mills Ross , Findlay Emily , Jabbal Sunny , Duncan Andrew , Plant Sinéad , Marshall Adam D. L. , Young Irene , Russell Kay , Scholefield Emma , Nimmo Alastair F. , Nazarov Islom B. , Churchill Grant C. , McCullagh James S.O. , Ebrahimi Kourosh H. , Ferrett Colin , Templeton Kate , Rannard Steve , Owen Andrew , Moore Anne , Finlayson Keith , Shankar-Hari Manu , Norrie John , Parker Richard A. , Akram Ahsan R. , Anthony Daniel C. , Dear James W. , Hirani Nik , Dhaliwal Kevin 
Published: October 2021

Despite the success of vaccines and selected repurposed treatments, COVID-19 is likely to remain a global health problem and further chemotherapeutics are required. Many repurposed drugs have progressed rapidly to Phase 2 and 3 trials without characterisation of Pharmacokinetics (PK)/Pharmacodynamics (PD) including safety in COVID-19. One such drug is Nafamostat Mesylate (Nafamostat), a synthetic serine protease inhibitor with anticoagulant and anti-inflammatory properties. Preclinical data has demonstrated that it is has potent antiviral activity against SARS-CoV-2 by directly inhibiting the transmembrane protease serine 2 (TMPRSS2) dependent stage of host cell entry.

Methods

We present the findings of a phase Ib/II open label, platform randomised controlled trial (RCT), exploring the safety of intravenous Nafamostat in hospitalised patients with confirmed COVID-19 pneumonitis. Patients were assigned randomly to standard of care (SoC), Nafamostat or an alternative therapy. Secondary endpoints included clinical endpoints such as number of oxygen free days and clinical improvement/ deterioration, PK/PD, thromboelastometry, D Dimers, cytokines, immune cell flow cytometry and viral load.

Results

Data is reported from 42 patients, 21 of which were randomly assigned to receive intravenous Nafamostat. The Nafamostat group developed significantly higher plasma creatinine levels, more adverse events and a lower number of oxygen free days. There were no other statistically significant differences in the primary or secondary endpoints between Nafamostat and SoC. PK data demonstrated that intravenous Nafamostat was rapidly broken down to inactive metabolites. We observed an antifibrinolytic profile, and no significant anticoagulant effects in thromboelastometry. Participants in the Nafamostat group had higher D Dimers compared to SoC. There were no differences in cytokine profile and immune cell phenotype and viral loads between the groups.

Conclusion

In hospitalised patients with COVID-19, we did not observe evidence of anti-inflammatory, anticoagulant or antiviral activity with intravenous Nafamostat. Given the number of negative trials with repurposed drugs, our experimental medicine trial highlights the value of PK/PD studies prior to selecting drugs for efficacy trials. Given the mechanism of action, further evaluation of Nafamostat delivered via a different route may be warranted. This trial demonstrates the importance of experimental trials in new disease entities such as COVID-19 prior to selecting drugs for larger trials.