A Randomized Trial of Nafamostat for Covid-19

TMPRSS2 inhibitors for the treatment of COVID-19 in adults: a systematic review and meta-analysis of randomized clinical trials of nafamostat and camostat mesylate

BACKGROUND

Synthetic serine protease inhibitors block the cellular enzyme transmembrane protease serine 2, thus preventing SARS-CoV-2 cell entry. There are two relevant drugs in this class, namely, nafamostat (intravenous formulation) and camostat (oral formulation).

OBJECTIVE

To determine whether transmembrane protease serine 2 inhibition with nafamostat or camostat is associated with a reduced risk of 30-day all-cause mortality in adults with COVID-19.

DATA SOURCES

Scientific databases and clinical trial registry platforms.

STUDY ELIGIBILITY CRITERIA, INTERVENTIONS, AND PARTICIPANTS

Preprints or published randomized clinical trials (RCTs) of nafamostat or camostat vs. usual care or placebo in adults requiring treatment for COVID-19.

METHODS OF DATA SYNTHESIS AND RISK-OF-BIAS ASSESSMENT

The primary outcome of the meta-analysis was 30-day all-cause mortality. Secondary outcomes included time to recovery, adverse events, and serious adverse events. Risk of bias (RoB) was assessed using the revised Cochrane RoB 2 tool for individually randomized trials. Meta-analysis was conducted in the R package meta (v7.0-0) using inverse variance and random effects. Protocol registration number was INPLASY202320120.

RESULTS

Twelve RCTs were included. Overall, the number of available patients was small (nafamostat = 387; camostat = 1061), the number of enrolled patients meeting the primary outcome was low (nafamostat = 12; camostat = 13), and heterogeneity was high. In hospitalized adults, we did not identify differences in 30-day all-cause mortality (risk ratio [95% CI]: 0.58 [0.19, 1.80], p 0.34; I2 = 0%; n = 6) and time to recovery (mean difference [95% CI]: 0.08 days [-0.74, 0.89], p 0.86; n = 2) between nafamostat vs. usual care; and for 30-day all-cause mortality (risk ratio [95% CI]: 0.99 [0.31, 3.18], p 0.99; n = 2) between camostat vs. placebo.

CONCLUSION

The RCT evidence is inconclusive to determine whether there is a mortality reduction and safety with either nafamostat or camostat for the treatment of adults with COVID-19. There were high RoB, small sample size, and high heterogeneity between RCTs.

Host Receptor Targeting to Treat Covid-19

Not long after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified as the cause of coronavirus disease 2019 (Covid-19), in vitro experiments revealed that SARS-CoV-2 infection of human cells depended on the binding of the viral spike protein to the human cell-surface receptor angiotensin-converting enzyme 2 (ACE-2).1 Additional experiments demonstrated that infection could be blocked by inhibiting transmembrane protease, serine 2 (TMPRSS2), which is a host enzyme that cleaves the viral spike protein after binding to ACE-2 and facilitates entry of the virus into the host cell.

Prior Ground: Selection of Prior Distributions When Analyzing Clinical Trial Data Using Bayesian Methods

Increasingly, investigators are choosing to use Bayesian methods for the analysis of clinical trial data. Unlike classical statistical methods that treat model parameter values (such as treatment effects) as fixed, Bayesian methods view parameters as following a probability distribution. As we have written previously,1 by analyzing clinical trial data using Bayesian methods one can obtain quantities that may be of interest to clinicians, providers, and patients, such as the probability that a treatment effect is more or less than 0, that is, the probability that a treatment is effective.