Search

Objectives: This study aimed to assess the efficacy and safety of 300 mg camostat mesylate three times daily in a fasted state to treat early phase COVID-19 in an ambulatory setting. Methods: We conducted a phase II randomized controlled trial in symptomatic (maximum 5 days) and asymptomatic patients with confirmed COVID-19 infection. Patients were randomly assigned in a 2:1 ratio to receive either camostat mesylate or a placebo. Outcomes included change in nasopharyngeal viral load, time to clinical improvement, the presence of neutralizing antibodies, and safety. Results: Of 96 participants randomized between November 2020 and June 2021, analyses were performed on the data of 90 participants who completed treatment (N = 61 camostat mesylate, N = 29 placebo). The estimated mean change in cycle threshold between day 1 and day 5 between the camostat and placebo group was 1.183 (P = 0.511). The unadjusted hazard ratio for clinical improvement in the camostat group was 0.965 (95% confidence interval, 0.480-1.942, P = 0.921 by Cox regression). The percentage distribution of the 50% neutralizing antibody titer at day 28 visit and frequency of adverse events were similar between the two groups. Conclusion: Under this protocol, camostat mesylate was not found to be effective as an antiviral drug against SARS-CoV-2.Trial registration: ClinicalTrials.gov NCT04625114; November 12, 2020.

The search for potent oral drugs either through synthetic routes or by drug repurposing for combating the dreaded covid-19 virus is still ongoing. The coronavirus spike glycoprotein and several other non-structural proteins play crucial roles in the replication and transmission of this virus. Recent research have identified ivermectin, nafamostat, and camostat as promising drug inhibitors of SARS-CoV-2 target proteins. The broad-spectrum inhibitory action of ivermectin, nafamostat, and camostat on the spike glycoprotein and some non-structural proteins of this virus was studied in silico. The spike glycoprotein, nsp3, nsp5, nsp9, nsp10, nsp13, and nsp16 were selected for this study and were downloaded from the protein data bank. Flexible docking procedure implemented in Auto Dock Vina module was deployed for the docking procedure of the drugs with the protein receptors. Although ivermectin had the best inhibitory action on the viral spike protein and nsp10, nafamostat was identified as the compound with the best broad-spectrum activity on this virus, having the highest binding affinity values of – 9.4kcal/mol, – 7.9 Kcal/mol, – 6.1 Kcal/mol, – 8.0 Kcal/mol, and – 8.7 Kcal/mol for nsp3, nsp5, nsp9, nsp13, and nsp16 respectively. This drug, in combination with ivermectin could therefore be explored further as potential compounds that could be modified to curb the menace of the covid-19 pandemic.

The global coronavirus pandemic has burdened the human population with mass fatalities and disastrous socio-economic consequences. The frequent occurrence of these new variants has fueled the already prevailing challenge. There is still a necessity for highly effective small molecular agents to prevent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Here, we targeted the human transmembrane surface protease TMPRSS2, which is essential for proteolytic activation of SARS-CoV-2. Camostat is a well-known inhibitor of serine proteases and an effective TMPRSS2 inhibitor. A virtual library of camostat-like compounds was computationally screened against the catalytic site of TMPRSS2. Following a sequential in-depth molecular docking and dynamics simulation, we report the compounds that exhibited promising efficacy against TMPRSS2. The molecular docking and MM/PBSA free energy calculation study indicates these compounds carry excellent binding affinity against TMPRSS2 and found them more effective than camostat. The study will open doors for the effective treatment of coronavirus disease 2019.

Summary: Background: The effectiveness of combination therapy for COVID-19 pneumonia remains unclear. We evaluated favipiravir, camostat, and ciclesonide combination therapy in patients with moderate COVID-19 pneumonia. Methods: In this open-label phase 3 study, hospitalized adults who were positive for SARS-CoV-2 and had COVID-19 pneumonia were enrolled prior to official vaccination drive in Japan. Participants were randomly assigned to favipiravir monotherapy or favipiravir + camostat + ciclesonide combination therapy. The primary outcome was the length of hospitalization due to COVID-19 infection after study treatment. The hospitalization period was calculated from the time of admission to the time of patient discharge using the clinical management guide of COVID-19 for front-line healthcare workers developed by the Japanese Ministry of Health, Labour, and Welfare (Version 3). Cases were registered between November 11, 2020, and May 31, 2021. Japan Registry of Clinical Trials registration: jRCTs031200196. Findings: Of 121 enrolled patients, 56 received monotherapy and 61 received combination therapy. Baseline characteristics were balanced between the groups. The median time of hospitalization was 10 days for the combination and 11 days for the monotherapy group. The median time to discharge was statistically significantly lower in the combination therapy vs monotherapy group (HR, 1·67 (95% CI 1·03–2·7; P = 0·035). The hospital discharge rate was statistically significantly higher in the combination therapy vs monotherapy group in patients with less severe COVID-19 infections and those who were ≤60 years. There were no significant differences in clinical findings between the groups at 4, 8, 11, 15, and 29 days. Adverse events were comparable between the groups. There were two deaths, with one in each group. Interpretation: Combination oral favipiravir, camostat and, ciclesonide therapy could decrease the length of hospitalization stays without safety concerns in patients with moderate COVID-19 pneumonia. However, lack of hard clinical primary outcome is one of the major limitations of the study. Funding: This research was supported by Japan Agency for Medical Research and Development (AMED) under Grant Number 20fk0108261h0001.

Abstract Objectives The primary objective is to evaluate the efficacy of camostat to prevent respiratory deterioration in patients with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. Secondary objectives include assessment of the ability of camostat to reduce the requirement for Coronavirus disease 2019 (COVID-19) related hospital admission and to reduce the requirement for supplementary oxygen and ventilation as treatment for SARS-CoV-2 infection, to evaluate overall mortality related to COVID-19 and to evaluate the efficacy of camostat by effect on clinical improvement. Research objectives include to assess change in COVID-19 symptom severity, to evaluate the ability of camostat to reduce viral load throughout duration of illness as well as translational research on host and viral genomics, serum antibody production, COVID-19 diagnostics, and validation of laboratory testing methods and biomarkers. Trial design SPIKE-1 is a randomised, multicentre, prospective, open label, community-based clinical trial. Eligible patients will be randomised 1:1 to the camostat treatment arm and control arm (best supportive care). The trial is designed to include a pilot phase recruiting up to 50 patients in each arm. An initial review at the end of the pilot phase will allow assessment of available data and inform the requirement for any protocol adaptations to include refinement of eligibility criteria to enrich the patient population and sample size calculations. Up to 289 additional patients will be randomised in the continuation phase of the trial. A formal interim analysis will be performed once 50% of the maximum sample size has been recruited Participants The trial will recruit adults (≥ 18 years) who score moderate to very high risk according to COVID-age risk calculation, with typical symptoms of COVID-19 infection as per Public Health England guidance or equivalent organisations in the UK, Health Protection Scotland, Public Health Wales, Public Health Agency (Northern Ireland) and with evidence of current COVID-19 infection from a validated assay. The trial is being conducted in the UK and patients are recruited through primary care and hospital settings. Intervention and comparator Eligible patients with be randomised to receive either camostat tablets, 200 mg four times daily (qds) for 14 days (treatment arm) or best supportive care (control arm). Main outcomes Primary outcome measure: the rate of hospital admissions requiring supplemental oxygen. Secondary outcome measures include: the rate of COVID-19 related hospital admission in patients with SARS-CoV-2 infection; the number of supplementary oxygen-free days and ventilator-free days measured at 28 days from randomisation; the rate of mortality related to COVID-19 one year from randomisation; the time to worst point on the nine-point category ordinal scale (recommended by the World Health Organization: Coronavirus disease (COVID-2019)) or deterioration of two points or more, within 28 days from randomisation. Research outcomes include the assessment of change in COVID-19 symptom severity on days 1-14 as measured by (1) time to apyrexia (maintained for 48 hrs) by daily self-assessment of temperature, time to improvement (by two points) in peripheral oxygenation saturation defined by daily self-assessment of fingertip peripheral oxygenation saturation levels, (3) assessment of COVID-19 symptoms using the Flu-iiQ questionnaire (determined by app recording and/or daily video call (or phone) consultation and (4) assessment of functional score (where possible) at screening, day 7 and 14. The ability of camostat to reduce viral load throughout duration of illness will be assessed by (1) change in respiratory (oropharyngeal/nasopharyngeal swab RT-PCR) log10 viral load from baseline to Days 7 and 14, (2) change in respiratory (saliva RT-PCR) log10 viral load from baseline to Days 1-14 and (3) change in upper respiratory viral shedding at Day 1 -14 measured as time to clearance of nasal SARS-CoV-2, defined as 2 consecutive negative swabs by qPCR. Additional translational research outcomes include assessment of host and viral genomics, serum antibody production and COVID-19 diagnostics at baseline and on Days 7 and 14. Randomisation Eligible patients will be randomised using an interactive web response system (IWRS) in a 1:1 ratio to one of two arms: (1) treatment arm or (2) control arm. Blinding (masking) The trial is open-label. Numbers to be randomised (sample size) The trial is designed to include a pilot and a continuation phase. Up to 100 patients (randomised 1:1 treatment and control arm) will be recruited in the pilot phase and a maximum of 289 patients (randomised 1:1 treatment and control) will be recruited as part of the continuation phase. The total number of patients recruited will not exceed 389. Trial Status Protocol version number v3 25 September 2020. Trial opened to recruitment on 04 August 2020. The authors anticipate recruitment to be completed by October 2021. Trial registration EudraCT 2020-002110-41; 18 June 2020 ClinicalTrials.gov NCT04455815 ; 02 July 2020 Full protocol The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). Unpublished PK data provided under confidentiality agreement to the trial Sponsor has been removed from the background section of the protocol to allow for publication of the trial protocol. In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

ABSTRACT The SARS-CoV-2 coronavirus, which causes COVID-19, uses a viral surface spike protein for host cell entry and the human cell-surface transmembrane serine protease, TMPRSS2, to process the spike protein. Camostat mesylate, an orally available and clinically used serine protease inhibitor, inhibits TMPRSS2, supporting clinical trials to investigate its use in COVID-19. A one-compartment pharmacokinetic (PK)/pharmacodynamic (PD) model for camostat and the active metabolite FOY-251 was developed, incorporating TMPRSS2 reversible covalent inhibition by FOY-251, and empirical equations linking TMPRSS2 inhibition of SARS-CoV-2 cell entry. The model predicts that 95% inhibition of TMPRSS2 is required for 50% inhibition of viral entry efficiency. For camostat 200 mg dosed four times daily, 90% inhibition of TMPRSS2 is predicted to occur but with only about 40% viral entry inhibition. For 3-fold higher camostat dosing, marginal improvement of viral entry rate inhibition, up to 54%, is predicted. Because respiratory tract viral load may be associated with negative outcome, even modestly reducing viral entry and respiratory tract viral load may reduce disease progression. This modeling also supports medicinal chemistry approaches to enhancing PK/PD and potency of the camostat molecule. IMPORTANCE Strategies to repurpose already-approved drugs for the treatment of COVID-19 has been attractive since the beginning of the pandemic. Camostat mesylate, a serine protease inhibitor approved in Japan for the treatment of acute exacerbations of chronic pancreatitis, inhibits TMPRSS1, a host cell surface serine protease essential for SARS-CoV-2 viral entry. In vitro experiments provided data suggesting that camostat might be effective in the treatment of COVID-19. Multiple clinical trials were planned to test the hypothesis that camostat would be beneficial for treating COVID-19 (for example, clinicaltrials.gov, NCT04353284). The present work used a one-compartment pharmacokinetic (PK)/pharmacodynamic (PD) mathematical model for camostat and the active metabolite FOY-251, incorporating TMPRSS2 reversible covalent inhibition by FOY-251, and empirical equations linking TMPRSS2 inhibition of SARS-CoV-2 cell entry. This work is valuable to guide further development of camostat mesylate and possible medicinal chemistry derivatives for the treatment of COVID-19.

ABSTRACT The coronavirus disease 2019 (COVID-19) pandemic has caused significant morbidity and mortality on a global scale. The etiologic agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), initiates host cell entry when its spike protein (S) binds to its receptor, angiotensin-converting enzyme 2 (ACE2). In airway epithelia, the spike protein is cleaved by the cell surface protease TMPRSS2, facilitating membrane fusion and entry at the cell surface. This dependence on TMPRSS2 and related proteases suggests that protease inhibitors might limit SARS-CoV-2 infection in the respiratory tract. Here, we tested two serine protease inhibitors, camostat mesylate and nafamostat mesylate, for their ability to inhibit entry of SARS-CoV-2 and that of a second pathogenic coronavirus, Middle East respiratory syndrome coronavirus (MERS-CoV). Both camostat and nafamostat reduced infection in primary human airway epithelia and in the Calu-3 2B4 cell line, with nafamostat exhibiting greater potency. We then assessed whether nafamostat was protective against SARS-CoV-2 in vivo using two mouse models. In mice sensitized to SARS-CoV-2 infection by transduction with human ACE2, intranasal nafamostat treatment prior to or shortly after SARS-CoV-2 infection significantly reduced weight loss and lung tissue titers. Similarly, prophylactic intranasal treatment with nafamostat reduced weight loss, viral burden, and mortality in K18-hACE2 transgenic mice. These findings establish nafamostat as a candidate for the prevention or treatment of SARS-CoV-2 infection and disease pathogenesis. IMPORTANCE The causative agent of COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), requires host cell surface proteases for membrane fusion and entry into airway epithelia. We tested the hypothesis that inhibitors of these proteases, the serine protease inhibitors camostat and nafamostat, block infection by SARS-CoV-2. We found that both camostat and nafamostat reduce infection in human airway epithelia, with nafamostat showing greater potency. We then asked whether nafamostat protects mice against SARS-CoV-2 infection and subsequent COVID-19 lung disease. We performed infections in mice made susceptible to SARS-CoV-2 infection by introducing the human version of ACE2, the SARS-CoV-2 receptor, into their airway epithelia. We observed that pretreating these mice with nafamostat prior to SARS-CoV-2 infection resulted in better outcomes, in the form of less virus-induced weight loss, viral replication, and mortality than that observed in the untreated control mice. These results provide preclinical evidence for the efficacy of nafamostat in treating and/or preventing COVID-19.

Abstract Background Chronic pancreatitis (CP) is a progressive, fibro-inflammatory disease characterized by enzymatic autoactivation and subsequent fibrotic replacement of acinar cells. A significant proportion of patients develop pain, which may be due to many causes, including perineural inflammation, altered central processing of pain signals, parenchymal structural changes, and ductal obstruction. Currently there are no approved medical treatment options for CP-associated pain. NI-03 (camostat mesilate) is an orally administered serine protease inhibitor that reduces pancreatic enzyme activity and has been widely used for the treatment of CP-associated pain in Japan. The current study will assess the safety and efficacy of NI-03 for reduction of CP-associated pain in the USA. Methods The current study consists of two phases. First, a phase I study will be performed to establish the pharmacokinetics and safety profile over a 1-week period following a single dose (100, 200, or 300 mg). Subsequently, a phase II study will be performed consisting of a double-blind, randomized, controlled trial (RCT). This RCT will evaluate the efficacy of each of the three doses of NI-03 given three times daily compared to placebo over 28 days. A 7-day, single-blind, run-in period will precede the double-blind phase to assess baseline pain characteristics. The primary efficacy outcome is the average of worst daily pain scores (numeric rating scale of 0–10) over the terminal 7 days of the study period compared to baseline. Secondary efficacy outcomes include change in opioid dose and quality of life measures, and time to first rescue intravenous analgesic. Adverse events will be recorded. Discussion NI-03 has been used successfully and safely in Japan to treat CP-associated pain. The aim of the current study is to assess the safety and efficacy of NI-03 using a rigorous RCT in a population in the USA. This study may fill an important clinical gap to provide an effective medical treatment option for CP-associated pain. Trial registration ClinicalTrials.gov, NCT02693093. Registered through the National Institutes of Health on 26 February 2016.

Coronavirus disease 2019 (COVID-19) can lead to multi-organ failure influenced by comorbidities and age. Binding of the severe acute respiratory syndrome coronavirus 2 spike protein (SARS-CoV-2 S protein) to angiotensin-converting enzyme 2 (ACE2), along with proteolytic digestion of the S protein by furin and transmembrane protease serine subtype 2 (TMPRSS2), provokes internalization of SARS-CoV-2 into the host cell. Productive infection occurs through viral replication in the cytosol and cell-to-cell transmission. The catalytic activity of TMPRSS2 can be blocked by the trypsin-like serine protease inhibitor camostat, which impairs infection by SARS-CoV-2. At the site of infection, immune cells, such as neutrophils, infiltrate and become activated, releasing neutrophil serine proteases (NSPs), including cathepsin G (CatG), neutrophil elastase (NE), and proteinase 3 (PR3), which promote the mounting of a robust immune response. However, NSPs might be involved in infection and the severe outcome of COVID-19 since the uncontrolled proteolytic activity is responsible for many complications, including autoimmunity, chronic inflammatory disorders, cardiovascular diseases, and thrombosis. Here, we demonstrate that camostat does not inhibit the catalytic activity of CatG, NE, and PR3, indicating the need for additional selective serine protease inhibitors to reduce the risk of developing severe COVID-19.

Inhibition of transmembrane serine protease 2 (TMPRSS2) is expected to block the spike protein-mediated fusion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nafamostat, a potent TMPRSS2 inhibitor as well as a candidate for anti-SARS-CoV-2 drug, possesses the same acyl substructure as camostat, but is known to have a greater antiviral effect. A unique aspect of the molecular binding of nafamostat has been recently reported to be the formation of a covalent bond between its acyl substructure and Ser441 in TMPRSS2. In this study, we investigated crucial elements that cause the difference in anti-SARS-CoV-2 activity of nafamostat and camostat. In silico analysis showed that Asp435 significantly contributes to the binding of nafamostat and camostat to TMPRSS2, while Glu299 interacts strongly only with nafamostat. The estimated binding affinity for each compound with TMPRSS2 was actually consistent with the higher activity of nafamostat; however, the evaluation of the newly synthesized nafamostat derivatives revealed that the predicted binding affinity did not correlate with their anti-SARS-CoV-2 activity measured by the cytopathic effect (CPE) inhibition assay. It was further shown that the substitution of the ester bond with amide bond in nafamostat resulted in significantly weakened anti-SARS-CoV-2 activity. These results strongly indicate that the ease of covalent bond formation with Ser441 in TMPRSS2 possibly plays a major role in the anti-SARS-CoV-2 effect of nafamostat and its derivatives.