Comparison of gabexate mesilate and nafamostat mesilate for disseminated intravascular coagulation associated with hematological malignancies

Clinical practice guidelines for management of disseminated intravascular coagulation in Japan 2024. Part 2: hematologic malignancy

Disseminated intravascular coagulation (DIC) associated with hematologic malignancies, particularly acute promyelocytic leukemia (APL), is characterized by marked fibrinolytic activation, which leads to severe bleeding complications. Therefore, appropriate diagnosis and management of DIC are crucial for preventing bleeding-related mortality. However, to date, no clinical guidelines have specifically addressed hematologic malignancy-associated DIC. Therefore, we developed diagnostic and management algorithms for DIC based on a systematic literature review. Notably, these guidelines recommend using the JSTH DIC diagnostic criteria (2017 version) or the former Ministry of Health and Welfare DIC diagnostic criteria (1983 version) to diagnose DIC. Furthermore, in the management of DIC, it is essential to treat the underlying disease through transfusion of platelet concentrates and fresh frozen plasma, if necessary. A systematic review of antifibrinolytic and anticoagulant therapies concluded that tranexamic acid therapy is not strongly recommended for patients with APL undergoing treatment with all-trans retinoic acid (Grade 1C). The use of recombinant thrombomodulin is weakly recommended (Grade 2B), whereas the use of other anticoagulants, including heparin and serine protease inhibitors, is weakly not recommended (Grade 2C). Therefore, we hope that these guidelines will help physicians find the best possible solutions in clinical practice.

Characteristics of Bleeding Complications in Patients with Severe COVID-19 Requiring Veno-venous Extracorporeal Membrane Oxygenation in Japan

Complications during veno-venous extracorporeal membrane oxygenation (VV-ECMO) are associated with in-hospital mortality. Asian patients on extracorporeal membrane oxygenation (ECMO) have higher risks of bleeding and in-hospital mortality than Caucasian patients. This study aimed to characterize and identify bleeding complications and their associated factors related to in-hospital mortality in patients with severe coronavirus disease 2019 (COVID-19) requiring VV-ECMO in Japan.In this retrospective observational analysis, the prospective nationwide multicenter registry was used to track real-time information from intensive care units throughout Japan during the COVID-19 pandemic. VV-ECMO patients' registry data between February 1, 2020 and October 31, 2022 were used.This study included 441 patients; 178 (40%) had bleeding complications in the following sites: 20% at the cannulation site, 16% in the gastrointestinal tract, 16% in the ear-nose-throat, 13% at the tracheostomy site, 9% intrathoracic, 6% intracranial, and 5% in the iliopsoas. Anticoagulation was discontinued in >50% of patients with intracranial, iliopsoas, and gastrointestinal tract bleeding. ECMO was discontinued in one-third of patients with intracranial, intramuscular, and iliopsoas hemorrhages. Multivariable logistic regression analysis revealed that only gastrointestinal tract bleeding was associated with in-hospital mortality (odds ratio: 2.49; 95% confidence interval: 1.11-5.60; p = 0.03).Incidence of bleeding complications was 40% in the Japanese population. Gastrointestinal tract bleeding emerged as a significant predictor of adverse outcomes, necessitating further research into preventive strategies and optimized care protocols. These findings can guide the management of VV-ECMO patients with COVID-19.

Endothelial Glycocalyx in the Peripheral Capillaries is Injured Under Oxaliplatin-Induced Neuropathy

Oxaliplatin, a platinum-based anticancer drug, is associated with peripheral neuropathy (oxaliplatin-induced peripheral neuropathy, OIPN), which can lead to worsening of quality of life and treatment interruption. The endothelial glycocalyx, a fragile carbohydrate-rich layer covering the luminal surface of endothelial cells, acts as an endothelial gatekeeper and has been suggested to protect nerves, astrocytes, and other cells from toxins and substances released from the capillary vessels. Mechanisms underlying OIPN and the role of the glycocalyx remain unclear. This study aimed to define changes in the three-dimensional ultrastructure of capillary endothelial glycocalyx near nerve fibers in the hind paws of mice with OIPN. The mouse model of OPIN revealed disruption of the endothelial glycocalyx in the peripheral nerve compartment, accompanied by vascular permeability, edema, and damage to the peripheral nerves. To investigate the potential treatment interventions, nafamostat mesilate, a glycocalyx protective agent was used in tumor-bearing male mice. Nafamostat mesilate suppressed mechanical allodynia associated with neuropathy. It also prevented intra-epidermal nerve fiber loss and improved vascular permeability in the peripheral paws. The disruption of endothelial glycocalyx in the capillaries that lie within peripheral nerve bundles is a novel finding in OPIN. Furthermore, these findings point toward the potential of a new treatment strategy targeting endothelial glycocalyx to prevent vascular injury as an effective treatment of neuropathy as well as of many other diseases. PERSPECTIVE: OIPN damages the endothelial glycocalyx in the peripheral capillaries, increasing vascular permeability. In order to prevent OIPN, this work offers a novel therapy approach that targets endothelial glycocalyx.

A systematic review and meta-analysis of recombinant human soluble thrombomodulin for the treatment of DIC associated with hematological malignancies

BACKGROUND

Recombinant human soluble thrombomodulin (rhTM) is commonly used in Japan to treat disseminated intravascular coagulation (DIC), but its efficacy compared with other anticoagulants is unclear. We conducted a systematic review and meta-analysis to investigate this issue in DIC patients with hematological malignancies.

METHODS

We searched PubMed, Cochrane, and Scopus for prospective and retrospective studies evaluating the efficacy and safety of rhTM in DIC patients with hematological malignancies between April 2008 and April 2023. We performed a systematic review and meta-analysis evaluating recovery from DIC, hemorrhagic adverse events (AEs), and overall survival (OS).

RESULTS

We analyzed one prospective (64 patients) and seven retrospective studies (209 patients). Use of rhTM was associated with a higher rate of recovery from DIC (OR: 2.25 [1.09-4.63] and 1.98 [1.12-3.50] in prospective and retrospective studies, respectively; same order below) and fewer hemorrhagic AEs (OR: 0.83 [0.30-2.30] and 0.21 [0.08-0.57]). rhTM did not improve OS (OR: 1.06 [0.42-2.66] and 1.72 [0.87-3.39]), although the incidence of hemorrhagic death was lower in the rhTM group (0 of 94 patients).

CONCLUSION

Use of rhTM in patients with hematological malignancy-associated DIC is strongly expected to be effective and safe.

Drug repurposing for the treatment of COVID-19: Targeting nafamostat to the lungs by a liposomal delivery system

Despite tremendous global efforts since the beginning of the COVID-19 pandemic, still only a limited number of prophylactic and therapeutic options are available. Although vaccination is the most effective measure in preventing morbidity and mortality, there is a need for safe and effective post-infection treatment medication. In this study, we explored a pipeline of 21 potential candidates, examined in the Calu-3 cell line for their antiviral efficacy, for drug repurposing. Ralimetinib and nafamostat, clinically used drugs, have emerged as attractive candidates. Due to the inherent limitations of the selected drugs, we formulated targeted liposomes suitable for both systemic and intranasal administration. Non-targeted and targeted nafamostat liposomes (LipNaf) decorated with an Apolipoprotein B peptide (ApoB-P) as a specific lung-targeting ligand were successfully developed. The developed liposomal formulations of nafamostat were found to possess favorable physicochemical properties including nano size (119-147 nm), long-term stability of the normally rapidly degrading compound in aqueous solution, negligible leakage from the liposomes upon storage, and a neutral surface charge with low polydispersity index (PDI). Both nafamostat and ralimetinib liposomes showed good cellular uptake and lack of cytotoxicity, and non-targeted LipNaf demonstrated enhanced accumulation in the lungs following intranasal (IN) administration in non-infected mice. LipNaf retained its anti-SARS-CoV 2 activity in Calu 3 cells with only a modest decrease, exhibiting complete inhibition at concentrations >100 nM. IN, but not intraperitoneal (IP) treatment with targeted LipNaf resulted in a trend to reduced viral load in the lungs of K18-hACE2 mice compared to targeted empty Lip. Nevertheless, upon removal of outlier data, a statistically significant 1.9-fold reduction in viral load was achieved. This observation further highlights the importance of a targeted delivery into the respiratory tract. In summary, we were able to demonstrate a proof-of-concept of drug repurposing by liposomal formulations with anti-SARS-CoV-2 activity. The biodistribution and bioactivity studies with LipNaf suggest an IN or inhalation route of administration for optimal therapeutic efficacy.

RAndomized Clinical Trial Of NAfamostat Mesylate, A Potent Transmembrane Protease Serine 2 (TMPRSS2) Inhibitor, in Patients with COVID-19 Pneumonia

Even though SARS-CoV-2 was declared by WHO as constituting no longer a public health emergency, the development of effective treatments against SARS-CoV-2 infection remains a critical issue to prevent complications, particularly in fragile patients. The protease inhibitor nafamostat, currently used in Japan and Korea for pancreatitis, owing to its anticoagulant properties for disseminated intravascular coagulation (DIC), is appealing for the treatment of COVID-19 infection, because it potently inhibits the transmembrane protease serine 2 (TMPRSS2) that, after virus binding to ACE-2, allows virus entry into the cells and replication. Moreover, it could prevent the DIC and pulmonary embolism frequently associated with COVID-19 infection. The goal of the RAndomized Clinical Trial Of NAfamostat (RACONA) study, designed as a prospective randomized, double-blind placebo-controlled clinical trial, was to investigate the efficacy and safety of nafamostat mesylate (0.10 mg/kg/h iv for 7 days), on top of the optimal treatment, in COVID-19 hospitalized patients. We could screen 131 patients, but due to the predefined strict inclusion and exclusion criteria, only 15 could be randomized to group 1 (n = 7) or group 2 (n = 8). The results of an ad interim safety analysis showed similar overall trends for variables evaluating renal function, coagulation, and inflammation. No adverse events, including hyperkalemia, were found to be associated with nafamostat. Thus, the RACONA study showed a good safety profile of nafamostat, suggesting that it could be usefully used in COVID-19 hospitalized patients.

A Tale of Two Proteases: MPro and TMPRSS2 as Targets for COVID-19 Therapies

Considering the importance of the 2019 outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) resulting in the coronavirus disease 2019 (COVID-19) pandemic, an overview of two proteases that play an important role in the infection by SARS-CoV-2, the main protease of SARS-CoV-2 (MPro) and the host transmembrane protease serine 2 (TMPRSS2), is presented in this review. After summarising the viral replication cycle to identify the relevance of these proteases, the therapeutic agents already approved are presented. Then, this review discusses some of the most recently reported inhibitors first for the viral MPro and next for the host TMPRSS2 explaining the mechanism of action of each protease. Afterward, some computational approaches to design novel MPro and TMPRSS2 inhibitors are presented, also describing the corresponding crystallographic structures reported so far. Finally, a brief discussion on a few reports found some dual-action inhibitors for both proteases is given. This review provides an overview of two proteases of different origins (viral and human host) that have become important targets for the development of antiviral agents to treat COVID-19.

Nafamostat Mesylate for Treatment of COVID-19 in Hospitalised Patients: A Structured, Narrative Review

The search for clinically effective antivirals against the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is ongoing. Repurposing of drugs licensed for non-coronavirus disease 2019 (COVID-19) indications has been extensively investigated in laboratory models and in clinical studies with mixed results. Nafamostat mesylate (nafamostat) is a drug licensed in Japan and Korea for indications including acute pancreatitis and disseminated intravascular coagulation. It is available only for continuous intravenous infusion. In vitro human lung cell line studies with nafamostat demonstrate high antiviral potency against SARS-CoV-2 (half maximal inhibitory concentration [IC50] of 0.0022 µM [compared to remdesivir 1.3 µM]), ostensibly via inhibition of the cellular enzyme transmembrane protease serine 2 (TMPRSS2) preventing viral entry into human cells. In addition, the established antithrombotic activity is hypothesised to be advantageous given thrombosis-associated sequelae of COVID-19. Clinical reports to date are limited, but indicate a potential benefit of nafamostat in patients with moderate to severe COVID-19. In this review, we will explore the pre-clinical, pharmacokinetic and clinical outcome data presently available for nafamostat as a treatment for COVID-19. The recruitment to ongoing clinical trials is a priority to provide more robust data on the safety and efficacy of nafamostat as a treatment for COVID-19.

Nafamostat is a Potent Human Diamine Oxidase Inhibitor Possibly Augmenting Hypersensitivity Reactions during Nafamostat Administration

Nafamostat is an approved short-acting serine protease inhibitor. However, its administration is also associated with anaphylactic reactions. One mechanism to augment hypersensitivity reactions could be inhibition of diamine oxidase (DAO). The chemical structure of nafamostat is related to the potent DAO inhibitors pentamidine and diminazene. Therefore, we tested whether nafamostat is a human DAO inhibitor. Using different activity assays, nafamostat reversibly inhibited recombinant human DAO with an IC50 of 300-400 nM using 200 µM substrate concentrations. The Ki of nafamostat for the inhibition of putrescine and histamine deamination is 27 nM and 138 nM, respectively For both substrates, nafamostat is a mixed mode inhibitor with P values of <0.01 compared with other inhibition types. Using 80-90% EDTA plasma, the IC50 of nafamostat inhibition was approximately 360 nM using 20 µM cadaverine. In 90% EDTA plasma, the IC50 concentrations were 2-3 µM using 0.9 µM and 0.18 µM histamine as substrate. In silico modeling showed a high overlap compared with published diminazene crystallography data, with a preferred orientation of the guanidine group toward topaquinone. In conclusion, nafamostat is a potent human DAO inhibitor and might increase severity of anaphylactic reaction by interfering with DAO-mediated extracellular histamine degradation. SIGNIFICANCE STATEMENT: Treatment with the short-acting anticoagulant nafamostat during hemodialysis, leukocytapheresis, extracorporeal membrane oxygenator procedures, and disseminated intravascular coagulation is associated with severe anaphylaxis in humans. Histamine is a central mediator in anaphylaxis. Potent inhibition of the only extracellularly histamine-degrading enzyme diamine oxidase could augment anaphylaxis reactions during nafamostat treatment.

Therapeutic Strategies for Disseminated Intravascular Coagulation Associated with Aortic Aneurysm

Aortic aneurysms are sometimes associated with enhanced-fibrinolytic-type disseminated intravascular coagulation (DIC). In enhanced-fibrinolytic-type DIC, both coagulation and fibrinolysis are markedly activated. Typical cases show decreased platelet counts and fibrinogen levels, increased concentrations of fibrin/fibrinogen degradation products (FDP) and D-dimer, and increased FDP/D-dimer ratios. Thrombin-antithrombin complex or prothrombin fragment 1 + 2, as markers of coagulation activation, and plasmin-α₂ plasmin inhibitor complex, a marker of fibrinolytic activation, are all markedly increased. Prolongation of prothrombin time (PT) is not so obvious, and the activated partial thromboplastin time (APTT) is rather shortened in some cases. As a result, DIC can be neither diagnosed nor excluded based on PT and APTT alone. Many of the factors involved in coagulation and fibrinolysis activation are serine proteases. Treatment of enhanced-fibrinolytic-type DIC requires consideration of how to control the function of these serine proteases. The cornerstone of DIC treatment is treatment of the underlying pathology. However, in some cases surgery is either not possible or exacerbates the DIC associated with aortic aneurysm. In such cases, pharmacotherapy becomes even more important. Unfractionated heparin, other heparins, synthetic protease inhibitors, recombinant thrombomodulin, and direct oral anticoagulants (DOACs) are agents that inhibit serine proteases, and all are effective against DIC. Inhibition of activated coagulation factors by anticoagulants is key to the treatment of DIC. Among them, DOACs can be taken orally and is useful for outpatient treatment. Combination therapy of heparin and nafamostat allows fine-adjustment of anticoagulant and antifibrinolytic effects. While warfarin is an anticoagulant, this agent is ineffective in the treatment of DIC because it inhibits the production of coagulation factors as substrates without inhibiting activated coagulation factors. In addition, monotherapy using tranexamic acid in cases of enhanced-fibrinolytic-type DIC may induce fatal thrombosis. If tranexamic acid is needed for DIC, combination with anticoagulant therapy is of critical importance.

Clinical Features of Disseminated Intravascular Coagulation According to the French-American-British Classification in Patients With Acute Leukemia and Thrombomodulin Alfa Treatment-A Cohort Study Using a Postmarketing Surveillance Database

The aims of this study were to analyze the clinical features of a large number of cases with disseminated intravascular coagulation (DIC) associated with acute leukemia and to assess the safety and efficacy of thrombomodulin alfa (TM-α) using the French-American-British (FAB) classification of hematological malignancies. We retrospectively examined 644 patients with acute leukemia in postmarketing surveillance for TM-α. M3, M2, M4, M1, and M5 subtypes of acute myeloid leukemia (AML) and L2 and L1 subtypes of acute lymphoblastic leukemia (ALL) have been found more frequently among patients with DIC. Bleeding symptoms at baseline were more frequent in M3 and M7 subtypes. Fibrinogen concentrations were lower, and plasmin-plasmin inhibitor complex values were higher in M3 and Philadelphia-positive (Ph+) ALL. Overall DIC resolution rate was 60.2%, higher in L1 and Ph+ ALL, lower in M1, and generally higher in ALL than in AML. Overall survival rate was generally high, at 79.8%, with higher rates in L3, Ph+ ALL, and M3. Regardless of FAB subgroup, TM-α showed improved bleeding symptoms and DIC scores in clinical practice for DIC patients with acute leukemia.

Nafamostat in hospitalized patients with moderate to severe COVID-19 pneumonia: a randomised Phase II clinical trial

BACKGROUND

Nafamostat, a serine protease inhibitor, has been used for the treatment of disseminated intravascular coagulation and pancreatitis. In vitro studies and clinical reports suggest its beneficial effect in the treatment of COVID-19 pneumonia.

METHODS

This phase 2 open-label, randomised, multicentre, controlled trial evaluated nafamostat (4.8 mg/kg/day) plus standard-of-care (SOC) in hospitalised patients with COVID-19 pneumonia (i.e., those requiring nasal high-flow oxygen therapy and/or non-invasive mechanical ventilation). The primary outcome was the time to clinical improvement. Key secondary outcomes included the time to recovery, rates of recovery and National Early Warning Score (NEWS). The trial is registered with ClinicalTrials.gov Identifier: NCT04623021.

FINDINGS

A total of 104 patients, mean age 58.6 years were enrolled in 13 clinical centres in Russia between 25/9/2020 and 14/11/2020 and randomised to nafamostat plus SOC (n=53) or SOC alone (n=51). There was no significant difference in time to clinical improvement (primary endpoint) between the nafamostat and SOC groups (median 11 [interquartile range (IQR) 9 to 14) vs 11 [IQR 9 to 14] days; Rate Ratio [RR; the ratio for clinical improvement], 1.00; 95% CI, 0.65 to 1.57; p=0.953). In 36 patients with baseline NEWS ≥7, nafamostat was superior to SOC alone in median time to clinical improvement (11 vs 14 days; RR, 2.89; 95% CI, 1.17 to 7.14; p=0.012). Patients receiving nafamostat in this subgroup had a significantly higher recovery rate compared with SOC alone (61.1% (11/18) vs 11.1 % (2/18) by Day 11, p=0.002). The 28-day mortality was 1.9% (1/52) for nafamostat and 8.0% (4/50) for SOC (95% CI, -17.0 to 3.4; p=0.155). No case of COVID-19 related serious adverse events leading to death was recorded in the patients receiving nafamostat.

INTERPRETATION

Our study found no significant difference in time to clinical improvement between the nafamostat and SOC groups, but a shorter median time to clinical improvement in a small group of high-risk COVID-19 patients requiring oxygen treatment. To assess the efficacy further, a larger Phase 3 clinical trial is warranted.

FUNDING

Korea Research Institute of Bioscience and Biotechnology [2020M3A9H5108928] and Chong Kun Dang (CKD) Pharm (Seoul, Korea).

The clinically used serine protease inhibitor nafamostat reduces influenza virus replication and cytokine production in human airway epithelial cells and viral replication in mice

The effects of the clinically used protease inhibitor nafamostat on influenza virus replication have not been well studied. Primary human tracheal (HTE) and nasal (HNE) epithelial cells were pretreated with nafamostat and infected with the 2009 pandemic [A/Sendai-H/108/2009/(H1N1) pdm09] or seasonal [A/New York/55/2004(H3N2)] influenza virus. Pretreatment with nafamostat reduced the titers of the pandemic and seasonal influenza viruses and the secretion of inflammatory cytokines, including interleukin-6 and tumor necrosis factor-α, in the supernatants of the cells infected with the pandemic influenza virus. HTE and HNE cells exhibited mRNA and/or protein expression of transmembrane protease serine 2 (TMPRSS2), TMPRSS4, and TMPRSS11D. Pretreatment with nafamostat reduced cleavage of the precursor protein HA0 of the pandemic influenza virus into subunit HA1 in HTE cells and reduced the number of acidic endosomes in HTE and HNE cells where influenza virus RNA enters the cytoplasm. Additionally, nafamostat (30 mg/kg/day, intraperitoneal administration) reduced the levels of the pandemic influenza virus [A/Hyogo/YS/2011 (H1N1) pdm09] in mouse lung washes. These findings suggest that nafamostat may inhibit influenza virus replication in human airway epithelial cells and mouse lungs and reduce infection-induced airway inflammation by modulating cytokine production.

Physical compatibility of nafamostat with analgesics, sedatives, and muscle relaxants for coronavirus disease treatment

BACKGROUND

Severe coronavirus disease (COVID-19) may require continuous administration of analgesics, sedatives, and muscle relaxants. Nafamostat has recently been reported as a therapeutic agent for COVID-19. However, there is a lack of information on the compatibility of nafamostat with the aforementioned drug classes. This study evaluated the physical compatibility of nafamostat with these drug classes.

METHODS

Nafamostat was combined with 1-3 target drugs (fentanyl, morphine, midazolam, dexmedetomidine, and rocuronium). Fifteen physical compatibility tests were conducted. Nafamostat was dissolved in 5% glucose solution; the final concentration was 10 mg/mL. All other medications were diluted in 0.9% sodium chloride to obtain clinically relevant concentrations. The power of hydrogen (pH) of all medications was measured during each test. Compatibility tests were conducted with four test solutions wherein nafamostat and the target drugs were compounded at equal volume ratios (1:1, 1:1:1, or 1:1:1:1). Visual appearance, turbidity, and pH were evaluated immediately after mixing and at 1 and 3 hours. Physical incompatibilities were defined as gross precipitation, cloudiness, appearance of the Tyndall effect, or a turbidity change of ≥0.5 nephelometric turbidity unit (NTU) based on nafamostat.

RESULTS

The mean pH of nafamostat was 3.13 ± 0.03. The combination of nafamostat, fentanyl, and dexmedetomidine had the highest pH (3.39 ± 0.01; 3 hours after mixing). All drugs were compatible with nafamostat until 3 hours after admixture, with a mean turbidity value of <0.03 NTU.

CONCLUSIONS

Infusions combining nafamostat with the tested sedatives, analgesics, and muscle relaxants could be safely administered.

Possible Role of Electrolytes on the Formation of Precipitates during the Infusion of Nafamostat Mesilate in Hemodialysis

Nafamostat mesilate (NFM) is used as an anticoagulant during hemodialysis in patients who have had complications due to hemorrhages. The formation of precipitates, which could lead to the interruption of hemodialysis has been reported when NFM is infused into blood during hemodialysis. We report herein on an examination of possible factors that could cause this. The effects of electrolytes such as phosphates, citrates or succinates on the formation of precipitates were examined by mixing NFM with aqueous solutions or plasma that contained these electrolytes. The formation of precipitates was observed in all electrolyte solutions when higher concentrations of NFM were mixed at around physiological pH. In the case of plasma, precipitates were observed when solutions containing higher concentrations of NFM were mixed with plasma that contained phosphate and citrate. In addition, the formation of precipitates under dynamic conditions where NFM was infused into flowing electrolyte solutions was also evaluated. The data suggested that such precipitates might be formed and disrupt the blood flow and/or an NFM infusion when NFM is infused into blood flowing in the hemodialysis circuit. The findings presented herein suggest the serum levels of anionic electrolytes (e.g., phosphate), the type of excipients present in pharmaceutical products (e.g., succinic acid or citric acid), the concentration of NFM used for the infusion or the rates of NFM infusion and blood flow are all factors that could affect precipitate formation during NFM infusions for hemodialysis.

ACE2: the molecular doorway to SARS-CoV-2

The angiotensin-converting enzyme 2 (ACE2) is the host functional receptor for the new virus SARS-CoV-2 causing Coronavirus Disease 2019. ACE2 is expressed in 72 different cell types. Some factors that can affect the expression of the ACE2 are: sex, environment, comorbidities, medications (e.g. anti-hypertensives) and its interaction with other genes of the renin-angiotensin system and other pathways. Different factors can affect the risk of infection of SARS-CoV-2 and determine the severity of the symptoms. The ACE2 enzyme is a negative regulator of RAS expressed in various organ systems. It is with immunity, inflammation, increased coagulopathy, and cardiovascular disease. In this review, we describe the genetic and molecular functions of the ACE2 receptor and its relation with the physiological and pathological conditions to better understand how this receptor is involved in the pathogenesis of COVID-19. In addition, it reviews the different comorbidities that interact with SARS-CoV-2 in which also ACE2 plays an important role. It also describes the different factors that interact with the virus that have an influence in the expression and functional activities of the receptor. The goal is to provide the reader with an understanding of the complexity and importance of this receptor.

Management of disseminated intravascular coagulation associated with aortic aneurysm and vascular malformations

Aortic aneurysms and vascular malformations are sometimes associated with disseminated intravascular coagulation (DIC). A typical blood coagulation test shows decrease in platelet count and fibrinogen, and increases in fibrin/fibrinogen degradation products (FDP) and D-dimer. The coagulation activation marker thrombin-antithrombin complex (TAT) and the fibrinolysis activation marker plasmin-α₂ plasmin inhibitor (PIC) are significantly increased. α₂ plasmin inhibitor (α₂PI) is significantly reduced. Since no prolongation of prothrombin time (PT) is noticeable and activated partial thromboplastin time (APTT) is shortened in some cases, DIC cannot be diagnosed or ruled out by PT and APTT alone. The cornerstone of treatment for DIC is to treat the underlying disease. However, surgery is not possible in some cases. Follow-up may be appropriate in patients with abnormal results from coagulation tests and no bleeding. However, pharmacotherapy is often required in cases with bleeding. Unfractionated heparin, low molecular weight heparin, protease inhibitors, recombinant thrombomodulin, direct oral anticoagulants, and factor XIII preparations are effective. If PIC is significantly increased and α₂PI is significantly decreased, or if the bleeding is severe, tranexamic acid is used as an antifibrinolytic therapy with anticoagulant therapy. In such cases, attention should be paid not only to TAT but also changes in PIC.

Advances in the diagnosis and treatment of disseminated intravascular coagulation in haematological malignancies

Haematological malignancies, including acute leukaemia and non-Hodgkin lymphoma, are one of the underlying diseases that frequently cause disseminated intravascular coagulation (DIC), an acquired thrombotic disorder. Concomitant DIC is associated with the severity of the underlying disease and poor prognosis. The Japanese Society on Thrombosis and Hemostasis released the new DIC diagnostic criteria in 2017. This criteria include coagulation markers such as soluble fibrin and the thrombin-antithrombin complex to more accurately evaluate the hypercoagulable state in patients. Among several groups of anticoagulants available, recombinant human soluble thrombomodulin is most frequently used to treat DIC caused by haematological malignancies in Japan. DIC is remitted in parallel with the improvement of the underlying haematological diseases; thus, there is room for debate regarding whether the treatment of DIC would improve the prognosis of patients. Haematopoietic stem cell transplantation as well as the recently introduced chimeric antigen receptor (CAR)-T-cell therapy are innovative therapies to produce a cure in a subset of patients with haematological malignancies. However, coagulopathy frequently occurs after these therapies, which limits the success of the treatment. For example, DIC is noted in approximately 50% of patients after CAT-T-cell therapy in conjunction with cytokine release syndrome. Hematopoietic stem cell transplantation (HSCT) causes endotheliitis, which triggers coagulopathy and the development of potentially lethal complications, such as sinusoidal obstruction syndrome/veno-occlusive disease and transplant-associated thrombotic microangiopathy. This review article describes the pathogenesis, clinical manifestation, diagnosis, and treatment of DIC caused by haematological malignancies, CAR-T-cell therapy, and HSCT.

Predictors of early death, serious hemorrhage, and differentiation syndrome in Japanese patients with acute promyelocytic leukemia

Significant advancements have been achieved with regard to the outcomes of acute promyelocytic leukemia (APL) patients through the introduction of all-trans retinoic acid; however, early hemorrhagic death and differentiation syndrome remain the major causes of remission induction failure in patients with APL. To investigate early death, serious hemorrhage, and differentiation syndrome during remission induction therapy in terms of incidence, risk factors, influence on outcomes, and prophylactic effects of several new anticoagulants, the results of 344 patients enrolled in the Acute Promyelocytic Leukemia 204 study conducted by the Japan Adult Leukemia Study Group were analyzed. Early death was observed in 16 patients (4.7%), of whom 14 had serious hemorrhage and 2 had differentiation syndrome. Serious hemorrhage and differentiation syndrome of grade 2 or higher were observed in 21 and 54 patients, respectively. Patients who achieved complete remission had a 7-year disease-free survival of 84.8% if they did not experience serious hemorrhage and 40.0% if they experienced serious hemorrhage during remission induction therapy (P = 0.001). Risk factor analyses showed that higher white blood cell count was associated with early death, higher white blood cell count and lower platelet count with serious hemorrhage, and leukocytosis during induction therapy and higher body surface area with differentiation syndrome. In conclusion, these results indicate that patients with such high-risk features may benefit from more intensive supportive care. The hemorrhagic risk was not relieved by the introduction of new anticoagulants. Further studies are required to establish the predictive impact of body surface area on differentiation syndrome. This trial is registered with UMIN-CTR as C000000154 on September 13, 2005.

Comparison of Danaparoid Sodium and Synthetic Protease Inhibitors for the Treatment of Disseminated Intravascular Coagulation Associated with Hematological Malignancies: A Retrospective Analysis

BACKGROUND

Danaparoid sodium and synthetic protease inhibitors (SPIs) have been approved for the treatment of disseminated intravascular coagulation (DIC) in Japan.

OBJECTIVES

To compare the clinical results of the treatment of DIC with danaparoid or SPIs.

METHODS

We retrospectively examined 188 patients with hematological malignancy-related DIC.

RESULTS

DIC resolution rate in the danaparoid group was higher than that in the SPIs group (61.5 vs. 42.6%; p = 0.031) on day 7. Multivariate analysis identified the response to chemotherapy as independent predictive factor for DIC resolution on day 7 (odds ratio, OR, 2.28; 95% confidence interval, CI, 1.21-4.31; p = 0.011). While there was no significant difference in the DIC resolution rate on day 14 (75.0 vs. 62.4%; p = 0.117), in a subgroup analysis of patients who did not show an improvement in the underlying disease, the danaparoid group showed a significantly better DIC resolution rate (OR 3.89; 95% CI 1.15-13.2; p = 0.030). There was no difference in the rate of cumulative mortality from bleeding within 28 days between the 2 groups (6.6 vs. 3.3%; p = 0.278).

CONCLUSIONS

Danaparoid may be associated with more frequent resolution of DIC in patients with refractory underlying disease.

Emerging Therapeutic Modalities against COVID-19

The novel SARS-CoV-2 virus has quickly spread worldwide, bringing the whole world as well as the economy to a standstill. As the world is struggling to minimize the transmission of this devastating disease, several strategies are being actively deployed to develop therapeutic interventions. Pharmaceutical companies and academic researchers are relentlessly working to investigate experimental, repurposed or FDA-approved drugs on a compassionate basis and novel biologics for SARS-CoV-2 prophylaxis and treatment. Presently, a tremendous surge of COVID-19 clinical trials are advancing through different stages. Among currently registered clinical efforts, ~86% are centered on testing small molecules or antibodies either alone or in combination with immunomodulators. The rest ~14% of clinical efforts are aimed at evaluating vaccines and convalescent plasma-based therapies to mitigate the disease's symptoms. This review provides a comprehensive overview of current therapeutic modalities being evaluated against SARS-CoV-2 virus in clinical trials.

Nafamostat mesylate inhibits chlamydial intracellular growth in cell culture and reduces chlamydial infection in the mouse genital tract

Urogenital Chlamydia trachomatis (C. trachomatis) infection is one of the most common bacterial sexually transmitted diseases worldwide. Untreated C. trachomatis infections that ascend to the upper genital tract lead to a series of severe complications. To search for novel antichlamydial drugs, we evaluated the effect of nafamostat mesylate (NM), a synthetic serine protease inhibitor, on chlamydial infection. NM inhibited chlamydial intracellular growth and reduced both the inclusion size and number in cell culture. NM may mainly target the intracellular reticulate bodies for inhibition. NM was also effective in enhancing chlamydial clearance from mouse genital tract when NM was applied to mice via intravaginal inoculation. The vaginal NM did not significantly alter inflammatory cytokine responses in the mouse genital tract. Thus, we have demonstrated a novel role of NM in inhibiting the obligate intracellular bacterium Chlamydia.

Nafamostat mesylate attenuates the pathophysiologic sequelae of neurovascular ischemia

Nafamostat mesylate, an apparent soi-disant panacea of sorts, is widely used to anticoagulate patients undergoing hemodialysis or cardiopulmonary bypass, mitigate the inflammatory response in patients diagnosed with acute pancreatitis, and reverse the coagulopathy of patients experiencing the commonly preterminal disseminated intravascular coagulation in the Far East. The serine protease inhibitor nafamostat mesylate exhibits significant neuroprotective effects in the setting of neurovascular ischemia. Nafamostat mesylate generates neuroprotective effects by attenuating the enzymatic activity of serine proteases, neuroinflammatory signaling cascades, and the endoplasmic reticulum stress responses, downregulating excitotoxic transient receptor membrane channel subfamily 7 cationic currents, modulating the activity of intracellular signal transduction pathways, and supporting neuronal survival (brain-derived neurotrophic factor/TrkB/ERK1/2/CREB, nuclear factor kappa B. The effects collectively reduce neuronal necrosis and apoptosis and prevent ischemia mediated disruption of blood-brain barrier microarchitecture. Investigational clinical applications of these compounds may mitigate ischemic reperfusion injury in patients undergoing cardiac, hepatic, renal, or intestinal transplant, preventing allograft rejection, and treating solid organ malignancies. Neuroprotective effects mediated by nafamostat mesylate support the wise conduct of randomized prospective controlled trials in Western countries to evaluate the clinical utility of this compound.

Fibrinolysis Inhibitors: Potential Drugs for the Treatment and Prevention of Bleeding

Hyperfibrinolytic situations can lead to life-threatening bleeding, especially during cardiac surgery. The approved antifibrinolytic agents such as tranexamic acid, ε-aminocaproic acid, 4-aminomethylbenzoic acid, and aprotinin were developed in the 1960s without the structural insight of their respective targets. Crystal structures of the main antifibrinolytic targets, the lysine binding sites on plasminogen's kringle domains, and plasmin's serine protease domain greatly contributed to the structure-based drug design of novel inhibitor classes. Two series of ligands targeting the lysine binding sites have been recently described, which are more potent than the most-widely used antifibrinolytic agent, tranexamic acid. Furthermore, four types of promising active site inhibitors of plasmin have been developed: tranexamic acid conjugates targeting the S1 pocket and primed sites, substrate-analogue linear homopiperidylalanine-containing 4-amidinobenzylamide derivatives, macrocyclic inhibitors addressing nonprimed binding regions, and bicyclic 14-mer SFTI-1 analogues blocking both, primed and nonprimed binding sites of plasmin. Furthermore, several allosteric plasmin inhibitors based on heparin mimetics have been developed.

The Molecular Aspect of Antitumor Effects of Protease Inhibitor Nafamostat Mesylate and Its Role in Potential Clinical Applications

Nafamostat mesylate (NM), a synthetic serine protease inhibitor first placed on the market by Japan Tobacco in 1986, has been approved to treat inflammatory-related diseases, such as pancreatitis. Recently, an increasing number of studies have highlighted the promising effects of NM in inhibiting cancer progression. Alone or in combination treatments, studies have shown that NM attenuates various malignant tumors, including pancreatic, colorectal, gastric, gallbladder, and hepatocellular cancers. In this review, based on several activating pathways, including the canonical Nuclear factor-κB (NF-κB) signaling pathway, tumor necrosis factor receptor-1 (TNFR1) signaling pathway, and tumorigenesis-related tryptase secreted by mast cells, we summarize the anticancer properties of NM in existing studies both in vitro and in vivo. In addition, the efficacy and side effects of NM in cancer patients are summarized in detail. To further clarify NM's antitumor activities, clinical trials devoted to validating the clinical applications and underlying mechanisms are needed in the future.