key: cord-0985175-v59dpmuu
authors: Magro, Giuseppe
title: COVID-19: review on latest available drugs and therapies against SARS-CoV-2. Coagulation and inflammation cross-talking
date: 2020-06-20
journal: Virus Res
DOI: 10.1016/j.virusres.2020.198070
sha: f7d49461db82053b2258177ac000d595bf0ac808
doc_id: 985175
cord_uid: v59dpmuu

SARS-CoV-2 is the agent responsible for COVID-19. The infection can be dived into three phases: mild infection, the pulmonary phase and the inflammatory phase. Treatment options for the pulmonary phase include: Hydroxychloroquine, Remdesivir, Lopinavir/Ritonavir. The inflammatory phase includes therapeutic options like Tocilizumab, Anakinra, Baricitinib, Eculizumab, Emapalumab and Heparin. Human clinical trials are starting to show some results, in some cases like that of Remdesivir these are controversial. Coagulopathy is a common complication in severe cases, inflammation and coagulation are intertwined and cross-talking between these two responses is known to happen. A possible amplification of this cross-talking is suggested to be implicated in the severe cases that show both a cytokine storm and coagulopathy.

Coronaviruses are enveloped, positive-sense, single stranded RNA viruses that are distributed broadly among humans which cause respiratory, enteric, hepatic, and neurologic diseases 1 . SARS-CoV-2 is the seventh member of the family of corona viruses that infects humans, after MERS-CoV and SARS-CoV-1, it is a beta coronavirus of group 2B with over 70% similarity in genetic sequence to SARS-CoV-1 2 . Some studies show that angiotensin-convertin enzyme 2 (ACE2) is the receptor for SARS-CoV-2 3, 4 . Structural analysis of the spike (S) protein of this new virus showed that its S protein is the one binding to the angiotensinconverting enzyme 2 (ACE2) receptor on human cells 5 . The incubation period is generally 3-7 days (within 14 days) 6 , mean incubation period is 5.2 days and 97,5% of patients who develop symptoms do so in the first 11,5 days 7, 8 . Symptoms of SARS-CoV-2 infection are nonspecific. The most common ones are onset on fever, weakness and dry cough. Less common symptoms are headache, myalgia, fatigue, oppression in the chest, dyspnea, sputum production, diarrhea 9 , confusion, sore throat, rhinorrhea, chest pain, nausea and vomiting 10 . Up to 50% of patients develop shortness of breath. Acute respiratory distress syndrome (ARDS)

is not an uncommon complication when disease can't be controlled 6 . The percentage of patients requiring ARDS treatment is about 10% for those who are hospitalized and symptomatic. Some patients are known to be asymptomatic carriers of the infection showing no clinical signs 6 . Usually severe patients are older and have chronic diseases, among those the most common associated diseases in severe cases are hypertension and cardiovascular diseases 11 . Total white blood count, lymphocytes, and platelets are lower than the average with extended activated thromboplastin time, increase C-reactive protein and muscle J o u r n a l P r e -p r o o f enzyme level. Lymphocytes decrease with diseases progression. Secretion of cytokine, such as IL1B, IL1RA, IL6, IL7, IL8, IL-2R, TNF-alfa, known as cytokine storm, is associated with disease severity 6, 11, 12 .

Here we present the drugs used in each phase. Another possible approach is to discuss every drug related to every phase of viral infection (Adhesion, Entry, Endocytosis, Replication, Protein cleavage, Cytokine Storm, Free circulation) as done in a previous study by the author 13 .

We basically have three phases of infection, the first one is the mild infection phase which only requires symptomatic treatment. Patient shows fever, with or without respiratory symptoms, no hypoxemia and negative imaging. This patient needs testing only if there is a high risk of contagion. It is important to perform a 6-minutes walking test before patient discharge to attest there is no exertional hypoxemia.

Pulmonary phase is the second phase which requires mostly antiviral treatment. Patient shows fever, bilateral pulmonary consolidations or hypoxemia. This patient needs to be hospitalized. The currently available options include: Hydroxychloroquine/Azithromycin, Remdesivir, Lopinavir/Ritonavir.

Hydroxychloroquine alters the process of endocytosis. Hydroxychloroquine is a derivate of chloroquine which alters pH (by increasing it) of endosome and lysosome essential for membrane fusion between host cell and the virus. Due to their basic properties and consequent disruption of cellular vesicle compartments, chloroquine and hydroxychloroquine may also inhibit virion budding and forming of mature virions 14 . An in vitro experiment showed that in chloroquine treated cells endosomes vesicles were abnormally enlarged 15 .

This indicates an altered maturation process of endosomes, blocking endocytosis, resulting in failure of further transport of virions to the replication site 15 . Hydroxychloroquine is being tested with azithromycin, and the association has shown some result in viral load reduction, but concern about prolonged QT interval arise with the association 16 . Chloroquine and hydroxychloroquine appear to block viral entry into cells not only by inhibition of endosomal acidification, but also by inhibition of glycosylation of host receptors and proteolytic processing, a critical passage of virus-cell ligand recognition. They may also impair the correct J o u r n a l P r e -p r o o f maturation and recognition of viral antigens by antigen-presenting cells (APCs) that require endosomal acidification for antigen processing 14 . This could be the explanation as to why they also have immunomodulatory effect through attenuation of cytokine production and inhibition of autophagy and lysosomal activity in host cells 17, 18 . Hydroxychloroquine inhibits IL-6, IL1-beta and TNF-alfa release 14 , and it showed also anti-thrombotic properties interfering with platelet aggregation and blood clotting proteins 14 .

An open-label nonrandomized study of 36 patients reported improved virologic clearance with hydroxychloroquine. They also reported that the addition of azithromycin to hydroxychloroquine resulted in superior viral clearance in some patients 16, 19 . Azithromycin has been shown to be active in vitro against Zika and Ebola viruses 16, 20, 21 , and to prevent severe respiratory tract infections when administrated to patients suffering viral infections 22 . Another prospective randomized study of 30 patients showed no benefit and no difference in virologic outcomes between the treated patients vs non treated 23 . Given the role of iron in several human viral infections, a potential involvement of Hydroxychloroquine in iron homeostasis in SARS-CoV-2 infection has been suggested 14 . Chloroquine and hydroxychloroquine are given orally and are generally well tolerated, however they can cause rare and serious effects such as QTc prolongation, hypoglycemia, neuropsychiatric effects and retinopathy. Known major drug-drug interactions happen with drugs who are also substrates of CYP2D6 and CYP3A4 24 . A randomized clinical trial of 62 patients from China suffering from COVID-19 showed how hydroxychloroquine shortens time to clinical recovery and absorption of pneumonia (ChiCTR2000029559) 25 . One study (NCT04261517, Phase 3) 26 showed positive preliminary outcomes, even though the sample was small.

Targeting the RNA-dependent RNA polymerase (RdRp) showed low specificity and low potency, nevertheless the most promising drug belonging to this class is Remdesivir 27, 28 . Remdesivir is one of the most promising antiviral in fighting SARS-CoV-2. It is an adenosine nucleotide analogue prodrug with broadspectrum activity against pneumoviruses, filoviruses, paramyxoviruses and coronaviruses 29 . It can inhibit J o u r n a l P r e -p r o o f the replication of multiple coronaviruses in respiratory epithelial cells. A recent study showed Remdesivir can compete with natural counterpart ATP. Once it is added to the growing chain, it does not cause an immediate stop but it stops the strand after 3 more nucleotides are added 28 . Remdesivir is currently being tested for antiviral activity against Ebola virus 30 

The Main protease is another suitable drug target, one example in doing so is the combination of Lopinavir/Ritonavir 27 . Lopinavir/ritonavir is a medication for the human immunodeficiency virus (HIV) used in combination with other medications to treat adults and children who are infected with HIV-1. Lopinavir in particular is an HIV-1 protease inhibitor, its combination with ritonavir has shown to be effective against SARS-CoV-1 in patients and in tissue culture, via inhibition of 3-chymotripsin-like protease (3CLpro), the main protease 35, 36 . The combination of the two also reduced clinical scores and disease progression in animals infected with MERS-CoV 37 . Previous studies showed the combination of lopinavir and ritonavir to be of some use for SARS-CoV-1 and MERS-CoV infected patients 38 . Clinical studies in SARS-CoV-1 were associated with reduced mortality and intubation rates 38, 39 . Both anti-HIV drugs interacted well with the residues at the active site of SARS-CoV-2 3CLpro. Ritonavir showed a somewhat higher number atomic contacts, a somewhat higher binding efficiency, and higher number of key binding residues compared to lopinavir, which correspond with the slightly lower water accessibility at the 3CLpro active site 40 

The inflammatory phase is the third phase, which leads to the most common complication of COVID-19

which is ARDS. Patient shows fever, severe hypoxemia with partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) ratio <300 and multiple pulmonary consolidations. 

High levels of interleukin 6 (IL-6) and Interleukin 8 (IL-8) were found in the acute stage associated with lung lesions in SARS-CoV-1 patients. Especially IL-6 can induce the hyper-inflammatory response due to the SARS-CoV-1 invasion of the respiratory tract 47 . Interestingly, in human epithelial cells, SARS-CoV-1 was able to induce greater IL-6 when compared to influenza A virus 48 . Although in some murine viral infections IL-6 plays a protective and essential role in the resolution process, in others like in SARS-CoV-1 high levels of IL-6

were associated with severe inflammation and correlated with mortality in the mice 49, 50 . This happens also with SARS-CoV-2 in COVID-19 patients: some retrospective and meta-analysis studies show how elevated J o u r n a l P r e -p r o o f IL-6 and C-reactive protein (CRP) correlate with mortality and severe disease in comparison to moderate disease [51] [52] [53] [54] . More evidence suggests that critically ill patients with severe respiratory failure and SARS-CoV-2 have either immune dysregulation or macrophage-activation syndrome, both of which are characterized by pro-inflammatory cytokines. The immune dysregulation, in particular, is driven by the Interleukin-6 (IL- 6) and not by Interleukin-1beta (IL-1beta) 54 . Interestingly, among all SARS-CoV-1 structural proteins (N, S, E and M), the nucleocapsid protein (N) significantly induced the activation of IL-6 promotor in human airway epithelial cell cultures 55 . IL-6 gene expression is activated by the N protein which binds to the NF-kB regulatory element on IL-6 promoter and facilitates its translocation from cytosol to nucleus. The N protein is essential for IL-6 secretion to happen, since deletion of the C-terminus of the N protein resulted in the loss of function in the activation of IL-6 55 . This again points towards excessive activation of the innate immune response. Another proof of that is the damage shown to the pulmonary interstitial arteriolar walls that is more associated with the inflammatory response rather than the pathogenic effect of CoVs 56 Major effects include hematologic effects, infections, gastrointestinal perforations and hypersensitivity reactions. Interactions with several CYP450 isoenzymes are described 24 . Interestingly, Tocilizumab targets both IL-6 receptor (IL-6R) forms: the soluble one (sIL-6R) and the membrane bound one (mIL-6R). Those two forms seem to work in very divergent ways, since the soluble one is believed to be pro-inflammatory, and the membrane bound IL-6 Receptor is believed to act in an anti-inflammatory way 58 , inhibiting only the pro-inflammatory one could then be a better option then targeting them both 59 . Sarilumab, another antibody against IL-6 receptor used in rheumatoid arthritis 60 , is being tested in a multicenter, double-blind, J o u r n a l P r e -p r o o f clinical phase 2/3 in patients with severe COVID-19 (NCT04315298) 24 . Other drugs that showed potential inhibition of IL-6 related JAK/STAT pathway are: Fingolimod which showed to inhibit proliferation and epithelial-mesenchymal transition in sacral chordoma by inactivating IL-6/STAT3 signaling 61 , a clinical trial in COVID-19 patients is ongoing (NCT04280588, Phase2) 26 ; glatiramer acetate showed potential to downregulate both IL-17 and IL-6 in the central nervous system in an autoimmune encephalitis model 62 .

Another option in fighting the cytokine storm is targeting IL-1 with Canakinumab, a monoclonal antibody against IL-1-beta, which is being approved by the Italian drug agency (AIFA) in COVID-19 pneumonia. It is used for the treatment of familial Mediterranean fever and it has been shown to be of use in atherosclerotic diseases for its anti-inflammatory properties 63, 64 . A clinical phase 2 trial is ongoing in patients with COVID-19 pneumonia with Canakinumab (NCT04362813) 26 .

Anakinra is also another option in targeting IL-1 Receptor, which is used for rheumatoid arthritis 65 . Anakinra is being tested with Tocilizumab in a phase 2 clinical trial (NCT04339712) 26 . It is also being tested in COVID-19 patients combined with Emapalumab (NCT04324021, Phase2/3 multicenter randomized clinical trial) 26 .

Emapalumab is a human monoclonal antibody against interferon gamma which acts to block its binding to cell surface receptors and activation of inflammatory signals, it is used to treat the severe inflammatory condition of hemophagocytic lymphohistiocytosis (HLH) 66 .

After the SARS-CoV-2 infection, CD4+T lymphocytes are rapidly activated to become pathogenic T helper PT and APTT compared to survivors on admission; more than 70% of non survivors met the criteria of disseminated intravascular coagulation (DIC) during hospitalization 71 . It has also become clear that COVID-19-related DIC is not a bleeding diathesis but rather a predominantly prothrombotic DIC with high venous thromboembolism rates, elevated D-dimer and fibrinogen levels, low anti-thrombin levels. The use of anticoagulant therapy with heparin was shown to decrease mortality 72 . This was especially so in patients who meet the sepsis induced coagulopathy (SIC) criteria (a score >= 4 is required) and in patients with markedly elevated D-dimer 72 . This suggest that Low molecular weight heparin (LMWH) at prophylactic dose should be considered in patients meeting SIC criteria and elevated D-dimer. Heparin showed, besides its primary known use, to have also anti-inflammatory properties [73] [74] [75] , that could be of therapeutic value in those patients with severe lung inflammation and impaired pulmonary exchange. ARDS is a common complication of COVID-19. Activation of coagulation system has been linked to ARDS onset. It has been shown that the median plasma concentrations of tissue factor and plasminogen activator inhibitor-1 were J o u r n a l P r e -p r o o f significantly higher at day seven in patients with ARDS, as compared to non-ARDS 76 . Coagulopathy arises from thrombin generation mediated by localized tissue factor, and depression of fibrinolysis mediated by plasminogen activator in the lungs, in accordance with an increase in plasminogen activator inhibitor-1 (PAI-1) 76, 77 . This again points towards how heparin might be helpful in fighting this coagulopathy. Another interesting therapeutic property of heparin is its supposed antiviral role 78 . Heparin showed to inhibit infection in experimental vero cells injected with sputum from a patient with SARS-CoV-1 pneumonia 79 .

Recently, Cui and colleagues, reported the prevalence of venous thromboembolism (VTE) in 81 severe COVID-19 patients with pneumonia admitted in the intensive care unit. The incidence in these patients of VTE (not under thromboprophylaxis) was 25% and eventually 40% of them died 80 . Increased levels of D-Dimer predicted VTE with a sensitivity of 85%, specificity of 88.5% and negative predictive value of 94% 80 .

The prevalence of VTE in ICU patients with COVID-19 pneumonia reported by Cui is higher than the prevalence of VTE associated with other diseases: in a meta-analysis of seven studies including 1783 ICU patients, the mean rate of VTE diagnosis was 12.7, thus suggesting a direct role of COVID-19 in VTE pathogenesis 81 . Moreover, coagulopathy is known to happen in the majority of patients who die of COVID-19 71 . This suggests that severe COVID-19 patients are at high VTE risk and mortality risk and anticoagulant therapy might improve their prognosis 82 

The activation of both the immune system and the coagulation system are not simply associated in time, but there is extensive crosstalk between the two systems 87 . Upon injury by a micro-organism, immune cells are recruited and many pro-inflammatory cytokines are secreted, and these cytokines are key mediators of activation of coagulation 88 . Moreover, inflammation not only leads to activation of coagulation, but coagulation also affects inflammatory activity 87 . Acute infections can alter hemodynamics, clotting and fibrinolytic systems leading to ischemic events 89 . This is what might happen with SARS-CoV-2 infection too.

High levels of IL-6 and IL-8 have been associated to SARS-CoV-1 and SARS-CoV-2 as already mentioned above, and high levels of these cytokines also correlate with mortality. There is also a clear connection that has been proven between inflammatory events and the development of thrombovascular disease in many clinical scenarios 90 . Complications like venous thromboembolism (VTE) has been connected to inflammation and some results showed that patients with VTE have higher plasma levels of interleukin-8 (IL-8) then those without VTE 90, 91 . Both IL-6 and IL-8 have a role in activation of coagulation, and higher levels of these cytokines may correlate with higher rate of VTE events 90, 91 , this also might happen in the lungs in patients with severe COVID-19 pneumonia. It has been reported how IL-8 production directly correlates with thrombin-antithrombin (TAT) complex 92 . Abnormal clot lysis was observed in the presence of IL-1 beta, IL-6 and IL-8, using thromboelastography. Interestingly, IL-8 shows the most significant results in thromboelastography (TEG) analysis making the clot form faster (hypercoagulation), with an increase in cross-linking fibrin fibers. IL-8 showed also to be able to alter erythrocyte structure and its addition produced a clot with an increased time to clot formation that is less stable and more prone to early lysis 88 .

Thus, the clotting risk with increased levels of IL-8 might result in the presence of small thrombi, with an increased risk for vessels occlusion as observed in some COVID-19 patients autopsies 93 . Inflammation stimulates coagulation by leading to intravascular tissue factor expression and down regulation of the fibrinolytic pathway 94 . Interestingly, IL-6 is responsible for one of the main mechanism whereby inflammation activates coagulation by inducing tissue factor (TF) expression 87, 95, 96 . Moreover IL-6 can increase the expression of fibrinogen, factor VIII and VWF, activation of endothelial cells and increase platelets production and reduce the levels of inhibitors of haemostasis such as antithrombin and protein S 97 . It has been reported how IL-6 can also elicits a dose-dependent acceleration of thrombus development in arterioles of a WT mice 98 . IL-6 can also cause the clot to form faster and in a less stable form, and causes a more hypercoagulable clot then IL-1 beta; but IL-8 is still the most potent procoagulant cytokine between those three: causing the most significant changes at all levels of coagulation, including fibrin, thrombin and cellular interactions 99 . IL-8 promotes procoagulant activity, by triggering also platelet activation 100 . This is evidence of how cytokines and inflammation activate coagulation.

Moreover, activation of coagulation in healthy human subjects by the administration of recombinant factor VIIa also elicits a small but significant increase in the concentrations of IL-6 and IL-8 in plasma 101 . Thrombin too has been shown to have many non-coagulant effects, among these there is IL-6 induction in fibroblasts, epithelial cells and mononuclear cells in vitro 102 and induction of IL-8 production in endothelial cells 103 . This is evidence of a well-known cross-talking between inflammations and coagulation, and of a possible loop mechanism which could be amplified in a setting like that of COVID-19.

Targeting the endocytosis process is also possible with other drugs other than hydroxychloroquine. One known regulators of endocytosis is the AP2-associated protein kinase 1(AAK1). Using Artificial Intelligence it was possible to find a good inhibitor of AAK1 like Baricitinib, a known Janus kinase inhibitor which can reduce both viral entry and inflammation. It is a selective and powerful JAK-STAT signaling inhibitor thus being effective against the consequences of the elevated levels of cytokines, not only being able of J o u r n a l P r e -p r o o f lowering IL-6 levels 104 , but it also has the potential to inhibit clathrin-mediated endocytosis and thereby inhibit viral infection of cells. It targets members of the numb-associated kinase (NAK) family ( AAK1 and GAK), the inhibition of which has been shown to reduce viral infection in vitro 105 . It can be administered orally and has acceptable side effect profile, besides having little interaction with CYP enzymes and drug transporters 106 , since renal elimination is the principal clearance mechanism for Baricitinib 107 . It regulates innate immunity through blocking type-I IFN signal. Baricitinib downregulates CD80/CD86 expression, but not that of HLA-DR in human monocyte-derived dendritic cells in a concentration-dependent manner.

Moreover, assessment of the action of Baricitinib on plasmacytoid dendritic cells (pDC), which are the main source of type-I IFN, showed suppressed production of type-I IFN 107 . This makes Baricinitib a valid option in every phase of the viral infection, the early stages to reduce viral entry in the cells, and later stages for its anti-inflammatory properties. A Phase2/3 clinical trial is ongoing (NCT04340232) 26 .

Since high levels of IL-6 is the results or this excessive inflammatory response, one way to target IL-6 is with antibodies like Tocilizumab, another way is to counteract the response induced by IL-6. This can be done by inhibiting the JAK 1/2 pathway with drugs like Ruxolitinib. Ruxolitinib is a small drug belonging to the class of Janus kinase (JAK) inhibitors and currently clinically used in the treatment of JAK2 mutated myeloproliferative neoplasms, including myelofibrosis and polycythemia vera 108, 109 . It shows activity against the JAK2 isoform and also the JAK1 isoform, which plays a major role in the signaling pathway of inflammatory cytokines 110 . JAK3 seems to be less sensitive to ruxolitinib 111 , it also shows anti-inflammatory activity which may be beneficial in its clinical use 112 ; it is also implicated in the suppression of the harmful consequences of macrophage activation hemophagocytic lymphohistiocytosis 113 , which is an underrecognized hyperinflammatory syndrome characterized by fulminant and fatal hypercytokinemia with multi organ failure 114 . It has been proven that the expression of major inflammatory cytokines such as TNF alfa and IL-6 was highly reduced in inflammatory human macrophages exposed to ruxolitinib 112 . It has also been shown through an analysis of mRNA expression of cytokines by PCR array that the major inflammatory cytokines , IL-6 and TNF alfa, were highly reduced and down-regulated by Ruxolitinib at both protein and J o u r n a l P r e -p r o o f mRNA level 115 . Ruxolitinib has many effects on many types of cells like Natural Killers (NKs), Dendritic Cells (DCs), and T cells. NKs are usually reduced after Ruxolitinib administration, this happens after NKs maturation is impaired. Ruxolitinib profoundly impairs DCs migration; subsequently, the loss of trafficking DCs may lead to reduced activation of T cells in draining lymph nodes 116 . Also Treg cells are negatively regulated with Ruxolitinib 116 . All these results point towards a possible use of Ruxolitinib as an IL-6 inhibitor like Tocilizumab in the advanced stages of COVID-19, a trial is ongoing(NCT04334044, Phase1/2) 26 . Table 1 summarizes the main therapeutic options that have been discussed here (Table 1) .

We discussed the most valid options against COVID-19, but many new alternatives arise every day. Future possible treatments are discussed here. Inhibiting the receptor ACE2 seemed like a reasonable strategy but at the moment is controversial and has shown many possible side effects 117 . Another interestingly choice is to use a recombinant form of the ACE2 receptor to "keep the virus busy" and thus reduce the infected number of the cells by inhibiting the first phase, this has particularly been tested in patients with ARDS in the past 118 . Another option is targeting viral entry: cleavage and activation of SARS-CoV-1 spike protein (S) by a host cell protease is essential for viral entry, this host cell protease is called TMPRSS2. Potential in vitro proven inhibitors are camostat mesylate 119 27 , another recently discovered in vitro protease inhibitor is compound 13b, which is a modified alfa-ketoamide 121 .

Coagulopathy and inflammatory response are intertwined as already discussed. Both the presence of coagulation disfunction and the excessive activation of inflammatory response point towards and excessive J o u r n a l P r e -p r o o f activation of the complement system. In a murine model lacking C3 and thus unable to activate the common complement pathway, SARS-CoV-1 infection severity was reduced 122 . In a murine model of MERS-CoV infection, increased concentrations of C5a and C5b were found in the serum and in lung tissues 123 . This suggests a possible use of Eculizumab, a C5 complement inhibitor, to both prevent coagulation disorder and hyper-inflammation activation (NCT04288713) 26 .

Targeting viral components such as the spike proteins of the virus with specific antibodies is another therapeutic option which is currently being tested 124 . Neutralizing Antibodies are active during the free circulation of the virus. Coronaviruses neutralizing antibodies usually target the spike proteins(S) on the viral surface of the virus which allow it to enter host cells. The S protein has two subunits: one that mediates cell binding, S1 consisting of 4 domains, and one that mediates cell fusion, the S2 domain. The most neutralizing antibodies are shown to target the receptor interaction site in S1 subunit [125] [126] [127] [128] [129] [130] [131] . As shown in previous studies spike proteins of SARS-CoV-2 and SARS-CoV-1 are 77.5% identical by primary amino acid sequence and structurally very similar 132, 133 , they bind the ACE2 protein 134 through the S1 subunit(S1B).

The latest developed antibodies showing neutralizing properties is the Human 47D11 antibody, which was shown to target the S1B receptor binding domain of SARS-CoV-1 and SARS-CoV-2. Despite its capacity to inhibit infected cells with SARS-CoV-1 and SARS-CoV-2, the binding activity did not compete with S1B to the ACE2 receptor. This seems to indicate that 47D11 neutralizes SARS-CoV-1 and SARS-CoV-2 through a yet unknown mechanism different from binding interference 124 . This study shows how, despite the high capability of the virus to mutate, targeting conserved core structure of the S1B receptor is a good strategy. This provides evidence for the design of the SARS-CoV-2 vaccine composed of viral structural proteins.

Another possible choice is Ivermectin, which showed to inhibit viral replication of SARS-CoV-2 in vitro 135 , but in vivo studies need to evaluate its effect, clinical trials in COVID-19 are ongoing(NCT04390022, Phase 2).

The use of immunosuppressants like corticosteroids is quite controversial, for some it may be reasonable to counteract the effect of cytokine storm induced by the SARS-CoV-2. Although the recent open label study J o u r n a l P r e -p r o o f from Wu and colleagues showed a benefit for corticosteroids, for now clinical evidence does not support corticosteroid treatment for SARS-CoV-1 lung injury, as it could result in delayed viral clearence 136, 137 . Table 2 summarizes other therapeutic options that have been discussed here (Table 2 ).

In conclusions the author showed a list of possible therapies, many are being tested in clinical trials as we speak, some still need more testing. This review aimed to give an update on currently available therapies, already known drugs discussed here could have the advantage of speeding up the clinical trial process, since we already known their side effects and tolerability.

The author declares no conflict of interest.

J o u r n a l P r e -p r o o f

Hydroxychloroquine 14, 15, 16, 18, 20, 21, 22, 25, 26 Inhibition of endosomal acidification, inhibition of glycosylation of host receptors and proteolytic processing 14 . Immunomodulatory effect 14, 18 Interaction with Spike protein Ivermectin 135, 26 Inhibition of in vitro replication NCT04390022, Phase 2 Corticosteroids 136, 137 Immunosuppression NCT04273321 Table 2 

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Coagulopathy and Antiphospholipid Antibodies in Patients with Covid-19

Abnormal coagulation parameters are associated with poor prognosis in patients with novel coronavirus pneumonia

Anticoagulant treatment is associated with decreased mortality in severe coronavirus disease 2019 patients with coagulopathy

More than an anticoagulant: Do heparins have direct antiinflammatory effects?

The anti-inflammatory effects of heparin and related compounds

Heparin, heparan sulfate and heparanase in cancer: remedy for metastasis?

Activation of Coagulation and Fibrinolysis in Acute Respiratory Distress Syndrome: A Prospective Pilot Study

Bronchoalveolar hemostasis in lung injury and acute respiratory distress syndrome

Herpesviruses and heparan sulfate: an intimate relationship in aid of viral entry

Coronaviridae and SARS-associated coronavirus strain HSR1

Prevalence of venous thromboembolism in patients with severe novel coronavirus pneumonia

The impact of deep vein thrombosis in critically ill patients: a meta-analysis of major clinical outcomes

Thromboembolic risk and anticoagulant therapy in COVID-19 patients: emerging evidence and call for action

COVID-19 Coagulopathy in Caucasian patients

COVID-19-Related Severe Hypercoagulability in Patients Admitted to Intensive Care Unit for Acute Respiratory Failure

ISTH interim guidance on recognition and management of coagulopathy in COVID-19

The relationship between inflammation and the coagulation system

Simultaneous presence of hypercoagulation and increased clot lysis time due to IL-1beta, IL-6 and IL-8

Inflammation and atherosclerosis

Interleukin 8 and venous thrombosis: evidence for a role of inflammation in thrombosis

Activation of innate immunity in patients with venous thrombosis: the Leiden Thrombophilia Study

The proinflammatory cytokine response to coagulation and endotoxin in whole blood

Autopsy Findings and Venous Thromboembolism in Patients With COVID-19: A Prospective Cohort Study

Inflammation, sepsis, and coagulation

Two-way interactions between inflammation and coagulation

Inflammation and coagulation

Interleukin 6 and haemostasis

Interleukin-6 mediates the platelet abnormalities and thrombogenesis associated with experimental colitis

Effects of IL-1beta, IL-6 and IL-8 on erythrocytes, platelets and clot viscoelasticity

Platelet activation induced by human antibodies to interleukin-8

Activation of coagulation by administration of recombinant factor VIIa elicits interleukin 6 (IL-6) and IL-8 release in healthy human subjects

Potential mechanisms for a proinflammatory vascular cytokine response to coagulation activation

Protease-activated receptors 1 and 4 mediate activation of human platelets by thrombin

Baricitinib-induced blockade of interferon gamma receptor and interleukin-6 receptor for the prevention and treatment of graft-versus-host disease

Anticancer kinase inhibitors impair intracellular viral trafficking and exert broad-spectrum antiviral effects

COVID-19: combining antiviral and anti-inflammatory treatments. The Lancet Infectious Diseases

Baricitinib for the treatment of rheumatoid arthritis and systemic lupus erythematosus: a 2019 update

Safety and efficacy of INCB018424, a JAK1 and JAK2 inhibitor, in myelofibrosis

Emerging treatments for classical myeloproliferative neoplasms

Ruxolitinib, a selective JAK1 and JAK2 inhibitor for the treatment of myeloproliferative neoplasms and psoriasis

Preclinical characterization of the selective JAK1/2 inhibitor INCB018424: therapeutic implications for the treatment of myeloproliferative neoplasms

The impact of ruxolitinib treatment on inflammation-mediated comorbidities in myelofibrosis and related neoplasms

Therapeutic effect of JAK1/2 blockade on the manifestations of hemophagocytic lymphohistiocytosis in mice

COVID-19: consider cytokine storm syndromes and immunosuppression

Repression of interferon betaregulated cytokines by the JAK1/2 inhibitor ruxolitinib in inflammatory human macrophages

Mechanisms Underlying the Antiinflammatory and Immunosuppressive Activity of Ruxolitinib

Identification of critical determinants on ACE2 for SARS-CoV entry and development of a potent entry inhibitor

A pilot clinical trial of recombinant human angiotensin-converting enzyme 2 in acute respiratory distress syndrome

Simultaneous treatment of human bronchial epithelial cells with serine and cysteine protease inhibitors prevents severe acute respiratory syndrome coronavirus entry

Protease inhibitors targeting coronavirus and filovirus entry

Crystal structure of SARS-CoV-2 main protease provides a basis for design of improved α-ketoamide inhibitors

Complement Activation Contributes to Severe Acute Respiratory Syndrome Coronavirus Pathogenesis

Blockade of the C5a-C5aR axis alleviates lung damage in hDPP4-transgenic mice infected with MERS-CoV

A human monoclonal antibody blocking SARS-CoV-2 infection

Structural basis for the divergence of substrate specificity and biological function within HAD phosphatases in lipopolysaccharide and sialic acid biosynthesis

Structural Basis for the Regulation of the MmpL Transporters of Mycobacterium tuberculosis

Structural basis for outer membrane lipopolysaccharide insertion

Structural basis for the interaction of lipopolysaccharide with outer membrane protein H (OprH) from Pseudomonas aeruginosa

Structural basis for activation of an integral membrane protease by lipopolysaccharide

Structural basis for full-spectrum inhibition of translational functions on a tRNA synthetase

Towards a solution to MERS: protective human monoclonal antibodies targeting different domains and functions of the MERS-coronavirus spike glycoprotein

Cryo-EM structure of the 2019-nCoV spike in the prefusion conformation

Structure, Function, and Antigenicity of the SARS-CoV-2 Spike Glycoprotein

Angiotensin-converting enzyme 2 is a functional receptor for the SARS coronavirus

The FDA-approved Drug Ivermectin inhibits the replication of SARS-CoV-2 in vitro

Clinical evidence does not support corticosteroid treatment for 2019-nCoV lung injury

Risk Factors Associated With Acute Respiratory Distress Syndrome and Death in Patients With Coronavirus Disease