key: cord-0769772-q7gkvf7p
authors: Scarabel, Lucia; Guardascione, Michela; Dal Bo, Michele; Toffoli, Giuseppe
title: Pharmacological strategies to prevent SARS-CoV-2 infection and to treat the early phases of COVID-19 disease
date: 2021-01-18
journal: Int J Infect Dis
DOI: 10.1016/j.ijid.2021.01.035
sha: 5c211777a1e1ed847b90c672c8b2fd1e5cafbe70
doc_id: 769772
cord_uid: q7gkvf7p

A novel coronavirus known as SARS-CoV-2 causing the human COVID-19 disease, emerged in China and is spreading worldwide. At present, a wide spectrum of different clinical scenarios occurred, ranging from totally asymptomatic to severe-fatal forms. Prevention remains the best approach against SARS-CoV-2 infection and a number of strategies have been adopted including social and medical interventions. Some vaccines have been proposed and several pharmacological approaches, mainly based on repurposing drugs, are currently under investigation and still need to be validated. In this review, we summarized the ongoing clinical trials using pharmacological strategies including vaccine, as prophylaxis to avoid SARS-CoV-2 infection or to limit its transmission and as early treatment of COVID-19 disease to prevent severe clinical outcomes.

On 11 th March 2020, the World Health Organization (WHO) announced the first pandemic due to the spreading of SARS-CoV-2, a novel positive-sense, single-stranded RNA betacoronavirus identified in humans in December 2019 in China, causing the COVID-19 disease (C. P. Zhou et al., 2020) . In the last years, 6 other outbreaks caused by coronavirus have been identified in humans, among them the SARS-CoV and MERS-CoV diseases have been found as the most pathogenic (Kuiken et al., 2003; Zaki et al., 2012; Zhong et al., 2003) and more recently the SARS-CoV-2 using the same cellular receptor as SARS-CoV, namely human angiotensin-converting enzyme 2 (hACE2) (Tai et al., 2020) .

The full clinical spectrum of COVID-19 severity has been defined in WHO reports (https://www.covid19treatmentguidelines.nih.gov/overview/clinical-spectrum/), ranging from asymptomatic to fatal forms. The most common symptoms at the onset of illness are fever, cough, myalgia or fatigue. Headache, diarrhea and dyspnea are less common (Chaolin Huang et al., 2020) .

Sepsis is the most frequently observed complication, followed by respiratory failure, acute respiratory distress syndrome, heart failure, and septic shock (F. .

It is widely known that preventing an infectious disease comprises primary, secondary and tertiary preventions (van Seventer and Hochberg, 2017) . Primary prevention aims to reduce new cases by interrupting the transmission of the microbiological agent to humans or increasing their resistance to Several other pharmacological strategies to prevent SARS-CoV-2 infection are currently under investigation and most still need to be validated for clinical utility (Sanders et al., 2020) . From a clinical point of view, most of the first available data were the result of retrospective studies, case reports and series (Sanders et al., 2020) ; few preliminary results from randomized clinical trials are now accessible (Cao et al., 2020; J. Chen et al., 2020; Hung et al., 2020; . No drugs clearly showed to have a relevant clinical benefit as pharmacological strat egy against COVID-19 in primary and secondary prevention. An exception is represented by remdesivir that is currently the only drug approved by FDA for the treatment of moderate/severe COVID-19 while in the earlier phases of infection the anti-SARS-CoV-2 antibodies are most likely to have an effect.

Remdesivir with or without dexamethasone is recommended for hospitalized patients who require supplemental oxygen (Information on Prevention and Research, n.d.) .

In this review, we summarize and critically analyze the ongoing clinical trials for pharmacological primary prevention of COVID-19 or in the early phase of infection (secondary prevention).

All asymptomatic individuals tested and resulted positive to SARS-CoV-2 or individuals positive to SARS-CoV-2 experiencing mild-to-moderate symptoms. For these two categories the aim of pharmacological interventions could be considered as "primary prevention" for the first population, and "secondary prevention" for the other.

We selected 98 out of 232 (42%) clinical trials which had the eligibility patients' criteria according to those previously reported as pharmacological prevention. The trial drugs in ongoing trials were divided in four classes: vaccines, antivirals, immune-based and others (Table 1) .

More than one hundred type of vaccines have been already proposed J o u r n a l P r e -p r o o f Jackson et al., 2020) , in phase II (NCT04405076) and II/III (NCT04649151) studies in 600 adults and 3000 children (12-17 years old), respectively, and in the COVE phase III trial (NCT04470427) in a total enrollment of 30000 adults (Baden et al., 2020) .

Another mRNA vaccine, CVnCoV vaccine was developed by CureVac and underway in a 

Non-replicating viral vector vaccines consist of a viral vector (mainly adenoviral-based vectors) in which genes have been cloned using recombinant DNA technique to produce the vaccine antigen(s) without the formation and dissemination of new viral particles. Voysey et al., 2020) .

CoV-2 spike protein, investigated in two randomized, placebo-controlled, double-blinded, phase II and III trials for healthy (NCT04566770) and high-risk people (NCT04526990).The hAd5-S-Fusion+N-ETSD vaccine is characterized by the expression of both SARS-CoV-2 spike and nucleocapsid protein though a human recombinant type 5 adenoviral-based vector and is under investigation in a phase I study (NCT04591717).

encoding the SARS-CoV-2 spike protein that has been evaluated in healthy people in a randomized, placebo-controlled, double-blinded, phase III (NCT04505722) trial. BBV152-Covaxin vaccine is being investigated in 25800 healthy people in a randomized, placebocontrolled, double-blinded, phase III trial (NCT04641481) in India.

Coronavac vaccine, is being tested in several phase III studies: the NCT04456595 trial for 8870

high-risk people in Brazil (Palacios et al., 2020) , the NCT04651790 for 2300 high-risk people in Chile, the NCT04508075 trial for 1620 healthy people in Indonesia, the NCT04617483 trial for 1040 healthy people in China, finally the phase I-II NCT04551547 trial for 552 healthy people in China.

The Inactivated SARS-CoV-2 vaccine is under investigation in 471 and 942 healthy people in a phase I (NCT04470609) and phase I-II (NCT04412538) trials (Che et al., 2020) .

Live-attenuated vaccines are generated by passaging in cell culture until they lost their pathogenic properties and become capable of causing only a mild infection upon administration. BCG, or bacille Calmette-Guérin, is a live-attenuated vaccine against tuberculosis and its protective non-specific effects against respiratory tract infection were evaluated in several countries and mainly in phase III-IV studies such as the BRACE trial in 4170 healthcare workers (NCT04327206). All the other BCG vaccine recruiting studies are reported in Table 1 . Also the measles-mumps-rubella (MMR) vaccine J o u r n a l P r e -p r o o f is under investigation for the effects against SARS-CoV-2 infection in phase III studies, both in healthy (NCT04357028) and in high-risk people (NCT04333732). Moreover, the oral polio vaccine with or without NA-831 is being tested in a phase IV for healthy volunteers (NCT04445428) and

phase III trial for high-risk people (NCT04540185).

The CIGB 2020 vaccine was proposed in combination with the conventional treatment in a phase I/II, randomized trial in 80 subjects (RPCEC00000306).

Chloroquine has been found to exert antiviral effects during pre-and post-coronavirus infections by interfering with the glycosylation of the hACE2, and blocking the fusion process of these viruses to the host cell (Zhou et al., n.d.) . Hydroxychloroquine, more soluble, has the same mechanism of action but a better safety profile than chloroquine. Hydroxychloroquine/chloroquine clinical trials against COVID-19, as reported in the Table 1 

A number of other compounds are under investigation in phase II and III trials as prophylaxis, such as melatonin among healthcare workers (NCT04353128), nicotine in caregivers (NCT04583410), nitazoxanide in healthcare workers (NCT04359680) and dietary supplement with vitamin D (IRCT20200401046909N2).

One hundred and thirty five out of 232 (58%) trials, were considered as pharmacological interventions in secondary prevention. Drugs in ongoing trials were divided in three classes:

antivirals, immune-based, and others (Table 2) .

Several drugs are currently being investigated as post-infection strategy to limit the spreading of the Ivermectin was also considered as antivirals against SARS-CoV-2 due to the results obtained in in vitro studies (Caly et al., 2020) . To date, several trials evaluating ivermectin are ongoing mainly in phase II studies as reported in Table 1 (NCT04392713, NCT04399746 

Remdesivir, a nucleotide prodrug of adenosine analog that binds to the viral RNA-dependent RNA polymerase inhibiting viral replication through premature termination of RNA transcription, was developed for the treatment of Ebola and MERS and SARS infection in animal models (Sheahan et al., 2017) . Although some results are available for remdesivir in moderate/severe COVID-19 (Goldman et al., 2020; Spinner et al., 2020) , a phase I-II study is still recruiting patients for evaluating its efficacy in 282 mild patients in early stages (NCT04539262). Other nucleoside analogs are being evaluated in several phase II-III trials (NCT04411433, NCT04387760, NCT04402203, NCT04464408, NCT04346628, NCT04499677, NCT04613271, NCT04575584, NCT04575597) in asymptomatic and mild/moderate patients. They include favipiravir, a purine-base analog prodrug (Joshi et al., 2021) and molnupiravir, a prodrug of nucleoside derivative N4-hydroxycytidine introducing copying errors during SARS-CoV-2 RNA replication (Cox et al., 2021) . Ribavirin plus long-acting interferon α-2a and triazavirin, two guanosine analog, are currently underway in patient with mild (ChiCTR2000030922) and mild-moderate, hospitalized patients (NCT04581915).

Anti-SARS-CoV-2 monoclonal antibodies such as bamlanivimab (LY3819253) 

In the very first phases of infection, the innate immune response has a fundamental role in recognizing and promptly counteracting the viral invasion and spread. Inflammatory cytokines act locally recruiting several immune cells such as monocytes, macrophages and NK cells that could early recognize and eliminate the infected cells, thus delaying viral outbreak into the tissues and blood. The Interleukine 6 (IL-6), like interferons, is a pleiotropic, pro-inflammatory cytokine (Tanaka et al., 2014) . Tocilizumab, targeting the IL-6 receptor, is approved in patients with rheumatologic disorders and cytokine release syndromes induced by chimeric antigen T cell (CAR-T) therapy and has been proposed for the early treatment of mild/moderate patients (NCT04332094, NCT04435717). CPI-006, a humanized monoclonal antibody anti-CD73, was evaluated as immunotherapy for hospitalized mild patients (NCT04464395).

Hempegaldesleukin, a PEGylated interleukin-2, was evaluated in mild patients (NCT04646044).

NT-I7, a long-acting immunoglobulin composed of recombinant endogenous human interleukin-7 and fused to a hybrid Fc region of a human antibody, with hematopoietic and immunopotentiating activities, is currently being evaluated in a phase I trial (NCT04501796 

and exert anti-inflammatory and immunomodulatory effects (Rogers et al., 2020) . The use of MSCs is being investigated for COVID-19 in a phase I/II, randomized trial evaluating the blood oxygen saturation (NCT04339660) and in a phase II/III, randomized trial in patients with mild-to-moderate COVID-19 considering as primary outcome the adverse effects (NCT04366063). Moreover, a phase II-III study evaluating the SBI-101, a biologic/device combination product designed to regulate inflammation and promote repair of injured tissue using allogeneic human mesenchymal stromal cells, is also ongoing (NCT04445220). Preliminary results of a pilot study in only 7 patients with moderate-to-severe COVID-19 are available, although this is not the object of a prevention strategy (Leng et al., 2020) . Another cell-based strategy, BACTEK-R (MV130), a bacterial preparation that contains a mixture of Gram inactivated bacteria, is currently being investigated in mild patients (NCT04363814).

Other drugs with immunomodulating activities such as estradiol patch, IMU-838, methotrexate-LDE, methotrexate associated to LDL like nanoparticles, and prazosin, an alpha-1 adrenergic J o u r n a l P r e -p r o o f receptor antagonist, are currently also being tested (NCT04359329, NCT04379271, NCT04610567, NCT04365257).

Drugs traditionally used as anticoagulants/antiaggregants have also been proposed in some phase II-to-III trials to reduce the risk of developing clotting problems in mild-to-moderate patients with COVID-19 disease: bemiparin (NCT04420299, NCT04604327), aggrenox (NCT04410328), enoxaparin (NCT04400799), rivaroxaban (NCT04508023, NCT04504032), rivaroxaban (NCT04504032) and atorvastatin (NCT04466241).

Tranexamic acid, inhibiting the conversion of plasminogen to plasmin and altering the endogenous protease plasmin, were also proposed to act as a SARS-CoV-2 entry inhibitor by cleaving a newly inserted furin site in the S protein and thus resulting in increased infectivity and virulence (NCT04338074) (Barker and Wagener, 2020; Ogawa and Asakura, 2020) .

Six aminoacids belonging to the receptor binding domain in the spike protein of SARS-CoV-2 have been shown to be critical for the viral entry mechanism through its binding to the hACE2 receptors (Lu et al., 2020) . To better establish the role of the angiotensin converting enzyme inhibitors (ACEis) and angiotensin receptor blockers (ARBs) some phase II-III trials are being conducted (NCT04493359, NCT04360551 with telmisartan, NCT04472728 with BIO101). J o u r n a l P r e -p r o o f

The SARS-CoV-2 pandemic has determined the need to develop safe and effective pharmacological drugs and vaccines for the prevention of infection. In the present review, we selected and analyzed the ongoing clinical trials of pharmacological prevention strategies for COVID-19 disease both in SARS-CoV-2 negative and positive, asymptomatic and mild-to-moderate, individuals focusing on the early phases of infection.

Methodological warnings should be considered for the trials we analyzed. In fact, for most of the studies, the therapeutic setting (prevention, early treatment, treatment of moderate-to-severe cases) of the investigating drug was not always clearly defined. Furthermore, the primary outcome and the eligible population were often heterogeneous. Moreover, size of enrolled population, especially in some registered trials, was restricted, thus reducing the statistical robustness of their results. However, at present, a clearer picture of the real clinical benefit of pharmacological prevention and early treatment is feasible compared to the beginning of the pandemic since some results of randomized trials are available.

Vaccines represent the best strategy of primary prevention. The traditional approaches adopted to develop vaccines show some limitations for their employment in the context of a pandemic. This is mainly due to the estimated time and specific instrument and laboratory structures that are needed.

To overcome these limits next-generation vaccine platforms have been used for SARS-CoV-2 vaccines. At present, 2 RNA-based vaccines (BNT162b2-Pfizer/BioNTech and mRNA-1273-Moderna) have been approved by FDA and EMA. This is the first time RNA-based vaccines produced with next-generation platforms have been approved for human. The approvals were based on the positive results obtained in two randomized, observer-blinded, placebo-controlled trials evaluating the safety after a median follow-up of 2 months and efficacy 7 days and 14 days after the second dose of BNT162b2 and mRNA-1273 vaccines in 18556 and 14134 subjects in the per-protocol analysis, J o u r n a l P r e -p r o o f respectively (Baden et al., 2020; Polack et al., 2020) . These vaccines conferred 95% and 94.1% efficacy at preventing COVID-19 disease, respectively. The introduction of new technologies in the vaccines' development and manufacturing during COVID-19 pandemic could have permanently globally changed the capability of rapidly counteracting other novel emerging viruses.

A plethora of antivirals, immune-based (anti-SARS-CoV-2 monoclonal antibodies, plasma-derived immunoglobulins, immunomodulators), and other drugs have been used in prevention and in early treatment, but no final conclusion can be driven from these studies.

At present remdesivir remains the only drug approved for the treatment of COVID-19, but its clinical benefit is narrow. The use of corticosteroids in severe COVID-19 disease resulted in improvement in organ supportfree (The Writing Committee for the REMAP-CAP Investigators et al., 2020), but no final conclusions are available for prevention and early treatment.

Trials evaluating hydroxychloroquine/chloroquine, the most speculated drugs in the earlier months of pandemic, have produced results showing that hydroxychloroquine did not prevent new COVID-19 disease or SARS-CoV-2 infection when used as prophylaxis in high-risk people (Abella et al., 2020; Boulware et al., 2020) neither reduce symptoms severity as early treatment in mild outpatients and mild-to-moderate patients (Cavalcanti et al., 2020) .

With regard to anti-SARS-CoV-2 antibodies, the interim analysis of BLAZE-1 trial demonstrated an acceleration of the natural decline in viral load after 11days from 2800mg administration of bamlanivimab (LY-CoV555) in mild/moderate patients and also a reduction of hospitalization rate (P. Chen et al., 2020) . A systematic review conducted on several studies investigating convalescent plasma, showed that this treatment could be safe and clinically effective, potentially reducing mortality in COVID-19 patients (Rajendran et al., 2020) .

In conclusion, this review represents an extensive report of the recruiting trials with drugs ranging from vaccines to antivirals to immune-based strategies, which are currently underway. Results from these studies could help to identify in the near future specific subgroups of individuals that could benefit from a pharmacological prevention or early treatment of COVID-19.

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

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The authors acknowledge Sara Colò, translator at the Experimental and Clinical Pharmacology Unit of CRO in Aviano, for editing the manuscript.

L.S., M.G, G.T. concepted and designed the study. L.S. and M.G. searched, summarized, and analyzed all data. M.G and G.T. provided the clinical support. L.S. realized the tables and the graphical abstract. L.S., M.G., and M.D.B. draft the manuscript. All authors critically revised and approved the final manuscript.

All the authors declare no conflict of interest.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

No ethical approval is needed.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

BioNTech MSCs, mesenchymal stem cells, ACEi, Angiotensin-converting-enzyme inhibitors, ARBs, angiotensin-receptor blockers, N/A, not available.