Human Anti-Ace2 Monoclonal Antibodies as Pan-Sarbecovirus Prophylactic Agents

Background: Human monoclonal antibodies from convalescent individuals that target the SARS-CoV-2 spike protein have been deployed as therapeutics against SARS-CoV-2. However, nearly all of these antibodies have been rendered obsolete by SARS-CoV-2 variants that evolved to resist similar, naturally occurring antibodies. Moreover, Most SARS-CoV-2 specific antibodies are inactive against divergent sarbecoviruses Methods: By immunizing mice that carry human immunoglobulin variable gene segments we generated a suite of fully human monoclonal antibodies that bind the human ACE2 receptor (hACE2) rather than the viral spike protein and were engineered to lack effector functions such as ADCC. Result(s): These ACE2 binding antibodies block infection by all hACE2 binding sarbecoviruses, including emergent SARS-CoV-2 variants, with a potency that of the most potent spike binding therapeutic antibodies. Structural and biochemical analyses revealed that the antibodies target an hACE2 epitope that engages SARS-CoV-2 spike. Importantly, the antibodies do not inhibit hACE2 enzymatic activity, nor do they induce ACE depletion from cell surfaces. The antibodies exhibit favorable pharmacology in human ACE2 knock in mice and provide near complete protection of hACE2 knock-in mice against SARS-CoV-2 infection. Conclusion(s): ACE2 binding antibodies should be useful prophylactic and treatment agents against any current and future SARS-CoV-2 variants, as well as hACE2-binding sarbecoviruses that might emerge as future pandemic threats.

Characterization of the C6D7-RBD Human Monoclonal Antibody Specific to the SARS-CoV-2 S Protein Receptor-Binding Domain.

The new coronavirus infection COVID-19 is an acute viral disease that affects primarily the upper respiratory tract. The etiological agent of COVID-19 is the SARS-CoV-2 RNA virus (Coronaviridae family, Betacoronavirus genus, Sarbecovirus subgenus). We have developed a high-affinity human monoclonal antibody, called C6D7-RBD, which is specific to the S protein receptor-binding domain (RBD) from the SARS-CoV-2 Wuhan-Hu-1 strain and exhibits virus-neutralizing activity in a test with recombinant antigens: angiotensin-converting enzyme 2 (ACE2) and RBD.

Identification and Analysis of Monoclonal Antibodies with Neutralizing Activity against Diverse SARS-CoV-2 Variants.

We identified neutralizing monoclonal antibodies against severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) variants (including Omicron variants BA.5 and BA.2.75) from individuals who received two doses of mRNA vaccination after they had been infected with the D614G virus. We named them MO1, MO2, and MO3. Among them, MO1 showed particularly high neutralizing activity against authentic variants: D614G, Delta, BA.1, BA.1.1, BA.2, BA.2.75, and BA.5. Furthermore, MO1 suppressed BA.5 infection in hamsters. A structural analysis revealed that MO1 binds to the conserved epitope of seven variants, including Omicron variants BA.5 and BA.2.75, in the receptor-binding domain of the spike protein. MO1 targets an epitope conserved among Omicron variants BA.1, BA.2, and BA.5 in a unique binding mode. Our findings confirm that D614G-derived vaccination can induce neutralizing antibodies that recognize the epitopes conserved among the SARS-CoV-2 variants. IMPORTANCE Omicron variants of SARS-CoV-2 acquired escape ability from host immunity and authorized antibody therapeutics and thereby have been spreading worldwide. We reported that patients infected with an early SARS-CoV-2 variant, D614G, and who received subsequent two-dose mRNA vaccination have high neutralizing antibody titer against Omicron lineages. It was speculated that the patients have neutralizing antibodies broadly effective against SARS-CoV-2 variants by targeting common epitopes. Here, we explored human monoclonal antibodies from B cells of the patients. One of the monoclonal antibodies, named MO1, showed high potency against broad SARS-CoV-2 variants including BA.2.75 and BA.5 variants. The results prove that monoclonal antibodies that have common neutralizing epitopes among several Omicrons were produced in patients infected with D614G and who received mRNA vaccination.

Dupilumab as a steroid-sparing treatment option in pediatric severe asthma and chronic rhinosinusitis with nasal polyps

Case report Chronic rhinosinusitis with nasal polyps (CRSwNP) is a frequent comorbidity in severe asthma in adults. Both diseases share key pathophysiological mechanisms that can involve type-2 inflammatory pathways. However, this is an uncommon presentation in pediatric patients. Dupilumab, a fully human monoclonal antibody against IL-4Ralpha, inhibits IL-4/ IL-13 signaling, which are key drivers of type-2 inflammation and interfere with both eosinophilic and allergic pathways. It is approved for patients >= 12-year- old with moderate to severe uncontrolled asthma, but its approval in CRSwNP is limited to adults. We report a case of a 12-year- old boy with severe uncontrolled asthma and highly symptomatic CRSwNP referred to our center in May 2021. He was sensitized to house dust mite and pollens, and a specific immunotherapy had been tried previously. He was treated with high dose inhaled corticosteroid, long-acting beta agonist, long-acting muscarinic antagonist, montelukast and daily intra-nasal corticosteroids. Furthermore, a bilateral endoscopic sinus surgery with polypectomy was performed in April 2021. Despite adherence to medication and surgical treatment, both diseases were uncontrolled with frequent exacerbations requiring unscheduled visits and multiple systemic corticosteroid courses. This led to failure to thrive and several missed school days. Oral corticosteroid (OCS) tapering was unachieved due to symptoms rebound and so maintenance therapy with prednisolone 10mg daily was attempted, with only a slight improvement. High levels of eosinophils (1010 cells/muL), FeNO (122 ppb) and IgE (2255 kU/L) were present. Treatment with subcutaneous dupilumab was started in July 2021. A clinical and analytical improvement was evident at the 3-month evaluation (Table 1). He was able to stop prednisolone, and no clinically relevant exacerbations occurred. He also was fully vaccinated and had an asymptomatic COVID-19 infection in December 2021. Patients with CRSwNP and comorbid asthma have a higher disease burden than patients with each disease alone. In this adolescent, dupilumab was effective as an add-on treatment, for both severe asthma and CRSwNP. It led to disease control, OCS withdrawal, reduced eosinophilic inflammation, improved lung function, smell recovery and absence of exacerbations during follow-up. Dupilumab, targeting the type 2 inflammatory process, may allow a better management of pediatric patients >=12 years old with severe CRSwNP and comorbid asthma. (Table Presented).

SARS-CoV-2 Therapy: Old Drugs as New Interventions

An outburst of a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has become a grave threat to global health and the economy. As of May 13, 2020, a total of 42,81,838 cases have been confirmed, with over 2,92,376 deaths worldwide. In India, 75,048 cases have been reported to date with 2,440 deaths. Management of this new coronavirus (COVID19) has mainly focused on infection prevention, case detection, monitoring, and supportive care. As there is no vaccine or specific antiviral treatment for human SARS-CoV-2, therefore identifying the drug treatment options as soon as possible is critical for the response to the COVID19 outbreak. Pro-inflammatory cascade and cytokine storm play a key role in the pathogenesis of new coronavirus. A large number of therapeutic interventions such as antiviral, antimalarial, convalescent plasma therapy, BCG vaccine, mTOR inhibi-tors, Tissue Plasminogen Activator, Human monoclonal antibodies, Anti-parasitic agents, Immunoen-hancers, Nutritional interventions, JAK-STAT signaling inhibitors, ACE2 receptor modulators, and An-giotensin II receptor blockers have been either tried or suggested for effective treatment of patients with SARS-CoV-2 disease. Hence, we recommend that all the above potential interventions must be imple-mented in terms of their safety and efficacy through proper clinical experiments to control the emerging SARS-CoV-2 disease.Copyright © 2021 Bentham Science Publishers.

Human monoclonal antibodies to the spike subdomain 1 neutralize SARS-CoV-2 and its variants of concern

Progress in the fight against COVID-19 is jeopardized by the emergence of SARS-CoV-2 variants that diminish or abolish the efficacy of vaccines and antiviral monoclonal antibodies. Novel immune therapies are therefore needed, that are broadly effective against present and future coronavirus threats. In principle, this could be achieved by focusing on portions of the virus that are both functionally relevant and averse to change. The Subdomain 1 (SD1) of SARS-CoV-2 Spike protein is adjacent to the RBD and its sequence is conserved across SARS-CoV-2 variants, except for substitutions A570D in Alpha (B.1.1.7) and T547K in Omicron BA.1 (B.1.1.529). In order to specifically identify and study human antibodies targeting SD1, we designed a flow cytometry-based strategy that combines negative selection of B cells binding to the Receptor Binding Domain (RBD) with positive selection of those binding to SD1-RBD fusion protein. Among the 15 produced human monoclonal antibodies, 6 are SD1-specific. 3 of them cross-react with SD1-RBDs corresponding to all six variants of concern and 2 are neutralizing SARS-CoV-2 pseudovirus. Antibody sd1.040 also neutralizes Delta, Omicron BA.1 and Omicron BA.2 pseudovirus, synergizes with an antibody to the RBD for neutralization, and protects mice when present in a bispecific antibody. Thus, naturally occurring antibodies can neutralize SARS-CoV-2 variants by binding to SD1 and can act synergistically against SARS-CoV-2 in preclinical models.

Research Progress of Monoclonal Antibody Technology and Analysis of Marketed Drugs

Since the establishment of hybridoma in the 1980s, the antibody technology has achieved great development.Antibody is an immunoglobulin secreted by B lymphocytes, which produces many biological activity, such as blocking, neutralization, activation, kill target cells and regulate immune system via Fc receptor.The development of antibody technology has undergone a long history of mouse monoclonal antibodies, chimeric antibodies, humanized antibodies, and full human monoclonal antibodies.In the transition from mouse antibody to human antibody, a variety of biotechnology breakthroughs have been achieved, such as antibody library technology, humanized mouse technology and B cell cloning technology.Today, antibody drugs have a pivotal position throughout the drug market.Ten years come (2 011.01~2 021.11), 78 monoclonal antibody drugs have been approved for marketing by FDA, are widely distributed in the field of tumor disrases, immune diseases, anti-pathogen infections, nerves, etc.This article reviews monoclonal antibody technologies and antibody drug listing, and provides ideas for the preparation of new antibodies and the choice of drug target.

A combination of two human neutralizing antibodies prevents SARS-CoV-2 infection in cynomolgus macaques.

BACKGROUND: Human monoclonal antibody (mAb) treatments are promising for COVID-19 prevention or therapy. The pre-exposure prophylactic efficacy of neutralizing antibodies that are engineered with mutations to extend their persistence in human serum and the neutralizing antibody titer in serum required for protection against SARS-CoV-2 infection remain poorly characterized. METHODS: The Fc region of two neutralizing mAbs (COV2-2130 and COV2-2381) targeting non-overlapping epitopes on the receptor binding domain of SARS-CoV-2 spike protein was engineered to extend their persistence in humans and reduce interactions with Fc gamma receptors. We assessed protection by individual antibodies or a combination of the two antibodies (designated ADM03820) given prophylactically by an intravenous or intramuscular route in a non-human primate (NHP) model of SARS-CoV-2 infection. FINDINGS: Passive transfer of individual mAbs or ADM03820 conferred virological protection in the NHP respiratory tract in a dose-dependent manner, and ADM03820 potently neutralized SARS-CoV-2 variants of concern in vitro. We defined a protective serum-neutralizing antibody titer and concentration in NHPs for passively transferred human antibodies that acted by direct viral neutralization. CONCLUSIONS: In summary, we demonstrate that neutralizing antibodies with extended half-life and lacking Fc-mediated effector functions are efficient for pre-exposure prophylaxis of SARS-CoV-2 infection in NHPs. These results support clinical development of ADM03820 for COVID-19 prevention. FUNDING: This research was supported by a contract from the JPEO-CBRND (W911QY-20-9-003, 20-05); the Joint Sciences and Technology Office and Joint Program Executive Office (MCDC-16-01-002 JSTO, JPEO); a DARPA grant (HR0011-18-2-0001); an NIH grant (R01 AI157155); and the 2019 Future Insight Prize from Merck KGaA.

RBD-SPECIFIC POLYCLONAL F(ab)2 FRAGMENTS of EQUINE ANTIBODIES in PATIENTS with MODERATE to SEVERE COVID-19 DISEASE

SARS-CoV-2, the causative agent of COVID-19, is currently generating a global pandemic. So far, dexamethasone and remdesivir have shown efficacy in adequately powered clinical trials. In addition, passive immunotherapy appears as a promising therapeutic approach, particularly for early stages of the disease in which patients have not yet established their specific immune response. Different anti-receptor binding domain (RBD) human monoclonal antibodies (mAbs) have been evaluated in the treatment of COVID-19. It has been previously shown that the RBD from the viral spike glycoprotein elicits high titers of NAbs against SARS-CoV-2 when used as immunogen in horses. In this regard, equine polyclonal antibodies (EpAbs) can represent a practical and efficient source of NAbs. EpAbs are composed of F(ab)'2 fragments generated by pepsin digestion. These fragments retain the bivalent binding capacity of IgG immunoglobulins but lack the constant region (Fc), responsible for serum sickness reactions and Fc-triggered side effects. EpAbs recognize a vast array of epitopes (limiting the risk of viral escape mutations) and tend to develop greater avidity than mAbs for their cognate antigens. In addition, EpAbs are relatively easy to manufacture allowing a fast development and scaling up for a treatment. We have previously described the development and in vitro characterization of a therapeutic based on purified equine anti-RBD F(ab)2 fragments, called INM005. INM005 shows a very high serum neutralization titer against SARS-CoV-2. We conducted a phase 2/3 clinical to test the therapeutic effect of INM005 on COVID-19 patients. Albeit not having reached the primary endpoint, we found clinical improvement of hospitalized patients with SARS-CoV-2 pneumonia, particularly those with severe disease. Rate of improvement in at least two categories was statistically significantly higher for INM005 at days 14 and 21 of follow-up. Time to improvement in two ordinal categories or hospital discharge was 14·2 (± 0·7) days in the INM005 group and 16·3 (± 0·7) days in the placebo group. Subgroup analyses showed a beneficial effect of INM005 over severe patients and in those with negative baseline antibodies. Overall mortality was 6·9% the INM005 group and 11·4% in the placebo group. Adverse events of special interest were mild or moderate;no anaphylaxis was reported. Based on these results, ANMAT granted the emergency use approval of INM005 to treat hospitalized COVID-19 severe patients. Following approval, more than 20,000 patients have been treated with INM005. We will be presenting the results of the "real world use of this immunotherapy during the second wave of the pandemics in Argentina.

Structural Basis of a Human Neutralizing Antibody Specific to the SARS-CoV-2 Spike Protein Receptor-Binding Domain.

The emerging new lineages of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have marked a new phase of coronavirus disease 2019 (COVID-19). Understanding the recognition mechanisms of potent neutralizing monoclonal antibodies (NAbs) against the spike protein is pivotal for developing new vaccines and antibody drugs. Here, we isolated several monoclonal antibodies (MAbs) against the SARS-CoV-2 spike protein receptor-binding domain (S-RBD) from the B cell receptor repertoires of a SARS-CoV-2 convalescent. Among these MAbs, the antibody nCoV617 demonstrates the most potent neutralizing activity against authentic SARS-CoV-2 infection, as well as prophylactic and therapeutic efficacies against the human angiotensin-converting enzyme 2 (ACE2) transgenic mouse model in vivo. The crystal structure of S-RBD in complex with nCoV617 reveals that nCoV617 mainly binds to the back of the "ridge" of RBD and shares limited binding residues with ACE2. Under the background of the S-trimer model, it potentially binds to both "up" and "down" conformations of S-RBD. In vitro mutagenesis assays show that mutant residues found in the emerging new lineage B.1.1.7 of SARS-CoV-2 do not affect nCoV617 binding to the S-RBD. These results provide a new human-sourced neutralizing antibody against the S-RBD and assist vaccine development. IMPORTANCE COVID-19 is a respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The COVID-19 pandemic has posed a serious threat to global health and the economy, so it is necessary to find safe and effective antibody drugs and treatments. The receptor-binding domain (RBD) in the SARS-CoV-2 spike protein is responsible for binding to the angiotensin-converting enzyme 2 (ACE2) receptor. It contains a variety of dominant neutralizing epitopes and is an important antigen for the development of new coronavirus antibodies. The significance of our research lies in the determination of new epitopes, the discovery of antibodies against RBD, and the evaluation of the antibodies' neutralizing effect. The identified antibodies here may be drug candidates for the development of clinical interventions for SARS-CoV-2.

Structures and therapeutic potential of anti-RBD human monoclonal antibodies against SARS-CoV-2.

Background: Administration of potent anti-receptor-binding domain (RBD) monoclonal antibodies has been shown to curtail viral shedding and reduce hospitalization in patients with SARS-CoV-2 infection. However, the structure-function analysis of potent human anti-RBD monoclonal antibodies and its links to the formulation of antibody cocktails remains largely elusive. Methods: Previously, we isolated a panel of neutralizing anti-RBD monoclonal antibodies from convalescent patients and showed their neutralization efficacy in vitro. Here, we elucidate the mechanism of action of antibodies and dissect antibodies at the epitope level, which leads to a formation of a potent antibody cocktail. Results: We found that representative antibodies which target non-overlapping epitopes are effective against wild type virus and recently emerging variants of concern, whilst being encoded by antibody genes with few somatic mutations. Neutralization is associated with the inhibition of binding of viral RBD to ACE2 and possibly of the subsequent fusion process. Structural analysis of representative antibodies, by cryo-electron microscopy and crystallography, reveals that they have some unique aspects that are of potential value while sharing some features in common with previously reported neutralizing monoclonal antibodies. For instance, one has a common VH 3-53 public variable region yet is unusually resilient to mutation at residue 501 of the RBD. We evaluate the in vivo efficacy of an antibody cocktail consisting of two potent non-competing anti-RBD antibodies in a Syrian hamster model. We demonstrate that the cocktail prevents weight loss, reduces lung viral load and attenuates pulmonary inflammation in hamsters in both prophylactic and therapeutic settings. Although neutralization of one of these antibodies is abrogated by the mutations of variant B.1.351, it is also possible to produce a bi-valent cocktail of antibodies both of which are resilient to variants B.1.1.7, B.1.351 and B.1.617.2. Conclusions: These findings support the up-to-date and rational design of an anti-RBD antibody cocktail as a therapeutic candidate against COVID-19.

Impact of Host Immune Status on Discordant Anti-SARS-CoV-2 Circulating B Cell Frequencies and Antibody Levels.

Individuals with pre-existing chronic systemic low-grade inflammation are prone to develop severe COVID-19 and stronger anti-SARS-CoV-2 antibody responses. Whether this phenomenon reflects a differential expansion of antiviral B cells or a failure to regulate antibody synthesis remains unknown. Here, we compared the antiviral B cell repertoire of convalescent healthcare personnel to that of hospitalized patients with pre-existing comorbidities. Out of 277,500 immortalized B cell clones, antiviral B cell frequencies were determined by indirect immunofluorescence screening on SARS-CoV-2 infected cells. Surprisingly, frequencies of SARS-CoV-2 specific clones from the two groups were not statistically different, despite higher antibody levels in hospitalized patients. Moreover, functional analyses revealed that several B cell clones from healthcare personnel with low antibody levels had neutralizing properties. This study reveals for the first time a key qualitative defect of antibody synthesis in severe patients and calls for caution regarding estimated protective immunity based only on circulating antiviral antibodies.

SARS-CoV-2 neutralizing antibody development strategies.

In December 2019 a novel coronavirus was detected in Wuhan City of Hubei Province-China. Owing to a high rate of transmission from human to human, the new virus called SARS-CoV-2 differed from others by its unexpectedly rapid spread. The World Health Organization (WHO) described the most recent coronavirus epidemic as a global pandemic in March 2020. The virus spread triggered a health crisis (the COVID-19 disease) within three months, with socioeconomic implications. No approved targeted-therapies are available for COVID-19, yet. However, it is foreseen that antibody-based treatments may provide an immediate cure for patients. Current neutralizing antibody development studies primarily target the S protein among the structural elements of SARS-CoV-2, which mediates the cell entry of the virus through the angiotensin converting enzyme 2 (ACE2) receptor of host cells. This review aims to provide some of the neutralizing antibody development strategies for SARS-CoV-2 and in vitro and in vivo neutralization assays.