EXPERIENCE IN THE USE OF NEUTRALIZING MONOCLONAL ANTIBODIES IN KIDNEY TRANSPLANT RECIPIENTS WITH COVID-19.

Therapy with neutralizing monoclonal antibodies (mAbs) is particularly relevant during COVID-19 outbreaks in patients at high risk of severe disease, including kidney transplant recipients (KTRs). Objective(s): to evaluate the efficacy and safety of neutralizing mAbs in KTRs with mild to moderate COVID-19. Materials and methods. The retrospective study included 99 KTRs who received inpatient treatment for COVID-19 between September 1 and December 31, 2021. Patients were 52.0 +/- 11.5 years old (M, 47.5%). Bamlanivimab/etesevimab combination drug at a dose of 700/1400 mg was used as mAbs. To evaluate the efficacy of mAbs therapy, two groups of patients were identified. Group 1 consisted of 33 KTRs who received mAbs as one of the therapy components, while group 2 consisted of 66 patients who received no mAbs. Discharge from the hospital or death was considered as the endpoint of follow-up. Results. In group 1, after the use of mAb, progression of pulmonary process was observed less frequently than in the control group with CT1-2 transformation to CT3-4 (9.1% vs. 30.3%, respectively, p < 0.01). Group 1 KTRs differed significantly from group 2 - lower need for ICU and ventilator care (6.1% vs. 27.3% and 3% vs. 19.8%, respectively). The groups were comparable by sex, age, body mass index, Charlson Comorbidity Index (CCI) and time after kidney transplant (KTx) at the onset of the disease and by aseline blood biochemistry parameter values at the time of hospitalization. Only C-reactive protein (CRP) and fibrinogen values were higher in the non-mAbs patients who were hospitalized later in the course of the disease (7.7 +/- 3.2 days versus 4.6 +/- 1.6 days in group 1, p < 0.001). The frequency of prescription of other therapies did not differ between the compared groups. Use of mAbs significantly reduced mortality from 19.7% in KTRs in group 2 to 3% in group 1 without adverse effect on graft function. Conclusion. The use of mAbs therapy in the early stages of COVID-19 in KTRs is safe, it prevents severe COVID-19, and reduces the incidence of adverse outcomes.Copyright © 2023 Russian Transplant Society. All rights reserved.

EXPERIENCE WITH TIXAGEVIMAB AND CILGAVIMAB (EVUSHELD) IN 86 RHEUMATIC PATIENTS UNDERGOING ANTI-B CELL THERAPY WITH RITUXIMAB.

The problem of prevention of coronavirus disease 2019 (COVID-19) in patients with immune-mediated inflammatory rheumatic diseases (IMRD) remains highly relevant. The presence of IRD is associated with a high risk of disease and severe course of COVID-19 during immunosuppressive treatment, primarily anti-B cell therapy with rituximab (RTX), and a low level of post-vaccination response in such patients. A new strategy for the prevention and treatment of COVID-19 are virus-neutralizing monoclonal antibodies to coronavirus;currently, combined long-acting monoclonal antibodies tixagevimab and cilgavimab (Evusheld) are registered for prevention in the world and the Russian Federation. . Tixagevimab and cilgavimab (TC) show neutralizing activity against SARS-CoV-2, including the Omicron strain, primarily its variants BA.4, BA.5, BA.2.75 ("Centaur"). Objective - to evaluate the efficacy and safety of TC for pre-exposure prophylaxis of COVID-19 in rheumatic patients receiving RTX, based on a prospective observational study. Materials and methods. The main group included 86 patients with various IMRD receiving RTX: 50 of them had ANCA-associated systemic vasculitis (AAV), 15 - rheumatoid arthritis, 9 - Sjogren's syndrome (SS), 4 - IgG4-related disease, 3 - systemic lupus erythematosus (SLE), 3 - dermatomyositis (DM), 2 - systemic scleroderma (SSD). Median age was 59 (19-82) years;male: female ratio - 1:1,8. From March 26 to August 30 2022, patients received a single intramuscular injection of TC in a total dose of 300 mg, mainly after RTX (in 52% of cases, in 28% on the next day after RTX). The control group included 42 patients with AAV (median age - 45 (35-71) years;male: female ratio - 1:1), also treated with RTX, who did not receive pre-exposure prophylaxis of TC. The duration of observation was 7 months, until November 1 2022. At this time, 98% of confirmed cases of coronavirus in the Russian Federation were Omicron. A telephone and/or online survey of patient has been conducted to detect cases of COVID-19 and adverse reactions. Results. In the TC group, confirmed coronavirus infection have been detected in 17 (20%) patients (AAV - 10, SS - 3, SSD - 2, SLE - 1, DM - 1), with fever in 7 (8%), only in one case hospitalization was required (lung damage was not detected in computed tomography), in two cases, according to CT mild lung damage (CT 1-2), there were no deaths. Good TC's tolerability was noted, signs not associated with COVID-19 or progression of IMRD after administration of TC were observed in 8 (9%) patients (GPA - 3 MPA - 1, RA - 2, SLE - 1, IgG4-related disease - 1), adverse reactions definitely associated with the use of TC were not found. The most serious event not associated with coronavirus infection was the progression of polyneuropathy in a patient with RA. In the control group, 3 (7%) patients were diagnosed with COVID-19, one with severe lung injury (CT 3, pulmonary embolism) and death. Conclusions. The data of clinical studies and our own clinical experience evidence the effectiveness of the use of a combination of long-acting monoclonal antibodies TC (Evusheld), registered for indications for pre-exposure prophylaxis and treatment of COVID-19. Patients with IMRD treated with RTX have a favorable safety profile of TC. The introduction of virus-neutralizing monoclonal antibodies, a new drug class for the prevention and treatment of infectious diseases, opens significant prospects for improving the prognosis of patients with IRD.Copyright © 2023 Ima-Press Publishing House. All rights reserved.

Efficacy and Safety of Anti-SARS-CoV-2 Monoclonal Antibodies: An Updated Review.

Monoclonal antibodies (mAbs) had received emergency use authorization for mild-to-moderate coronavirus disease 2019 (COVID-19) or for prophylaxis against COVID-19, including casirivimab plus imdevimab (C+I), bamlanivimab plus etesevimab (B+E), tixagevimab plus cilgavimab (T+CG), and sotrovimab (S) and bebtelovimab (BEB). This systematic review was done to assess the efficacy and safety of the same. PubMed, Embase, Scopus, medRxiv, bioRxiv, and FDA fact sheets were searched for the studies published between January 2021 and May 2022, and appropriate search terms related to the mentioned mAbs were used for data collection. Review included original research including randomized clinical trials and observational studies published or preprints. Studies included in the review had compared with placebo or standard of care or no treatment or mAbs with each other and also of various doses. Data extraction was done and reviewed the same for both efficacy and safety. Total of 20 studies were included in this review. The rate of hospitalization within 30 days showed ∼2% in comparison to ∼7% with placebo. Significant reduction in viral load was more observed with combination mAbs. Combination therapy showed faster virological cure against the Gamma variant. With C + I as postexposure prophylaxis (PEP), 29.0% of asymptomatic participants developed symptomatic COVID-19. Pre-exposure prophylaxis with T+CG reduced the incidence of infection by 77%. Infusion-related reaction was the most common adverse event (AE). The neutralizing mAbs reduced hospitalization in mild-to-moderate patients with infusion-related reactions as common AE. The response was better in the seronegative patients. Most of these studies were conducted in unvaccinated individuals and against Alpha, Gamma, and Delta variants.

Neutralizing monoclonal antibodies in haematological patients paucisymptomatic for COVID-19: The GIMEMA EMATO-0321 study.

COVID-19 continues to be a relevant issue among patients with haematological malignancies (HM). Vaccines are frequently not effective in subjects on active treatment. In this multicentre retrospective study of Gruppo Italiano Malattie EMatologiche dell'Adulto (GIMEMA), we collected data from 91 paucisymptomatic HM patients treated with anti-spike neutralizing monoclonal antibodies (nMoAbs) to determine time to viral clearance, referencing it to the expected value of 28 days from an historical group of untreated paucisymptomatic patients. Secondary endpoints included rate of hospitalization, intensive care unit (ICU) admission, COVID-19 related death and safety. SARS-CoV-2 molecular swab negativity was obtained in 86 patients (95%), with a median time of 18 days (IQR 13-26; p < 0.0001). We did not find significant variations according to age, diagnosis, treatment type, vaccination status or nMoAbs type. Rate of hospitalization due to COVID-19 progression was 12% (11/91), with 2 patients (2.2%) requiring ICU admission. With a median follow-up of 2.33 months, the overall mortality was 5.5% (5/91), with 3 deaths due to COVID-19. Side effects were rare and self-limiting. Our data suggest that nMoAbs can limit the detrimental effect of immunosuppressive treatments on COVID-19 clinical progression and time to viral clearance. The original trial was registered at www.clinicaltrials.gov as #NCT04932967.

Characterization of SARS-CoV-2 Escape Mutants to a Pair of Neutralizing Antibodies Targeting the RBD and the NTD.

Mutations in the spike protein of SARS-CoV-2 can lead to evasion from neutralizing antibodies and affect the efficacy of passive and active immunization strategies. Immunization of mice harboring an entire set of human immunoglobulin variable region gene segments allowed to identify nine neutralizing monoclonal antibodies, which either belong to a cluster of clonally related RBD or NTD binding antibodies. To better understand the genetic barrier to emergence of SARS-CoV-2 variants resistant to these antibodies, escape mutants were selected in cell culture to one antibody from each cluster and a combination of the two antibodies. Three independently derived escape mutants to the RBD antibody harbored mutations in the RBD at the position T478 or S477. These mutations impaired the binding of the RBD antibodies to the spike protein and conferred resistance in a pseudotype neutralization assay. Although the binding of the NTD cluster antibodies were not affected by the RBD mutations, the RBD mutations also reduced the neutralization efficacy of the NTD cluster antibodies. The mutations found in the escape variants to the NTD antibody conferred resistance to the NTD, but not to the RBD cluster antibodies. A variant resistant to both antibodies was more difficult to select and only emerged after longer passages and higher inoculation volumes. VOC carrying the same mutations as the ones identified in the escape variants were also resistant to neutralization. This study further underlines the rapid emergence of escape mutants to neutralizing monoclonal antibodies in cell culture and indicates the need for thorough investigation of escape mutations to select the most potent combination of monoclonal antibodies for clinical use.

Early Use of Sotrovimab in Children: A Case Report of an 11-Year-Old Kidney Transplant Recipient Infected with SARS-CoV-2.

BACKGROUND: The use of virus-neutralizing monoclonal antibodies has been approved in fragile populations, including kidney transplant recipients, who are at risk of developing severe COVID-19. Sotrovimab is the only currently available anti-SARS-CoV-2 neutralizing monoclonal antibody with activity against the new Omicron variant of concern. While sotrovimab has been approved in adolescents and adults, studies regarding its efficacy and safety in children aged less than 12 years old and weighing less than 40 kg are still lacking. Here, we report a first case of a child, who was treated early with sotrovimab after a kidney transplant. CASE REPORT: At the end of January 2022, a 11-year-old male child underwent a deceased-donor kidney transplant and became infected with SARS-CoV-2 during the first day after surgery. Due to the increased risk of developing severe COVID-19, based on the predominance of Omicron and the patient's renal function, the child was treated with sotrovimab. The clinical course was successful and no adverse reactions were reported. CONCLUSIONS: For the first time, we report the well-tolerated use of sotrovimab in children under 12 years old. As the pandemic affects children across the globe, urgent data on sotrovimab dosing in children with a higher risk of developing severe COVID-19 are needed.

Monoclonal antibody therapeutics for infectious diseases: Beyond normal human immunoglobulin.

Antibody therapy is effective for treating infectious diseases. Due to the coronavirus disease 2019 (COVID-19) pandemic and the rise of drug-resistant bacteria, rapid development of neutralizing monoclonal antibodies (mAbs) to treat infectious diseases is urgently needed. Using a therapeutic human mAb with the lowest immunogenicity is recommended, because chimera and humanized mAbs are occasionally immunogenic. In order to directly obtain naïve human mAbs, there are three methods: phage display, B cell receptor (BCR) cDNA sequencing of a single cell, and antibody-encoding gene and amino acid sequencing of immortalized cells using memory B cells, which are isolated from human peripheral blood mononuclear cells of healthy, vaccinated, infected, or recovered individuals. After screening against the antigen and performing neutralization assays, a human neutralizing mAb is constructed from the antibody-encoding DNA sequences of these memory B cells. This review describes examples of obtaining human neutralizing mAbs against various infectious diseases using these methods. However, a few of these mAbs have been approved for therapy. Therefore, antigen characterization and evaluation of neutralization activity in vitro and in vivo are indispensable for the development of therapeutic mAbs. These results will accelerate the development of antibody drug as therapeutic agents.

VH3-53/66-Class RBD-Specific Human Monoclonal Antibody iB20 Displays Cross-Neutralizing Activity against Emerging SARS-CoV-2 Lineages.

Immune evasion of SARS-CoV-2 undermines current strategies tocounteract the pandemic, with the efficacy of therapeutic virus-neutralizing monoclonal antibodies (nAbs) being affected the most. In this work, we asked whether two previously identified human cross-neutralizing nAbs, iB14 (class VH1-58) and iB20 (class VH3-53/66), are capable of neutralizing the recently emerged Omicron (BA.1) variant. Both nAbs were found to bind the Omicron RBD with a nanomolar affinity, yet they displayed contrasting functional features. When tested against Omicron, the neutralizing activity of iB14 was reduced 50-fold, whereas iB20 displayed a surprising increase in activity. Thus, iB20 is a unique representative of the VH3-53/66-class of nAbs in terms of breadth of neutralization, which establishes it as a candidate for COVID-19 therapy and prophylactics.

REGN-COV2 antibody cocktail in patients with SARS-CoV-2: Observational study from a single institution in Japan.

INTRODUCTION: A new treatment for coronavirus disease (COVID-19), REGN-COV2, a cocktail consisting of two neutralizing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been approved for patients at a risk of developing more severe disease. METHODS: We retrospectively reviewed patients recently diagnosed with COVID-19 with risk factors for severe infection, who were treated with the REGN-COV2 antibody cocktail between July and September 2021. The REGN-COV2 antibody cocktail was administered to patients within 7 days of disease onset, with an oxygen saturation of >93%, and with at least one comorbidity. We investigated the percentage of patients with COVID-19-related hospitalization or death, the duration of symptoms after treatment, and the adverse effects of treatment. RESULTS: A total of 108 patients were reviewed. Of them, 64% were aged ≥50 years, 31% had obesity, 36% had hypertension, and 18% had diabetes. In addition, 49% had multiple risk factors for severe COVID-19. Overall, 12 patients (11%) needed COVID-19-related hospitalization. No adverse effects of treatment were observed. CONCLUSIONS: This study shows that treatment with the REGN-COV2 antibody cocktail is safe and beneficial in patients at a risk of developing severe COVID-19.

A brief overview about the latest news on SARS-CoV-2 therapeutic management

Loads of medications and vaccines are under investigation to prevent and heal coronavirus disease 2019 (COVID-19), which is putting a strain on healthcare systems worldwide. Among them, therapy with neutralizing monoclonal antibodies (nAbs) seems to be very promising in halting the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for the illness and in providing the patients with passive immunity. NAbs are designed to mimic the body’s natural immune response. Coronavirus infection is mediated by the interplay between the viral spike and the tissue angiotensin-converting enzyme 2 (ACE 2) receptor found on the apical surface of numerous cell types. However, nAbs are capable of blocking this interaction. They bind to the spike protein, thus impeding SARS-CoV-2 to enter human cells and tagging it for destruction. NAbs can be crucial in preventing COVID-19 from progressing to a severe form, and potentially are a prophylaxis option to subjects who have been exposed to SARS-CoV-2, while still waiting to get a vaccine. This mini review provides the readers with an overview about what is already known and what is new about the use of these agents. © 2021, Research Trends (P) LTD.. All rights reserved.

Murine monoclonal antibodies against RBD of the SARS-CoV-2 spike protein as useful analytical tools for subunit vaccine development and clinical trials.

COVID-19 pandemic poses a serious threat to human health; it has completely disrupted global stability, making vaccine development an important goal to achieve. Monoclonal antibodies play an important role in subunit vaccines strategies. In this work, nine murine MAbs against the RBD of the SARS-CoV-2 spike protein were obtained by hybridoma technology. Characterization of purified antibodies demonstrated that five of them have affinities in the order of 108 L/mol. Six MAbs showed specific recognition of different recombinant RBD-S antigens in solution. Studies of the additivity index of anti-RBD antibodies, by using a novel procedure to determine the additivity cut point, showed recognition of at least five different epitopes. The MAbs CBSSRBD-S.11 and CBSSRBD-S.8 revealed significant neutralizing capacity against SARS-CoV-2 in an ACE2-RBD binding inhibition assay (IC50 = 85.5pM and IC50 = 122.7pM, respectively) and in a virus neutralizing test with intact SARS-CoV-2 (VN50 = 0.552 nM and VN50 = 4.854 nM, respectively) when D614G strain was used to infect Vero cells. Also CBSSRBD-S.11 neutralized the SARS-CoV-2 strains Alpha and Beta: VN50 = 0.707 nM and VN50 = 0.132 nM, respectively. The high affinity CBSSRBD-S.8 and CBSSRBD-S.7 recognized different epitopes, so they are suitable for the development of a sandwich ELISA to quantitate RBD-S recombinant antigens in biomanufacturing processes, as well as in pharmacokinetic studies in clinical and preclinical trials.

Isolation and Characterization of Mouse Monoclonal Antibodies That Neutralize SARS-CoV-2 and Its Variants of Concern Alpha, Beta, Gamma and Delta by Binding Conformational Epitopes of Glycosylated RBD With High Potency.

Antibodies targeting Receptor Binding Domain (RBD) of SARS-CoV-2 have been suggested to account for the majority of neutralizing activity in COVID-19 convalescent sera and several neutralizing antibodies (nAbs) have been isolated, characterized and proposed as emergency therapeutics in the form of monoclonal antibodies (mAbs). However, SARS-CoV-2 variants are rapidly spreading worldwide from the sites of initial identification. The variants of concern (VOC) B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma) and B.1.167.2 (Delta) showed mutations in the SARS-CoV-2 spike protein potentially able to cause escape from nAb responses with a consequent reduction of efficacy of vaccines and mAbs-based therapy. We produced the recombinant RBD (rRBD) of SARS-CoV-2 spike glycoprotein from the Wuhan-Hu 1 reference sequence in a mammalian system, for mice immunization to isolate new mAbs with neutralizing activity. Here we describe four mAbs that were able to bind the rRBD in Enzyme-Linked Immunosorbent Assay and the transmembrane full-length spike protein expressed in HEK293T cells by flow cytometry assay. Moreover, the mAbs recognized the RBD in supernatants of SARS-CoV-2 infected VERO E6 cells by Western Blot under non-reducing condition or in supernatants of cells infected with lentivirus pseudotyped for spike protein, by immunoprecipitation assay. Three out of four mAbs lost their binding efficiency to completely N-deglycosylated rRBD and none was able to bind the same recombinant protein expressed in Escherichia coli, suggesting that the epitopes recognized by three mAbs are generated by the conformational structure of the glycosylated native protein. Of particular relevance, three mAbs were able to inhibit Wuhan SARS-CoV-2 infection of VERO E6 cells in a plaque-reduction neutralization test and the Wuhan SARS-CoV-2 as well as the Alpha, Beta, Gamma and Delta VOC in a pseudoviruses-based neutralization test. These mAbs represent important additional tools for diagnosis and therapy of COVID-19 and may contribute to the understanding of the functional structure of SARS-CoV-2 RBD.

Influence of treatment with neutralizing monoclonal antibodies on the SARS-CoV-2 nasopharyngeal load and quasispecies.

OBJECTIVES: To evaluate the impact of neutralizing monoclonal antibody (mAb) treatment and to determine whether the selective pressure of mAbs could facilitate the proliferation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with spike protein mutations that might attenuate mAb effectiveness. PATIENTS AND METHODS: We evaluated the impact of mAbs on the nasopharyngeal (NP) viral load and virus quasispecies of mAb-treated patients using single-molecule real-time sequencing. The mAbs used were: Bamlanivimab alone (four patients), Bamlanivimab/Etesevimab (23 patients) and Casirivimab/Imdevimab (five patients). RESULTS: The NP SARS-CoV-2 viral load of mAb-treated patients decreased from 8.2 log10 copies/mL before administration to 4.3 log10 copies/mL 7 days after administration. Five immunocompromised patients given Bamlanivimab/Etesevimab were found to have mAb activity-reducing spike mutations. Two patients harboured SARS-CoV-2 variants with a Q493R spike mutation 7 days after administration, as did a third patient 14 days after administration. The fourth patient harboured a variant with a Q493K spike mutation 7 days post-treatment, and the fifth patient had a variant with a E484K spike mutation on day 21. The emergence of the spike mutation was accompanied by stabilization or rebound of the NP viral load in three of five patients. CONCLUSION: Two-mAb therapy can drive the selection of resistant SARS-CoV-2 variants in immunocompromised patients. Patients given mAbs should be closely monitored and measures to limit virus spread should be reinforced.

Antibody Response against SARS-CoV-2 Infection: Implications for Diagnosis, Treatment and Vaccine Development.

Many recent studies have reported the onset of a robust antibody response to SARS-CoV-2 infection and highlighted produced antibodies' specific qualitative and quantitative aspects, relevant for developing antibody-based diagnostic and therapeutic options. In this review, firstly we will report main information acquired so far regarding the humoral response to COVID-19; we will concentrate, in particular, upon the observed levels and the kinetics, the specificity spectrum and the neutralizing potential of antibodies produced in infected patients. We will then discuss the implication of humoral response's characteristics in the development and correct use of serologic tests, as well as the efficacy and safety of convalescent plasma therapy and of neutralizing monoclonal antibodies for treating infected patients and preventing new infections. An update of the list of newly isolated specific neutralizing antibodies and suggestions for vaccine evaluation and development will be also provided.

Identification of SARS-CoV RBD-targeting monoclonal antibodies with cross-reactive or neutralizing activity against SARS-CoV-2.

SARS-CoV-2-caused COVID-19 cases are growing globally, calling for developing effective therapeutics to control the current pandemic. SARS-CoV-2 and SARS-CoV recognize angiotensin-converting enzyme 2 (ACE2) receptor via the receptor-binding domain (RBD). Here, we identified six SARS-CoV RBD-specific neutralizing monoclonal antibodies (nAbs) that cross-reacted with SARS-CoV-2 RBD, two of which, 18F3 and 7B11, neutralized SARS-CoV-2 infection. 18F3 recognized conserved epitopes on SARS-CoV and SARS-CoV-2 RBDs, whereas 7B11 recognized epitopes on SARS-CoV RBD not fully conserved in SARS-CoV-2 RBD. The 18F3-recognizing epitopes on RBD did not overlap with the ACE2-binding sites, whereas those recognized by 7B11 were close to the ACE2-binding sites, explaining why 7B11 could, but 18F3 could not, block SARS-CoV or SARS-CoV-2 RBD binding to ACE2 receptor. Our study provides an alternative approach to prevent SARS-CoV-2 infection using anti-SARS-CoV nAbs.