Neutralizing Monoclonal Antibodies Research Articles

MO659: First Experience of Bamlanivimab for Covid-19 Positive Haemodialysis Patients: A Case-Control Study

BACKGROUND AND AIMSThe previous study showed a higher prevalence of coronavirus (COVID-19) in end-stage renal disease (ESRD) patients than in the general population (3.1% versus 0.1%). The presence of COVID-19 infection significantly increased the mortality rate of patients on dialysis compared to non-COVID patients (20.2% versus 0.2%). To date, no clear guidelines exist for the management of COVID-19 in renal patients. Bamlanivimab is a potent neutralizing monoclonal antibody that blocks severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) attachment and entry into human cells, which could potentially lead to therapeutic benefit. To our knowledge, this is the first study to use bamlanivimab in COVID-19+ haemodialysis (HD) patients with the aim to determine the effect of bamlanivimab on the mortality of these patients.METHODWe conducted a retrospective case-control study across a single HD centre of non-hospitalized HD patients, with documented positive SARS-CoV-2 testing. We analysed the period from October 1 to November 14 2021, in which COVID-19+ patients were dialyzed in our institution. Cases were defined as HD patients who received bamlanivimab and controls were patients who did not receive bamlanivimab. Descriptive statistics, including chi-squared and Mann–Whitney U test, were performed. We used multinomial logistic regression to find the independent relationship between bamlanivimab use, disease severity, coronary artery disease (CAD), heart failure and 1-month mortality risk.RESULTSPatients who received bamlanivimab frequently had the chronic obstructive pulmonary disease (COPD) than those in the control group. There were no significant differences between groups in any of the other parameters assessed (Table 1). Besides higher baseline ferritin levels in the control group, no other significant differences in biochemical markers were found between examined groups (Table 2). Over a 1-month follow-up, one patient (7.7%) died in the bamlinivimab group, while 8 patients (44.4%) died in the control group. Multinomial logistic regression revealed that no bamlanivimab treatment was given. CAD and disease severity increased the risks of mortality 39.1 times (P = 0.12), 81.7 times (P = 0.08) and 99.9 times (P = 0.04), respectively.CONCLUSIONIn COVID-19+ HD patients, bamlanivimab has been a safe and effective treatment method, lowering mortality although not statistically significant. We also discovered that having a more severe clinical presentation at baseline, as well as having a CAD, was related to a greater risk of mortality. Our findings imply that larger, more conclusive clinical studies of bamlanivimab in HD patients with COVID 19 should be conducted.Table 1.Baseline characteristics of 31 COVID-19 and haemodialysis patientsCharacteristicsBamlanivimab therapy (n = 13)No bamlanivimab (n = 18) P-valueMales, n %69.267.71.000Mean age, years62.2 ± 11.365.9 ± 15.8.476BMI25.9 ± 3.624.2 ± 2.8.167Diabetes (main disease or co-morbidity), n %23.122.2.955Arteriovenous fistula, n %100.017/94.41.000Dialysis vintage, monthsMedian (IQR)60 (25.5–134.0)45 (8.5–100).281 COPD (yes), n % 38.5 0.0 .008 Stroke (yes), n %7.70.0.419CAD (yes), n %30.838.9.468Covid-19 vaccine (yes), n %69.283.3.354Duration of symptoms before bamlanivimab administration, median days (IQR)/3 (2.5–4.5)/Table 2.Symptoms, signs and laboratory parameters of COVID-19 in 31 haemodialysis patients (yes), %Bamlanivimab Therapy (n = 13)No Bamlanivimab (n = 18) P-valueCough38.544.41.000Fever61.572.2.701Fatigue30.833.31.000Rhinorrhea0.05.61.000Sore throat7.716.7.621Diarrhoea7.711.11.000Nausea15.45.6.361Vomiting15.40.0.168Disease Severity, n %AsymptomaticMildModerateSevere7.753.830.87.711.133.333.322.2.604Nutri-CoV score, %Low riskModerate riskHigh riskVery high risk0.061.530.87.711.133.327.827.8.224C-reactive protein, mg/L, median (IQR)43.0 (6.5–155.5)43.0 (22.8–63.8).880 Ferritin, ng/mL median (IQR) 528.5 (215.6–718.5) 840 (544.7–1576) .020 D dimer, mg/L1.14 ± 0.871.34 ± 0.99.523

Broadly neutralizing antibodies against Omicron-included SARS-CoV-2 variants induced by vaccination

The SARS-CoV-2 Omicron variant shows substantial resistance to neutralization by infection- and vaccination-induced antibodies, highlighting the demands for research on the continuing discovery of broadly neutralizing antibodies (bnAbs). Here, we developed a panel of bnAbs against Omicron and other variants of concern (VOCs) elicited by vaccination of adenovirus-vectored COVID-19 vaccine (Ad5-nCoV). We also investigated the human longitudinal antibody responses following vaccination and demonstrated how the bnAbs evolved over time. A monoclonal antibody (mAb), named ZWD12, exhibited potent and broad neutralization against SARS-CoV-2 variants Alpha, Beta, Gamma, Kappa, Delta, and Omicron by blocking the spike protein binding to the angiotensin-converting enzyme 2 (ACE2) and provided complete protection in the challenged prophylactic and therapeutic K18-hACE2 transgenic mouse model. We defined the ZWD12 epitope by determining its structure in complex with the spike (S) protein via cryo-electron microscopy. This study affords the potential to develop broadly therapeutic mAb drugs and suggests that the RBD epitope bound by ZWD12 is a rational target for the design of a broad spectrum of vaccines.

Characterization of a universal neutralizing monoclonal antibody against Glaesserella parasuis CdtB

Glaesserella parasuis is the etiological agent of Glässer's disease. Although present as a symbiotic bacterium in the respiratory tract of healthy pigs, G. parasuis invades piglets under stress conditions and causes severe systemic infection characterized by fibrinous polyserositis, polyarthritis, and meningitis, which caused high mortality in weaned and nursery herds. Further, the lack of cross-protection against the various serotypes of G. parasuis is a serious concern for the swine industry. Cytolethal distending toxin (CDT) is essential for the pathogenicity of G. parasuis and is a conserved virulence factor. CdtB is the active subunit of CDT, causing DNA double-strand breaks in eukaryotic cells, leading to irreversible cell cycle arrest and apoptosis. However, the immunogenicity and immunogenic domain of G. parasuis CdtB have not been investigated. In this study, monoclonal antibodies (mAbs) against G. parasuis CdtB were screened. One mAb, 4F10, was characterized and found to specifically recognize G. parasuis strains of all serotypes, including non-typeable strains, without showing any reactivity with other swine bacterial pathogens. Additionally, 4F10 exhibited neutralizing activity that restrained the cytotoxicity caused by CdtB. Moreover, the core unit of the epitope 84GVGFPIDEYVWNLGTRSRPN103 recognized by 4F10 was identified. The mAb-4F10 characterized herein provides a candidate for the further investigation of the pathogenic and immunogenic functions of CdtB in G. parasuis and could facilitate future serological diagnosis, prevention, and control of this disease.

Intranasal Lentiviral Vector-Mediated Antibody Delivery Confers Reduction of SARS-CoV-2 Infection in Elderly and Immunocompromised Mice.

Vaccines for COVID-19 are now a crucial public health need, but the degree of protection provided by conventional vaccinations for individuals with compromised immune systems is unclear. The use of viral vectors to express neutralizing monoclonal antibodies (mAbs) in the lung is an alternative approach that does not wholly depend on individuals having intact immune systems and responses. Here, we identified an anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) monoclonal antibody, NC0321, which can efficiently neutralize a range of SARS-CoV-2 variants, including alpha, beta, delta, and eta. Both prophylactic and therapeutic NC0321 treatments effectively protected mice from SARS-CoV-2 infection. Notably, we adopted viral vector-mediated delivery of NC0321 IgG1 as an attractive approach to prevent SARS-CoV-2 infection. The NC0321 IgG1 expression in the proximal airway, expressed by a single direct in-vivo intranasal (I.N.) administration of a self-inactivating and recombinant lentiviral vector (rSIV.F/HN-NC0321), can protect young, elderly, and immunocompromised mice against mouse-adapted SARS-CoV-2 surrogate challenge. Long-term monitoring indicated that rSIV.F/HN-NC0321 mediated robust IgG expression throughout the airway of young and SCID mice, importantly, no statistical difference in the NC0321 expression between young and SCID mice was observed. A single I.N. dose of rSIV.F/HN-NC0321 30 or 180 days prior to SARS-CoV-2 challenge significantly reduced lung SARS-CoV-2 titers in an Ad5-hACE2-transduced mouse model, reconfirming that this vectored immunoprophylaxis strategy could be useful, especially for those individuals who cannot gain effective immunity from existing vaccines, and could potentially prevent clinical sequelae.

Structural definition of a pan-sarbecovirus neutralizing epitope on the spike S2 subunit

Three betacoronaviruses have crossed the species barrier and established human-to-human transmission causing significant morbidity and mortality in the past 20 years. The most current and widespread of these is SARS-CoV-2. The identification of CoVs with zoonotic potential in animal reservoirs suggests that additional outbreaks could occur. Monoclonal antibodies targeting conserved neutralizing epitopes on diverse CoVs can form the basis for prophylaxis and therapeutic treatments and enable the design of vaccines aimed at providing pan-CoV protection. We previously identified a neutralizing monoclonal antibody, CV3-25 that binds to the SARS-CoV-2 spike, neutralizes the SARS-CoV-2 Beta variant comparably to the ancestral Wuhan Hu-1 strain, cross neutralizes SARS-CoV-1 and binds to recombinant proteins derived from the spike-ectodomains of HCoV-OC43 and HCoV-HKU1. Here, we show that the neutralizing activity of CV3-25 is maintained against the Alpha, Delta, Gamma and Omicron variants of concern as well as a SARS-CoV-like bat coronavirus with zoonotic potential by binding to a conserved linear peptide in the stem-helix region. Negative stain electron microscopy and a 1.74 Å crystal structure of a CV3-25/peptide complex demonstrates that CV3-25 binds to the base of the stem helix at the HR2 boundary to an epitope that is distinct from other stem-helix directed neutralizing mAbs.

Antigenicity comparison of SARS-CoV-2 Omicron sublineages with other variants contained multiple mutations in RBD.

The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants, particularly those with multiple mutations in receptor‐binding domain (RBD), pose a critical challenge to the efficacy of coronavirus disease 2019 (COVID‐19) vaccines and therapeutic neutralizing monoclonal antibodies (mAbs). Omicron sublineages BA.1, BA.2, BA.3, as well as the recent emergence of C.1.2, B.1.630, B.1.640.1, and B.1.640.2, have multiple mutations in RBD and may lead to severe neutralizing antibody evasion. It is urgent to evaluate the antigenic change of the above seven variants against mAbs and sera from guinea pigs immunized with variants of concern (VOCs) (Alpha, Beta, Gamma, Delta, Omicron) and variants of interest (VOIs) (Lambda, Mu) immunogens. Only seven out of the 24 mAbs showed no reduction in neutralizing activity against BA.1, BA.2, and BA.3. However, among these seven mAbs, the neutralization activity of XGv337 and XGv338 against C.1.2, B.1.630, B.1.640.1, and B.1.640.2 were decreased. Therefore, only five neutralizing mAbs showed no significant change against these seven variants. Using VOCs and VOIs as immunogens, we found that the antigenicity of variants could be divided into three clusters, and each cluster showed similar antigenicity to different immunogens. Among them, D614G, B.1.640.1, and B.1.630 formed a cluster, C.1.2 and B.1.640.2 formed a cluster, and BA.1, BA.2, and BA.3 formed a cluster.

Antiviral Cell Products against COVID-19: Learning Lessons from Previous Research in Anti-Infective Cell-Based Agents.

COVID-19 is a real challenge for the protective immunity. Some people do not respond to vaccination by acquiring an appropriate immunological memory. The risk groups for this particular infection such as the elderly and people with compromised immunity (cancer patients, pregnant women, etc.) have the most serious problems in developing an adequate immune response. Therefore, dendritic cell (DC) vaccines that are loaded ex vivo with SARS-CoV-2 antigens in the optimal conditions are promising for immunization. Lymphocyte effector cells with chimeric antigen receptor (CAR lymphocytes) are currently used mainly as anti-tumor treatment. Before 2020, few studies on the antiviral CAR lymphocytes were reported, but since the outbreak of SARS-CoV-2 the number of such studies has increased. The basis for CARs against SARS-CoV-2 were several virus-specific neutralizing monoclonal antibodies. We propose a similar, but basically novel and more universal approach. The extracellular domain of the immunoglobulin G receptors will be used as the CAR receptor domain. The specificity of the CAR will be determined by the antibodies, which it has bound. Therefore, such CAR lymphocytes are highly universal and have functional activity against any infectious agents that have protective antibodies binding to a foreign surface antigen on the infected cells.

Neutralizing antibodies protect mice against Venezuelan equine encephalitis virus aerosol challenge.

Venezuelan equine encephalitis virus (VEEV) remains a risk for epidemic emergence or use as an aerosolized bioweapon. To develop possible countermeasures, we isolated VEEV-specific neutralizing monoclonal antibodies (mAbs) from mice and a human immunized with attenuated VEEV strains. Functional assays and epitope mapping established that potently inhibitory anti-VEEV mAbs bind distinct antigenic sites in the A or B domains of the E2 glycoprotein and block multiple steps in the viral replication cycle including attachment, fusion, and egress. A 3.2-Å cryo-electron microscopy reconstruction of VEEV virus-like particles bound by a human Fab suggests that antibody engagement of the B domain may result in cross-linking of neighboring spikes to prevent conformational requirements for viral fusion. Prophylaxis or postexposure therapy with these mAbs protected mice against lethal aerosol challenge with VEEV. Our study defines functional and structural mechanisms of mAb protection and suggests that multiple antigenic determinants on VEEV can be targeted for vaccine or antibody-based therapeutic development.

Broad antiviral peptides against PRRSV based on novel linear epitopes on porcine CD163

PRRSV causes major economic losses to swine industry world-wide, which requires innovative antiviral agents. Porcine scavenger receptor CD163 has been identified as an essential fusion receptor for Porcine reproductive and respiratory Syndrome Virus (PRRSV) infection. In this study, novel antiviral peptides from pCD163 against PRRSV were developed based on broad neutralizing monoclonal antibodies. SRCR-5-9 of pCD163 from baculovirus efficiently binds to PRRSVs of lineage 8 and lineage 1, blocking infection in PAMs. A batch of monoclonal antibodies targeting SRCR-5-9 were generated and characterized. 8H2 and 4H7 block PRRSV infection by the disruption in viral attachment to PAMs. Virus titer reduced 100–1000 folds in average and the virus copy number decreased about 104 folds with these antibodies. Linear epitopes of 8H2 and 4H7 were individually localized in SRCR6 (1-30 aa) and PSTI(1-15aa) of pCD163. Mutations of SRCR6 NI1718KT and PST SS1314AA abolished the recognition of 8H2 and 4H7 to the corresponding region individually. Peptides derived from the linear epitopes displayed a broad inhibitory effect on PRRSVs of different lineages in a dose-dependent manner and further modulated PRRSV-related NF-κB pathway. In conclusion, these findings deepen the understanding in the interaction between PRRSV and pCD163 receptor and provide alternative universal antiviral strategies against PRRSV.

Introduction of a Capillary Gel Electrophoresis-Based Workflow for Biotherapeutics Characterization: Size, Charge, and N-Glycosylation Variant Analysis of Bamlanivimab, an Anti-SARS-CoV-2 Product.

Coronavirus Disease 2019 (COVID-19) is a major public health problem worldwide with 5–10% hospitalization and 2–3% global mortality rates at the time of this publication. The disease is caused by a betacoronavirus called Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The receptor-binding domain (RBD) of the Spike protein expressed on the surface of the virus plays a key role in the viral entry into the host cell via the angiotensin-converting enzyme 2 receptor. Neutralizing monoclonal antibodies having the RBD as a target have the ability to inhibit angiotensin-converting enzyme 2 (ACE2) receptor binding, therefore, prevent SARS-CoV-2 infection, represent a promising pharmacological strategy. Bamlanivimab is the first anti-spike neutralizing monoclonal antibody, which got an emergency use authorization from the FDA for COVID-19 treatment. Albeit, bamlanivimab is primarily a neutralizing mAb, some of its effector function related activity was also emphasized. The effector function of antibody therapeutics is greatly affected by their N-linked carbohydrates at the conserved Fc region, possibly influenced by the manufacturing process. Various capillary gel electrophoresis methods are widely accepted in the biopharmaceutical industry for the characterization of therapeutic antibodies. In this paper we introduce a capillary gel electrophoresis based workflow for 1) size heterogeneity analysis to determine the presence/absence of the non-glycosylated heavy chain (NGHC) fragment (SDS-CGE); 2) capillary gel isoelectric focusing for possible N-glycosylation mediated charge heterogeneity determination, e.g., for excess sialylation and finally, 3) capillary gel electrophoresis for N-glycosylation profiling and sequencing. Our results have shown the presence of negligible amount of non-glycosylated heavy chain (NGHC) while 25% acidic charge variants were detected. Comprehensive N-glycosylation characterization revealed the occurrence of approximately 8.2% core-afucosylated complex and 17% galactosylated N-linked oligosaccharides, suggesting the possible existence of antibody dependent cell mediated cytotoxicity (ADCC) effector function in addition to the generally considered neutralizing effect of this particular therapeutic antibody molecule.

Antibody evasion properties of SARS-CoV-2 Omicron sublineages

The identification of the Omicron (B.1.1.529.1 or BA.1) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Botswana in November 20211 immediately caused concern owing to the number of alterations in the spike glycoprotein that could lead to antibody evasion. We2 and others3–6 recently reported results confirming such a concern. Continuing surveillance of the evolution of Omicron has since revealed the rise in prevalence of two sublineages, BA.1 with an R346K alteration (BA.1+R346K, also known as BA.1.1) and B.1.1.529.2 (BA.2), with the latter containing 8 unique spike alterations and lacking 13 spike alterations found in BA.1. Here we extended our studies to include antigenic characterization of these new sublineages. Polyclonal sera from patients infected by wild-type SARS-CoV-2 or recipients of current mRNA vaccines showed a substantial loss in neutralizing activity against both BA.1+R346K and BA.2, with drops comparable to that already reported for BA.1 (refs. 2,3,5,6). These findings indicate that these three sublineages of Omicron are antigenically equidistant from the wild-type SARS-CoV-2 and thus similarly threaten the efficacies of current vaccines. BA.2 also exhibited marked resistance to 17 of 19 neutralizing monoclonal antibodies tested, including S309 (sotrovimab)7, which had retained appreciable activity against BA.1 and BA.1+R346K (refs. 2–4,6). This finding shows that no authorized monoclonal antibody therapy could adequately cover all sublineages of the Omicron variant, except for the recently authorized LY-CoV1404 (bebtelovimab).

Lowering blood cholesterol does not affect neuroinflammation in experimental autoimmune encephalomyelitis

BackgroundMultiple sclerosis (MS) is a chronic disabling disease of the central nervous system (CNS) commonly affecting young adults. There is increasing evidence that environmental factors are important in the development and course of MS. The metabolic syndrome (MetS) which comprises dyslipidemia has been associated with a worse outcome in MS disease. Furthermore, the lipid-lowering drug class of statins has been proposed to improve MS disease course. However, cholesterol is also rate-limiting for myelin biogenesis and promotes remyelination in MS animal models. Thus, the impact of circulating blood cholesterol levels during the disease remains debated and controversial.MethodsWe assessed the role of circulating cholesterol on the murine model of MS, the experimental autoimmune encephalomyelitis (EAE) disease using two different approaches: (1) the mouse model of familial hypercholesterolemia induced by low-density lipoprotein receptor (LDLr) deficiency, and (2) the use of the monoclonal anti-PCSK9 neutralizing antibody alirocumab, which reduces LDLr degradation and consequently lowers blood levels of cholesterol.ResultsElevated blood cholesterol levels induced by LDLr deficiency did not worsen clinical symptoms of mice during EAE. In addition, we observed that the anti-PCSK9 antibody alirocumab did not influence EAE disease course, nor modulate the immune response in EAE.ConclusionsThese findings suggest that blood cholesterol level has no direct role in neuro-inflammatory diseases and that the previously shown protective effects of statins in MS are not related to circulating cholesterol.

Altered TMPRSS2 usage by SARS-CoV-2 Omicron impacts infectivity and fusogenicity

The SARS-CoV-2 Omicron BA.1 variant emerged in 20211 and has multiple mutations in its spike protein2. Here we show that the spike protein of Omicron has a higher affinity for ACE2 compared with Delta, and a marked change in its antigenicity increases Omicron’s evasion of therapeutic monoclonal and vaccine-elicited polyclonal neutralizing antibodies after two doses. mRNA vaccination as a third vaccine dose rescues and broadens neutralization. Importantly, the antiviral drugs remdesivir and molnupiravir retain efficacy against Omicron BA.1. Replication was similar for Omicron and Delta virus isolates in human nasal epithelial cultures. However, in lung cells and gut cells, Omicron demonstrated lower replication. Omicron spike protein was less efficiently cleaved compared with Delta. The differences in replication were mapped to the entry efficiency of the virus on the basis of spike-pseudotyped virus assays. The defect in entry of Omicron pseudotyped virus to specific cell types effectively correlated with higher cellular RNA expression of TMPRSS2, and deletion of TMPRSS2 affected Delta entry to a greater extent than Omicron. Furthermore, drug inhibitors targeting specific entry pathways3 demonstrated that the Omicron spike inefficiently uses the cellular protease TMPRSS2, which promotes cell entry through plasma membrane fusion, with greater dependency on cell entry through the endocytic pathway. Consistent with suboptimal S1/S2 cleavage and inability to use TMPRSS2, syncytium formation by the Omicron spike was substantially impaired compared with the Delta spike. The less efficient spike cleavage of Omicron at S1/S2 is associated with a shift in cellular tropism away from TMPRSS2-expressing cells, with implications for altered pathogenesis.

Anti–SARS-CoV-2 Monoclonal Antibodies for Early COVID-19

Background Anti–SARS-CoV-2 monoclonal antibodies have been shown to reduce severe COVID-19 in high-risk ambulatory patients. Methods This operations study at 3 affiliated centers conducted from November 23, 2020, to April 30, 2021, identified and treated patients meeting criteria for anti–SARS-CoV-2 monoclonal antibody therapy. The primary study outcome was treatment of qualifying patients. Secondary outcomes included infusion complications, hospitalization/death, and symptom resolution. Results Three hundred sixty-seven patients were treated during the study period. The mean patient age was 63 years (SD, 13.47 years). A total of 201 patients (55%) were male, 276 patients (75%) were White, 54 patients (15%) were African American, 10 patients (2.7%) were Asian, and 9 patients (2.4%) identified as Latino or Hispanic. Patients had a first positive direct SARS-CoV-2 test within 10 days of infusion and met high-risk criteria with 232 patients (63%) having more than 1 risk factor. Thirty-two patients (9%) had received at least 1 dose of SARS-CoV-2 vaccination. Four patients experienced an infusion reaction. Of 236 patients reporting time to symptom resolution, 172 patients (73%) were symptom free within 5 days of infusion. Twenty patients (5%) treated were hospitalized for COVID-19 within 30 days of infusion including 1 patient death from COVID-19. Conclusions Our study demonstrates that treatment with anti–SARS-CoV-2 neutralizing monoclonal antibodies is feasible in a high-resource health care setting. Infusion was well tolerated by the majority of patients, and there were no known infusion center SARS-CoV-2 exposures.

Growth, Antigenicity, and Immunogenicity of SARS-CoV-2 Spike Variants Revealed by a Live rVSV-SARS-CoV-2 Virus.

SARS-CoV-2 is an emerging coronavirus threatening human health and the economy worldwide. As an RNA virus, variants emerge during the pandemic and potentially influence the efficacy of the anti-viral drugs and vaccines. Eight spike variants harboring highly recurrent mutations were selected and introduced into a replication-competent recombinant VSV in place of the original G protein (rVSV-SARS-CoV-2). The resulting mutant viruses displayed similar growth curves in vitro as the wild-type virus and could be neutralized by sera from convalescent COVID-19 patients. Several variants, especially Beta strain, showed resistance to human neutralizing monoclonal antibodies targeting the receptor-binding domain (RBD). A single dose of rVSV-SARS-CoV-2 Beta variant could elicit enhanced and broad-spectrum neutralizing antibody responses in human ACE2 knock-in mice and golden Syrian hamsters, while other mutants generated antibody levels comparable to the wild-type. Therefore, our results will be of value to the development of next-generation vaccines and therapeutic antibodies.

Editorial: Current Status of Oral Antiviral Drug Treatments for SARS-CoV-2 Infection in Non-Hospitalized Patients

On 4th November 2021, the first oral antiviral drug for COVID-19, molnupiravir (Lagevrio®), received full regulatory approval from the Medicines and Healthcare Products Regulatory Agency (MHRA) in the UK. Molnupiravir is an orally bioavailable antiviral drug for use at home when a SARS-CoV-2 test is positive. On 22nd December 2022, the FDA granted emergency use authorization (EUA) for the oral antiviral drug, nirmatrelvir/ritonavir (Paxlovid®) for adults and children with mild and moderate COVID-19 at increased risk of progression to severe COVID-19. These regulatory drug approvals come at a crucial time when new variants of concern of the SARS-CoV-2 virus are spreading rapidly. Although the FDA approved remdesivir (Veklury®) on 22nd October 2020 for use in adults and children for the treatment of COVID-19 requiring hospitalization, its use has been limited by the requirement for intravenous administration in a healthcare facility. The four FDA-approved therapeutic neutralizing monoclonal antibodies, imdevimab, bamlanivimab, etesevimab, and casirivimab are costly and also require medically-supervised intravenous administration. The availability of effective, low-cost oral antiviral drugs available in a community setting that can be used at an early stage of SARS-CoV-2 infection is now a priority in controlling COVID-19. An increasing number of repurposed antiviral drugs are currently under investigation or in the early stages of regulatory approval. This Editorial aims to present an update on the current status of orally bioavailable antiviral drug treatments for SARS-CoV-2 infection.

Insights from computational analysis: how does the SARS-CoV-2 Delta (B.1.617.2) variant hijack ACE2 more effectively?

The SARS-CoV-2 Delta (B.1.617.2) variant was identified in India in October 2020, and it has quickly become the mainstream strain with strong toxicity and spread, posing great challenges to epidemic control. However, the molecular mechanism of its powerful infectivity remains unclear. It is meaningful to investigate the process of Delta variant's receptor-binding domain (RBD) binding to angiotensin-converting enzyme 2 (ACE2). Here, we performed three repeated molecular dynamics simulations for each system to avoid accidents, and the alanine scanning combined with the interaction entropy (ASIE) method was utilized to evaluate the binding free energy. Through the detailed energy and conformational analysis, the binding mechanism of the Delta variant was illustrated. The results showed that the existence of L452R and T478K mutations can trigger the effective hijacking of ACE2 by the Delta variant through the following three ways: (i) these two mutations can significantly enhance the electrostatic energy of the system by the introduction of two positively charged amino acids (Arg and Lys), thereby increasing the binding affinity of RBD and ACE2, (ii) the Loops 1, 3, and 4 in the receptor-binding motif (RBM) of RBD form a tighter conformation under the dominance of the T478K mutation, allowing ACE2 to be captured more effectively than the wild-type system, and (iii) these conformational changes lead to a more stable hydrogen bond in the Delta variant, which further ensures the stability of the binding. In addition, to explore the effect of mutations on the antibody, the key residues contributing to the changes in the binding ability of RBD in the Delta variant with the existing 42 neutralizing monoclonal antibodies (mAbs) have been preliminarily evaluated. The present study reveals the molecular mechanism for the increased infectivity of SARS-CoV-2 caused by mutations, and the key sites that cause antigenic changes were screened. It provides important theoretical insights for the development of novel targeted RBD drugs and antibodies.

Reduced sensitivity of the SARS-CoV-2 Lambda variant to monoclonal antibodies and neutralizing antibodies induced by infection and vaccination

ABSTRACT Severe acute respiratory syndrome coronavirus 2 variants have continued to emerge in diverse geographic locations with a temporal distribution. The Lambda variant containing multiple mutations in the spike protein, has thus far appeared mainly in South America. The variant harbours two mutations in the receptor binding domain, L452Q and F490S, which may change its infectivity and antigenicity to neutralizing antibodies. In this study, we constructed 10 pseudoviruses to study the Lambda variant and each individual amino acid mutation's effect on viral function, and used eight cell lines to study variant infectivity. In total, 12 monoclonal antibodies, 14 convalescent sera, and 23 immunized sera induced by mRNA vaccines, inactivated vaccine, and adenovirus type 5 vector vaccine were used to study the antigenicity of the Lambda variant. We found that compared with the D614G reference strain, Lambda demonstrated enhanced infectivity of Calu-3 and LLC-MK2 cells by 3.3-fold and 1.6-fold, respectively. Notably, the sensitivity of the Lambda variant to 5 of 12 neutralizing monoclonal antibodies, 9G11, AM180, R126, X593, and AbG3, was substantially diminished. Furthermore, convalescent- and vaccine-immunized sera showed on average 1.3–2.5-fold lower neutralizing titres against the Lambda variant. Single mutation analysis revealed that this reduction in neutralization was caused by L452Q and F490S mutations. Collectively, the reduced neutralization ability of the Lambda variant suggests that the efficacy of monoclonal antibodies and vaccines may be compromised during the current pandemic.

IL-6/STAT3 Is a Promising Therapeutic Target for Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a common malignant tumor of which the occurrence and development, the tumorigenicity of HCC is involving in multistep and multifactor interactions. Interleukin-6 (IL-6), a multifunctional inflammatory cytokine, has increased expression in HCC patients and is closely related to the occurrence of HCC and prognosis. IL-6 plays a role by binding to the IL-6 receptor (IL-6R) and then triggering the Janus kinase (JAK) associated with the receptor, stimulating phosphorylation and activating signal transducer and activator of transcription 3 (STAT3) to initiate downstream signals, participating in the processes of anti-apoptosis, angiogenesis, proliferation, invasion, metastasis, and drug resistance of cancer cells. IL-6/STAT3 signal axes elicit an immunosuppressive in tumor microenvironment, it is important to therapy HCC by blocking the IL-6/STAT3 signaling pathway. Recent, some inhibitors of IL-6/STAT3 have been development, such as S31-201 or IL-6 neutralizing monoclonal antibody (IL-6 mAb), Madindoline A (Inhibits the dimerization of IL-6/IL-6R/gpl30 trimeric complexes), C188-9 and Curcumin (Inhibits STAT3 phosphorylation), etc. for treatment of cancers. Overall, consideration of the IL-6/STAT3 signaling pathway, and its role in the carcinogenesis and progression of HCC will contribute to the development of potential drugs for targeting treatment of liver cancer.

522. Evaluation of Three COVID-19 Monoclonal Antibody Regimens in the Context of Rising B.1.526 Prevalence in New York City

BackgroundMonoclonal antibodies were given emergency use authorization (EUA) by the Food and Drug Administration for the treatment of high-risk, outpatient COVID-19 infection. In New York City (NYC), the emergence and rapid growth of the B.1.526 variant of concern (VOC) possessing the E484K mutation was first noted in February 2021. In-vitro studies subsequently confirmed attenuated monoclonal antibody neutralization against VOCs. At our institution, bamlanivimab (BAM) alone or with etesevimab (B/E) and casirivimab/imdevimab (C/I) were utilized at different phases of the pandemic. The objective of this study was to assess their comparative efficacies in a highly variant prevalent setting.MethodsThis retrospective analysis was conducted at an urban hospital in the Bronx, NY and evaluated adult monoclonal antibody recipients from any of our infusion sites. Patients initially received BAM but given the high prevalence of variants, treatment was transitioned to first B/E and then C/I exclusively. We compared BAM versus combination therapy as well as B/E versus C/I individually. The primary outcome was all-cause hospital admission within 30 days post infusion.ResultsFrom February 1 to March 7, 2021, 358 patients received BAM and from March 17 to May 9, 2021, 86 and 179 patients received B/E and C/I, respectively. Compared to any combination infusion, patients who received BAM were significantly older, more likely to possess ≥ 2 qualifying EUA criteria, and less likely to be vaccinated for COVID-19 prior to infusion (Table 1). Following B/E and C/I, 4.5% of patients were admitted versus 10.1% for BAM, p=0.011. There were no significant differences in admission between B/E and C/I recipients, p=0.485. After excluding fully vaccinated patients (n=14) and adjusting for age and ≥ 2 EUA criteria, combination therapy remained associated with decreased odds of hospitalization compared to BAM (odds ratio, 0.48; 95% confidence interval, 0.24-0.94). ConclusionCombination therapy may be associated with fewer hospital admissions following infusion, although there were no statistically significant differences between the individual combination infusions. We suggest similar studies be conducted by other sites to understand the clinical impact of local SARS-CoV-2 variants on antibody efficacy.Disclosures Yi Guo, PharmD, BCIDP, Merck (Research Grant or Support) Kelsie Cowman, MPH, Merck (Research Grant or Support) Priya Nori, MD, Merck (Grant/Research Support) Priya Nori, MD, Nothing to disclose