Therapeutic anti-IgE Antibody Research Articles

Biological Effects and Clinical Application of the Anti-Immunoglobulin E Antibody

Background: Immunoglobulin E (IgE) plays a pivotal role in the pathogenesis of allergic diseases by engaging with FcεRI and FcεRII receptors, triggering allergic responses. The development of anti-IgE antibodies, such as omalizumab, has introduced a targeted approach to allergy treatment by neutralizing free IgE and dampening the allergic cascade. Summary: This review synthesizes the current understanding of IgE’s role in allergic diseases and evaluates the clinical utility of omalizumab. It specifically examines the biological mechanisms underpinning anti-IgE antibodies and their efficacy in treating moderate to severe asthma and chronic spontaneous urticaria (CSU). The paper also explores the potential of omalizumab in managing other allergic conditions and considers the long-term implications of anti-IgE therapy. Key Messages: By summarizing and elucidating the biological mechanisms and clinical applications of anti-IgE antibodies through a review of global literature from the past 5 years, this article aims to establish a theoretical foundation for developing innovative anti-allergic treatment strategies. Omalizumab has demonstrated efficacy in reducing IgE-mediated responses, offering improved clinical outcomes for patients with asthma and CSU, with promising potential in an array of allergic diseases. The long-term safety profile of anti-IgE medications remains an area of active investigation, underscoring the need for ongoing research to refine these therapies and expand their application in allergy management.

A Comparison of Natural and Therapeutic Anti-IgE Antibodies.

Immunoglobulin E (IgE) plays a critical role for the immune system, fighting against parasites, toxins, and cancer. However, when it reacts to allergens without proper regulation, it can cause allergic reactions, including anaphylaxis, through a process initiated by effector cells such as basophils and mast cells. These cells display IgE on their surface, bound to the high-affinity IgE receptor FcεRI. A cross-linking antigen then triggers degranulation and the release of inflammatory mediators from the cells. Therapeutic monoclonal anti-IgE antibodies such as omalizumab, disrupt this process and are used to manage IgE-related conditions such as severe allergic asthma and chronic spontaneous urticaria. Interestingly, naturally occurring anti-IgE autoantibodies circulate at surprisingly high levels in healthy humans and mice and may thus be instrumental in regulating IgE activity. Although many open questions remain, recent studies have shed new light on their role as IgE regulators and their mechanism of action. Here, we summarize the latest insights on natural anti-IgE autoantibodies, and we compare their functional features to therapeutic monoclonal anti-IgE autoantibodies.

Bispecific T-Cell Engagers Targeting Membrane-Bound IgE.

The increased incidence of allergies and asthma has sparked interest in IgE, the central player in the allergic response. Interaction with its high-affinity receptor FcεRI leads to sensitization and allergen presentation, extracellular membrane-proximal domain in membrane IgE can act as an antigen receptor on B cells, and the interaction with low-affinity IgE receptor CD23 additionally influences its homeostatic range. Therapeutic anti-IgE antibodies act by the inhibition of IgE functions by interfering with its receptor binding or by the obliteration of IgE-B cells, causing a reduction of serum IgE levels. Fusion proteins of antibody fragments that can act as bispecific T-cell engagers have proven very potent in eliciting cytotoxic T-lymphocyte-mediated killing. We have tested five anti-IgE Fc antibodies, recognizing different epitopes on the membrane-expressed IgE, for the ability to elicit specific T-cell activation when expressed as single-chain Fv fragments fused with anti-CD3ε single-chain antibody. All candidates could specifically stain the cell line, expressing the membrane-bound IgE-Fc and bind to CD3-positive Jurkat cells, and the specific activation of engineered CD3-overexpressing Jurkat cells and non-stimulated CD8-positive cells was demonstrated for 8D6- and ligelizumab-based bispecific antibodies. Thus, such anti-IgE antibodies have the potential to be developed into agents that reduce the serum IgE concentration by lowering the numbers of IgE-secreting cells.

Past, present, and future of anti-IgE biologics.

About 20years after the identification of immunoglobulin E (IgE) and its key role in allergic hypersensitivity reactions against normally harmless substances, scientists have started inventing strategies to block its pathophysiological activity in 1986. The initial concept of specific IgE targeting through the use of anti-IgE antibodies has gained a lot of momentum and within a few years independent research groups have reported successful generation of first murine monoclonal anti-IgE antibodies. Subsequent generation of optimized chimeric and humanized versions of these antibodies has paved the way for the development of therapeutic anti-IgE biologicals as we know them today. With omalizumab, there is currently still only one therapeutic anti-IgE antibody approved for the treatment of allergic conditions. Since its application is limited to the treatment of moderate-to-severe persistent asthma and chronic spontaneous urticaria, major efforts have been undertaken to develop alternative anti-IgE biologicals that could potentially be used in a broader spectrum of allergic diseases. Several new drug candidates have been generated and are currently assessed in pre-clinical studies or clinical trials. In this review, we highlight the molecular properties of past and present anti-IgE biologicals and suggest concepts that might improve treatment efficacy of future drug candidates.

The mechanistic and functional profile of the therapeutic anti-IgE antibody ligelizumab differs from omalizumab

Targeting of immunoglobulin E (IgE) represents an interesting approach for the treatment of allergic disorders. A high-affinity monoclonal anti-IgE antibody, ligelizumab, has recently been developed to overcome some of the limitations associated with the clinical use of the therapeutic anti-IgE antibody, omalizumab. Here, we determine the molecular binding profile and functional modes-of-action of ligelizumab. We solve the crystal structure of ligelizumab bound to IgE, and report epitope differences between ligelizumab and omalizumab that contribute to their qualitatively distinct IgE-receptor inhibition profiles. While ligelizumab shows superior inhibition of IgE binding to FcεRI, basophil activation, IgE production by B cells and passive systemic anaphylaxis in an in vivo mouse model, ligelizumab is less potent in inhibiting IgE:CD23 interactions than omalizumab. Our data thus provide a structural and mechanistic foundation for understanding the efficient suppression of FcεRI-dependent allergic reactions by ligelizumab in vitro as well as in vivo.

Allosteric mechanism of action of the therapeutic anti-IgE antibody omalizumab

Immunoglobulin E and its interactions with receptors FcϵRI and CD23 play a central role in allergic disease. Omalizumab, a clinically approved therapeutic antibody, inhibits the interaction between IgE and FcϵRI, preventing mast cell and basophil activation, and blocks IgE binding to CD23 on B cells and antigen-presenting cells. We solved the crystal structure of the complex between an omalizumab-derived Fab and IgE-Fc, with one Fab bound to each Cϵ3 domain. Free IgE-Fc adopts an acutely bent structure, but in the complex it is only partially bent, with large-scale conformational changes in the Cϵ3 domains that inhibit the interaction with FcϵRI. CD23 binding is inhibited sterically due to overlapping binding sites on each Cϵ3 domain. Studies of omalizumab Fab binding in solution demonstrate the allosteric basis for FcϵRI inhibition and, together with the structure, reveal how omalizumab may accelerate dissociation of receptor-bound IgE from FcϵRI, exploiting the intrinsic flexibility and allosteric potential of IgE.

Structural basis of omalizumab therapy and omalizumab-mediated IgE exchange.

Omalizumab is a widely used therapeutic anti-IgE antibody. Here we report the crystal structure of the omalizumab–Fab in complex with an IgE-Fc fragment. This structure reveals the mechanism of omalizumab-mediated inhibition of IgE interactions with both high- and low-affinity IgE receptors, and explains why omalizumab selectively binds free IgE. The structure of the complex also provides mechanistic insight into a class of disruptive IgE inhibitors that accelerate the dissociation of the high-affinity IgE receptor from IgE. We use this structural data to generate a mutant IgE-Fc fragment that is resistant to omalizumab binding. Treatment with this omalizumab-resistant IgE-Fc fragment, in combination with omalizumab, promotes the exchange of cell-bound full-length IgE with omalizumab-resistant IgE-Fc fragments on human basophils. This combination treatment also blocks basophil activation more efficiently than either agent alone, providing a novel approach to probe regulatory mechanisms underlying IgE hypersensitivity with implications for therapeutic interventions.

Critical and direct involvement of the CD23 stalk region in IgE binding

BackgroundThe low-affinity receptor for IgE, FcεRII (CD23), contributes to allergic inflammation through allergen presentation to T cells, regulation of IgE responses, and enhancement of transepithelial allergen migration.ObjectiveWe sought to investigate the interaction between CD23, chimeric monoclonal human IgE, and the corresponding birch pollen allergen Bet v 1 at a molecular level.MethodsWe expressed 4 CD23 variants. One variant comprised the full extracellular portion of CD23, including the stalk and head domain; 1 variant was identical with the first, except for an amino acid exchange in the stalk region abolishing the N-linked glycosylation site; and 2 variants represented the head domain, 1 complete and 1 truncated. The 4 CD23 variants were purified as monomeric and structurally folded proteins, as demonstrated by gel filtration and circular dichroism. By using a human IgE mAb, the corresponding allergen Bet v 1, and a panel of antibodies specific for peptides spanning the CD23 surface, both binding and inhibition assays and negative stain electron microscopy were performed.ResultsA hitherto unknown IgE-binding site was mapped on the stalk region of CD23, and the non–N-glycosylated monomeric version of CD23 was superior in IgE binding compared with glycosylated CD23. Furthermore, we demonstrated that a therapeutic anti-IgE antibody, omalizumab, which inhibits IgE binding to FcεRI, also inhibited IgE binding to CD23.ConclusionOur results provide a new model for the CD23-IgE interaction. We show that the stalk region of CD23 is crucially involved in IgE binding and that the interaction can be blocked by the therapeutic anti-IgE antibody omalizumab.

Development of an antibody that neutralizes soluble IgE and eliminates IgE expressing B cells.

Immunoglobulin E (IgE) plays a key role in allergic asthma and is a clinically validated target for monoclonal antibodies. Therapeutic anti-IgE antibodies block the interaction between IgE and the Fc epsilon (Fcε) receptor, which eliminates or minimizes the allergic phenotype but does not typically curtail the ongoing production of IgE by B cells. We generated high-affinity anti-IgE antibodies (MEDI4212) that have the potential to both neutralize soluble IgE and eliminate IgE-expressing B-cells through antibody-dependent cell-mediated cytotoxicity. MEDI4212 variants were generated that contain mutations in the Fc region of the antibody or alterations in fucosylation in order to enhance the antibody's affinity for FcγRIIIa. All MEDI4212 variants bound to human IgE with affinities comparable to the wild-type (WT) antibody. Each variant was shown to inhibit the interaction between IgE and FcεRI, which translated into potent inhibition of FcγRI-mediated function responses. Importantly, all variants bound similarly to IgE at the surface of membrane IgE expressing cells. However, MEDI4212 variants demonstrated enhanced affinity for FcγRIIIa including the polymorphic variants at position 158. The improvement in FcγRIIIa binding led to increased effector function in cell based assays using both engineered cell lines and class switched human IgE B cells. Through its superior suppression of IgE, we anticipate that effector function enhanced MEDI4212 may be able to neutralize high levels of soluble IgE and provide increased long-term benefit by eliminating the IgE expressing B cells before they differentiate and become IgE secreting plasma cells.

Studies in serum support rapid formation of disulfide bond between unpaired cysteine residues in the VH domain of an immunoglobulin G1 molecule

Recombinant monoclonal antibodies undergo extensive posttranslational modifications. In this article, we characterize major modifications, separated by cation exchange chromatography, on an immunoglobulin G1 (IgG1) monoclonal antibody (mAb). We found that N-terminal cyclization of glutamine residues to pyroglutamate on the light and heavy chains are the major isoforms resolved during cation exchange chromatography. However, using CEX, we also separated and identified isoforms with unpaired cysteine residues in the V(H) domain of the molecule (Cys22-Cys96). Omalizumab, a therapeutic anti-IgE antibody, has unpaired cysteine residues in the V(H) domain between Cys22 and Cys96, and the Fab fragment, containing the unpaired cysteine residues, is reported to have reduced potency. Dynamic interchain disulfide rearrangement, with slow kinetics, was recently reported to take place in serum for an IgG2 molecule and resulted in predictable mature isoforms. Analytical evaluation of our mAb, after recovery from serum, revealed that the unpaired intrachain cysteine residues (Cys22-Cys96) reformed their disulfide bond. The significance of this study is that correct pairing occurred rapidly, and we speculate that thiol molecules such as cysteine, homocysteine, and glutathione in serum provide an environment, outside the endoplasmic reticulum, for correct linkage.

Reduction of serum IgE by depletion of the IgE B cell lineage - a novel approach for the treatment of allergic diseases (140.7)

Abstract Anti-IgE antibody targeting of serum IgE is an efficacious treatment for asthma and other allergic diseases. Currently, therapeutic anti-IgE antibodies neutralize free serum IgE, but do not affect IgE production. We have developed monoclonal antibodies that disrupt IgE production by binding to the M1' domain of human membrane IgE, a 52 amino acid extracellular segment on human IgE-switched B cells and plasmablasts that is not present in serum IgE. Using genetically modified mice that contain the human M1' domain knocked into the mouse IgE locus, we demonstrate that our anti-M1' antibodies reduce serum IgE and IgE plasma cells, but not other immunoglobulin isotypes, in vivo. Anti-M1' antibodies are effective when delivered prophylactically and therapeutically in mouse immunization, asthma, and Nippostrongylus infection models. Moreover, the anti-M1' antibodies are active on primary human cells in vivo, reducing serum IgE and IgE plasma cells in a human PBMC-SCID mouse model. In vitro and in vivo studies indicate that anti-M1' antibodies trigger apoptosis of IgE B cells and may therefore abolish IgE memory. Anti-M1' targeting of IgE B cells is a promising new therapy for the treatment of asthma and allergy.

Targeting immunoglobulin E as a novel treatment for asthma

Omalizumab is a recently developed monoclonal anti-IgE antibody. Clinical trials have demonstrated its efficacy in patients with moderate-to-severe and severe or poorly controlled allergic asthma, in patients with seasonal and perennial allergic disease, and in subjects with concomitant asthma and allergic rhinitis. Patients with more severe asthma appear to obtain the greatest benefit from omalizumab therapy. Omalizumab is well tolerated and has a good safety profile. Anti-inflammatory activity has been shown in both allergic asthma and allergic rhinitis. These results confirm the importance of IgE in allergic disease and support the rationale behind the development of a therapeutic anti-IgE antibody. Omalizumab is a significant addition to current asthma treatments and shows great promise as a therapy for allergic rhinitis, in particular for those patients with concomitant allergic disease.

Anti-IgE monoclonal antibody (omalizumab) in the treatment of atopic asthma and allergic respiratory diseases.

Since the discovery of immunoglobulin E (IgE) antibodies thirty-six years ago, our understanding of the mechanisms of allergy has improved to such an extent that we can now better differentiate allergy from non-allergic hypersensitivity, and allergic/atopic from intrinsic/non-atopic bronchial asthma. IgE antibodies are crucial immune mediators of airway inflammation in allergic atopic asthma and IgE-mediated hypersensitivity reactions are the likely mechanisms of allergen-induced airway obstruction. In addition, IgE may cause chronic airway inflammation in asthma through effector cells activated via high-affinity (Fcepsilon RI) or low-affinity (Fcepsilon RII) IgE receptors. Therapeutic anti-IgE antibodies able to reduce free IgE levels and to block the binding of IgE to Fcepsilon RI without cross-linking IgE and triggering degranulation of IgE-sensitised cells have been developed. This non-anaphylactogenic anti-IgE monoclonal antibody (rhuMAb-E25; omalizumab) binds IgE at the same site as these antibodies bind Fcepsilon RI and Fcepsilon RII. As a consequence, omalizumab inhibits IgE effector functions by blocking IgE binding to high-affinity receptors on IgE effector cells and does not cause mast cell or basophil activation because it cannot bind to IgE on cell surfaces where the Fcepsilon R1 receptor already masks the anti-IgE epitope. Studies in patients with atopic asthma demonstrated that omalizumab decreases serum IgE levels and allergen-induced bronchoconstriction during both the early and late-phase responses to inhaled allergen. In several clinical controlled trials omalizumab resulted to be able to reduce asthma-related symptoms, to decrease corticosteroid use and to improve quality of life of asthmatic patients. The anti-IgE approach to asthma treatment has several advantages, including concomitant treatment of other IgE-mediated diseases (allergic rhinitis, allergic conjunctivitis, atopic dermatitis and food allergies), a favourable side-effect profile and a twice-monthly dosing frequency.

Conditional autoantibodies in urticaria patients: a unifying hypothesis.

Chronic urticaria may be characterized by conditional autoantibodies against the alpha-chain of the high-affinity receptor for IgE (FcepsilonRI). These autoantibodies are termed conditional as they only recognize unoccupied FcepsilonRI. The same conditional reactivity pattern has also been found in sera of atopic and normal healthy donors. Any condition resulting in accessibility of FcepsilonRI will render these autoantibodies anaphylactogenic. This finding offers a unifying hypothesis for the manifestation of different forms of urticaria. Non-immunologic triggers may thereby influence directly or indirectly the number of accessible FcepsilonRI allowing the conditional autoantibodies to induce urticaria symptoms.