Anti-IgE monoclonal antibodies that inhibit allergen-specific histamine release

Biomarkers for Severe Asthma: Lessons From Longitudinal Cohort Studies

Severe asthma (SA) is a heterogeneous disease characterized by uncontrolled symptoms, frequent exacerbations, and lung function decline. The discovery of phenotypes and endotypes of SA significantly improves our understanding of its pathophysiology and allows the advent of biologics blocking multiple molecular targets. The advances have mainly been made in type 2-high asthma associated with elevated type 2 inflammatory biomarkers such as immunoglobulin E (IgE), interleukins (IL)-4, IL-5, and IL-13. Previous clinical trials have demonstrated that type 2 biomarkers, including blood/sputum eosinophils and the fraction of exhaled nitric oxide (FeNO), were correlated to severe airway inflammation, persistent symptoms, frequent exacerbations, and the clinical efficacy of these biomarkers in predicting treatment outcomes of type 2-targeting biologics. However, it is well known that type 2 inflammation is partially attributable to the pathogenesis of SA. Although some recent studies have suggested that type 2-low and mixed phenotypes of asthma are important contributors to the heterogeneity of SA, many questions about these non-type 2 asthma phenotypes remain to be solved. Consequently, many efforts to investigate and find novel biomarkers for SA have also made in their methods. Many cross-sectional experimental studies in large-scale cohorts and randomized clinical trials have proved their value in understanding SA. More recently, real-world cohort studies have been in the limelight for SA research, which is unbiased and expected to give us an answer to the unmet needs of the heterogeneity of SA.

Biologics for Severe Asthma: Treatment-Specific Effects Are Important in Choosing a Specific Agent

Patients with uncontrolled severe persistent asthma have greater morbidity, greater use of health care resources, and more impairment in health-related quality of life when compared with their peers with well-controlled disease. Fortunately, since the introduction of biological therapeutics, patients with severe eosinophilic asthma now have beneficial treatment options that they did not have just a few years ago. In addition to anti-IgE therapy for allergic asthma, 3 new biological therapeutics targeting IL-5 and 1 targeting IL-4 and IL-13 signaling have recently been approved by the Food and Drug Administration for the treatment of severe eosinophilic asthma, and approval of more biological therapeutics is on the horizon. These medications decrease the frequency of asthma exacerbations, improve lung function, reduce corticosteroid usage, and improve health-related quality of life. This article reviews the mechanisms of action, specific indications, benefits, and side effects of each of the approved biological therapies for asthma. Furthermore, this article reviews how a clinician could use specific patient characteristics to decide which biologic treatment may be optimal for a given patient.

Harnessing the immune system via FcγR function in immune therapy: a pathway to next-gen mAbs

The human fragment crystallizable (Fc)γ receptor (R) interacts with antigen‐complexed immunoglobulin (Ig)G ligands to both activate and modulate a powerful network of inflammatory host‐protective effector functions that are key to the normal physiology of immune resistance to pathogens. More than 100 therapeutic monoclonal antibodies (mAbs) are approved or in late stage clinical trials, many of which harness the potent FcγR‐mediated effector systems to varying degrees. This is most evident for antibodies targeting cancer cells inducing antibody‐dependent killing or phagocytosis but is also true to some degree for the mAbs that neutralize or remove small macromolecules such as cytokines or other Igs. The use of mAb therapeutics has also revealed a “scaffolding” role for FcγR which, in different contexts, may either underpin the therapeutic mAb action such as immune agonism or trigger catastrophic adverse effects. The still unmet therapeutic need in many cancers, inflammatory diseases or emerging infections such as severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) requires increased effort on the development of improved and novel mAbs. A more mature appreciation of the immunobiology of individual FcγR function and the complexity of the relationships between FcγRs and antibodies is fueling efforts to develop more potent “next‐gen” therapeutic antibodies. Such development strategies now include focused glycan or protein engineering of the Fc to increase affinity and/or tailor specificity for selective engagement of individual activating FcγRs or the inhibitory FcγRIIb or alternatively, for the ablation of FcγR interaction altogether. This review touches on recent aspects of FcγR and IgG immunobiology and its relationship with the present and future actions of therapeutic mAbs.

The Fab fragment of anti-IgE Cε2 domain prevents allergic reactions through interacting with IgE-FcεRIα complex on rat mast cells

Immunoglobulin E (IgE) plays a central role in the pathogenesis of Type I hypersensitivity through interaction with a high-affinity receptor (FcεRIα). For therapeutic applications, substantial attention has been focused recently on the blockade of the IgE interaction with FcεRIα. While exploring better options for preventing allergic diseases, we found that the Fab fragment of the rat anti-murine IgE antibody (Fab-6HD5) strongly inhibited passive cutaneous anaphylaxis (PCA) in vivo, as well as spleen tyrosine kinase (Syk) activity and β-hexosaminidase release from basophilic leukemia cells in vitro. The in vivo effects of Fab-6HD5 pre-administration were maintained over a long period of time for at least 10 days. Using flow cytometry analysis, we also found that Fab-6HD5 did not recognize the IgE Cε3 domain containing specific binding sites for FcεRIα. Furthermore, deletion-mapping studies revealed that Fab-6HD5 recognized conformational epitopes on the Cε2 domain of IgE. Given that the Cε2 domain plays a key role in stabilizing the interaction of IgE with FcRIα, our results suggest that the specific binding of Fab-6HD5 to the Cε2 domain prevents allergic reactions through destabilizing the preformed IgE-FcεRIα complex on rat mast cells. Although the present study was performed using animal models, these findings support the idea that a certain antibody directed against IgE CH domains may contribute to preventing allergic diseases through interacting with IgE-FcεRIα complex.

Use of biologics to treat acute exacerbations and manage disease in asthma, COPD and IPF

A common feature of chronic respiratory disease is the progressive decline in lung function. The decline can be indolent, or it can be accelerated by acute exacerbations, whereby the patient experiences a pronounced worsening of disease symptoms. Moreover, acute exacerbations may also be a marker of insufficient disease management. The underlying cause of an acute exacerbation can be due to insults such as pathogens or environmental pollutants, or the cause can be unknown. For each acute exacerbation, the patient may require medical intervention such as rescue medication, or in more severe cases, hospitalization and ventilation and have an increased risk of death. Biologics, such as monoclonal antibodies, are being developed for chronic respiratory diseases including asthma, COPD and IPF. This therapeutic approach is particularly well suited for chronic use based on the route and frequency of delivery and importantly, the potential for disease modification. In recent clinical trials, the frequency of acute exacerbation has often been included as an endpoint, to help determine whether the investigational agent is impacting disease. Therefore the significance of acute exacerbations in driving disease, and their potential as a marker of disease activity and progression, has recently received much attention. There is also now a need to standardize the definition of an acute exacerbation in specific disease settings, particularly as this endpoint is increasingly used in clinical trials to also assess therapeutic efficacy. Moreover, specifically targeting exacerbations may offer a new therapeutic approach for several chronic respiratory diseases.

Reduction of total IgE by targeted coengagement of IgE B-cell receptor and FcγRIIb with Fc-engineered antibody

BACKGROUND

Sequestration of IgE to prevent its binding to high-affinity IgE receptor FcεRI on basophils and mast cells is an effective therapy for allergic asthma. IgE production requires differentiation of activated IgE(+) B cells into plasma cells upon allergen sensitization. B-cell receptor signaling is suppressed by the inhibitory IgG Fc receptor FcγRIIb; therefore, we reasoned that a therapeutic antibody that coengages FcγRIIb and IgE B-cell receptor would not only sequester IgE but also suppress its production by blocking IgE(+) B-cell activation and differentiation to IgE-secreting plasma cells.

OBJECTIVE

To explore the effects of IgE sequestration versus IgE suppression by comparing omalizumab to FcγRIIb-optimized anti-IgE antibodies in humanized mouse models of immunoglobulin production.

METHODS

By using a murine anti-IgE antibody as a template, we humanized, increased IgE binding, and modified its Fc domain to increase affinity for FcγRIIb. We next compared effects of this antibody (XmAb7195) versus omalizumab on the secretion of IgE and other isotypes in human PBMC cultures and in PBMC-engrafted severe combined immunodeficiency mice.

RESULTS

Relative to omalizumab, XmAb7195 has a 5-fold higher affinity for human IgE and more than 400-fold higher affinity for FcγRIIb. In addition to sequestering soluble IgE, XmAb7195 inhibited plasma cell differentiation and consequent human IgE production through coengagement of IgE B-cell receptor with FcγRIIb. In PBMC-engrafted mice, XmAb7195 reduced total human IgE (but not IgG or IgM) levels by up to 40-fold relative to omalizumab.

CONCLUSION

XmAb7195 acts by IgE sequestration coupled with an FcγRIIb-mediated inhibitory mechanism to suppress the formation of IgE-secreting plasma cells and reduce both free and total IgE levels.

Potential adverse events with biologic response modifiers

In recent years, an explosion of biologic response modifiers has entered the market to combat a variety of immune-mediated diseases. These can be in the form of recombinant cytokines, as in the case of interferon beta in the treatment of multiple sclerosis, or novel engineered antibodies constructed by combining non-human determinants with a human immunoglobulin scaffold, as in the case of omalizumab in the treatment of allergic asthma. More recently, completely human monoclonal antibodies have also been constructed. Adverse reactions related to these agents can be classified as expected or unexpected events. A number of case studies and a handful of randomized trials have demonstrated the potential toxicities with the use of biologic response modifiers. This article aims to review adverse event profiles of select biologic response modifiers for which the most data is available and are common to a rheumatology, allergy/immunology, and dermatology patient population.

Omalizumab in asthma: approval and postapproval experience

Omalizumab is a humanized mouse monoclonal antibody that binds specifically to the constant region of the immunoglobulin (Ig)E heavy chain. Omalizumab exerts its effects by reducing free serum IgE levels and FcepsilonRI expression on several cell types. These effects have been shown to result in decreased airway inflammation and clinical improvement. In multiple studies, omalizumab has been shown to be efficacious in the treatment of moderate-to-severe persistent asthma and is currently approved by the US Food and Drug Administration for the treatment of moderate-to-severe allergic asthma in patients age 12 yr and older. Moreover, omalizumab has been demonstrated to be effective in the treatment of children and adults with seasonal and perennial allergic rhinitis. Postmarketing surveillance has shown omalizumab to be a relatively safe and well-tolerated medication.

Evaluation of long-term safety of the anti-IgE antibody, omalizumab, in children with allergic asthma

OBJECTIVE

To evaluate the long-term effects of the anti-IgE antibody omalizumab in children with asthma.

METHODS

This was a 28-week, double-blind, randomized, placebo-controlled trial with a 24-week open-label extension. In the core trial 225 children (ages 6 to 12 years) with moderate-to-severe allergic asthma requiring inhaled beclomethasone dipropionate (BDP) received omalizumab every 2 or 4 weeks, and 109 received placebo. BDP dosage was stable for weeks 1 to 16, then reduced during weeks 17 to 24 using strict safety criteria. The lowest dose for optimal asthma control was maintained for 4 more weeks. During the 24-week extension, all patients (n = 309) received open-label omalizumab in addition to other asthma medications. One-year safety data were analyzed.

RESULTS

The incidence of adverse events in patients treated with omalizumab for 52 weeks was similar to those treated for 28 weeks in the core trial, which was generally comparable with placebo. In the 52-week omalizumab group, upper respiratory tract infection and headache were the most frequently reported adverse events (47.1% and 42.7%, respectively). Eleven patients (4.9%) reported urticaria, which resolved spontaneously or with antihistamine, except for 1 patient who was discontinued because of severe urticaria. No anaphylactic reactions or adverse events suggestive of serum sickness or immune complex formation occurred. No anti-omalizumab antibodies were detected in any of the children. There is no evidence that new or more serious adverse events occur with long-term omalizumab treatment.

CONCLUSIONS

Long-term treatment with omalizumab is safe and well tolerated in children with allergic asthma.

Omalizumab improves asthma-related quality of life in patients with severe allergic asthma

BACKGROUND

We have previously shown that omalizumab, a recombinant humanized monoclonal anti-IgE antibody, reduces asthma exacerbations and decreases inhaled corticosteroid (ICS) requirement in patients with severe allergic asthma who were symptomatic despite moderate-to-high doses of ICSs.

OBJECTIVE

The aim of the present study was to assess the effects of omalizumab on asthma-related quality of life (QOL).

METHODS

These analyses were part of a multicenter, 52-week, randomized, double-blind, placebo-controlled study assessing the efficacy, safety, and tolerability of subcutaneous omalizumab (> or =0.016 mg/kg of IgE [in international unit per milliliter] per 4 weeks) in 525 adults with severe allergic asthma. A 16-week steroid-stable phase was followed by a 12-week steroid-reduction phase and a 24-week double-blind extension phase. The effect of treatment on asthma-related QOL was evaluated by using the Asthma Quality of Life Questionnaire (AQLQ) administered at baseline and at weeks 16, 28, and 52.

RESULTS

The 2 treatment groups were comparable in terms of baseline AQLQ scores. At weeks 16, 28, and 52, omalizumab-treated patients demonstrated statistically significant improvements across all AQLQ domains, as well as in overall score. Moreover, a greater proportion of patients receiving omalizumab achieved a clinically meaningful improvement in asthma-related QOL during each phase of the study. Greater than 50% of both patients and investigators rated treatment similarly with omalizumab as excellent or good compared with less than 40% of placebo recipients.

CONCLUSION

In patients requiring moderate-to-high doses of ICSs for severe allergic asthma, the measurably improved disease control afforded by add-on omalizumab therapy is paralleled by clinically meaningful improvements in asthma-related QOL.

Omalizumab improves asthma-related quality of life in children with allergic asthma

BACKGROUND AND OBJECTIVE

Omalizumab is a recombinant, humanized, monoclonal anti-immunoglobulin E (IgE) antibody, developed for the treatment of IgE-mediated diseases. In children with allergic asthma, it was shown to reduce the requirement for inhaled corticosteroids while protecting against disease exacerbation. Here we report the effects of treatment with omalizumab on asthma-related quality of life (AQoL) in children with allergic asthma.

METHODS

This evaluation was part of a previously reported 28-week, randomized, double-blind, placebo-controlled study to assess the efficacy, safety, and tolerability of omalizumab (at least 0.016 mg/kg/IgE [IU/mL] per 4 weeks) in children with allergic asthma who were well controlled on daily treatment with inhaled corticosteroids. Dosage of beclomethasone dipropionate was kept constant for 16 weeks (steroid-stable phase), then reduced over 8 weeks to the minimum effective dose (steroid-reduction phase). This dose was then maintained for the final 4 weeks. The Pediatric Asthma Quality of Life Questionnaire (PAQLQ) was administered at baseline, week 16, and week 28.

RESULTS

Baseline demographics, PAQLQ scores, and other data were comparable for the 2 treatment groups. At the end of the steroid-reduction phase, patients in the omalizumab-treated group reported significant improvements in the "activities" and "symptoms" domain scores as well as overall AQoL compared with placebo. More patients in the omalizumab group achieved clinically relevant (> or =0.5) changes in PAQLQ scores during the course of the study, and this difference was significant for activities and overall AQoL.

CONCLUSION

Omalizumab improves AQoL in children with allergic asthma.

The use of anti-IgE in the treatment of allergic asthma

Allergic sensitization plays a significant role in the development of asthma in many patients. IgE-mediated immune responses play a central role in the pathogenesis of this condition. The development of a treatment that interrupts this pathway is particularly desirable to prevent downstream events. Large-scale trials in patients ranging in age from 6 to 76 years have shown that omalizumab therapy is safe and effective in the treatment of severe allergic asthma. This is particularly true in patients who experience poor disease control despite high doses of inhaled steroids or need oral steroids for control of their disease. These patients are at risk for severe exacerbations despite recommended therapy, and anti-IgE therapy has proved to reduce these episodes. Early aggressive therapy of asthma is needed for maximum control in all age groups. Despite the efficacy of inhaled steroids there is a reluctance to use these agents, especially in younger children. Because of these concerns a long-acting treatment is especially desirable. Because of imperfect effort or technique limiting inhaled medications, introduction of an effective agent that could be administered parenterally at long intervals also is very important. Allergic rhinitis is a co-existing problem in many patients with allergic asthma. Immunotherapy trials have suggested that early intervention with immunotherapy and allergic rhinitis patients may actually prevent the development of asthma. Early treatment of patients with anti-IgE may also have benefits, particularly in those who have concomitant allergic rhinitis in addition to allergic asthma. Although omalizumab has not yet received Food and Drug Administration approval in the United States, it shows great promise in the management of patients requiring high doses of inhaled or oral corticosteroids for control of their disease and to prevent exacerbations of asthma in such patients. Reductions in high doses of inhaled or oral corticosteroids may prevent long-term complications of these treatments.

Omalizumab. A review of the new treatment of allergic asthma and seasonal allergic rhinitis

The causal role of immunoglobulin E (IgE) in triggering the cascade of biochemical events leading to allergic disease is well established. Treatments that selectively inhibit IgE activity are a logical approach in managing the allergic response. Omalizumab is a recombinant humanised monoclonal antibody which specifically binds to the Cε3 domain of immunoglobulin (Ig) E, the site of high-affinity IgE receptor binding. The clinical benefit and steroid-sparing effect of treatment with the anti-immunoglobulin-E (IgE) antibody, Omalizumab, was assessed in patients with moderate-to-severe allergic asthma and seasonal allergic rhinitis. Intravenous and subcutaneous administration of anti-IgE mAb reduces circulating levels of IgE in atopic patients to low levels commonly seen in non-atopic individuals. Anti-IgE therapy offers protection against allergen-induced bronchoconstriction, reduces the need for short acting inhaled beta 2-agonist and corticosteroids among asthmatic patients and reduces severity of symptoms of allergic rhinitis. Adverse events were infrequent in clinical trials of omalizumab, and not significantly different from placebo. The most frequent drug-related event was mild to moderate urticaria. They do not induce anaphylaxis and the occurrence of antibodies against anti-IgE mAb is sporadic. The results of cited studies suggest that humanized anti-IgE monoclonal antibodies may have important immunotherapeutic benefit for treatment of allergic disorders.

The anti-IgE antibody omalizumab reduces exacerbations and steroid requirement in allergic asthmatics

The clinical benefit and steroid-sparing effect of treatment with the anti-immunoglobulin-E (IgE) antibody, omalizumab, was assessed in patients with moderate-to-severe allergic asthma. After a run-in period, 546 allergic asthmatics (aged 12-76 yrs), symptomatic despite inhaled corticosteroids (500-1,200 microg daily of beclomethasone dipropionate), were randomized to receive double-blind either placebo or omalizumab every 2 or 4 weeks (depending on body weight and serum total IgE) subcutaneously for 7 months. A constant beclomethasone dose was maintained during a 16-week stable-steroid phase and progressively reduced to the lowest dose required for asthma control over the following 8 weeks. The latter dose was maintained for the next 4 weeks. Asthma exacerbations represented the primary variable. Compared to the placebo group, the omalizumab group showed 58% fewer exacerbations per patient during the stable-steroid phase (p<0.001). During the steroid-reduction phase, there were 52% fewer exacerbations in the omalizumab group versus the placebo group (p<0.001) despite the greater reduction of the beclomethasone dosage on omalizumab (p<0.001). Treatment with omalizumab was well tolerated. The incidence of adverse events was similar in both groups. These results indicate that omalizumab therapy safely improves asthma control in allergic asthmatics who remain symptomatic despite regular use of inhaled corticosteroids and simultaneous reduction in corticosteroid requirement.

Treatment of allergic asthma with monoclonal anti-IgE antibody. rhuMAb-E25 Study Group

BACKGROUND

Immune responses mediated by IgE are important in the pathogenesis of allergic asthma. A recombinant humanized monoclonal antibody (rhuMAb-E25) forms complexes with free IgE and blocks its interaction with mast cells and basophils. We studied the efficacy of rhuMab-E25 as a treatment for moderate-to-severe allergic asthma.

METHODS

After a 4-week run-in period, we randomly assigned 317 subjects (age range, 11 to 50 years) who required inhaled or oral corticosteroids (or both) to receive either placebo or one of two regimens of rhuMAB-E25: high-dose rhuMAb-E25 (5.8 microg per kilogram of body weight per nanogram of IgE per milliliter or low-dose rhuMAb-E25 (2.5 microg per kilogram per nanogram of IgE per milliliter) intravenously on days 0 (half a dose), 4 (half a dose), and 7 (full dose) and then once every 2 weeks thereafter for 20 weeks. For the first 12 weeks of the study, the subjects continued the regimen of corticosteroids they had received before enrollment. During the following eight weeks, the doses of corticosteroids were tapered in an effort to discontinue this therapy. The primary outcome measure was an improvement in the asthma symptom score at 12 weeks, according to a 7-point scale, in which a score of 1 indicated no symptoms and a score of 7 the most severe symptoms.

RESULTS

A total of 106 subjects were assigned to receive a high dose of rhuMAb-E25, 106 were assigned to receive a low dose, and 105 were assigned to receive placebo. At base line, the mean asthma symptom score was 4.0. After 12 weeks of therapy, the mean (+/-SE) scores were 2.8+/-0.1 in the high-dose group (P=0.008) and 2.8+/-0.1 in the low-dose group (P=0.005), as compared with 3.8+/-0.1 in the placebo group. At 20 weeks, the mean scores were 2.7+/-0.1 in both the high-dose group (P=0.048) and the low-dose group (P=0.14), as compared with 2.9+/-0.1 in the placebo group. More subjects in the two rhuMAb-E25 groups were able to decrease or discontinue their use of corticosteroids than in the placebo group, but only some of the differences were significant. After 20 weeks, serum free IgE concentrations decreased by a mean of more than 95 percent in both rhuMAb-E25 groups. The therapy was well tolerated. After 20 weeks, none of the subjects had antibodies against rhuMAb-E25.

CONCLUSIONS

A recombinant humanized monoclonal antibody directed against IgE has potential as a treatment for subjects with moderate or severe allergic asthma.

Production of a Chimeric Form of CD23 That Is Oligomeric and Blocks IgE Binding to the FcεRI

The low affinity receptor for IgE (FcεRII/CD23) has previously been shown to interact with IgE with a dual affinity. Three chimeric constructs were created containing the lectin domain (amino acids 172–188) or the “neck” and lectin domain (amino acids 157–188) attached to subunits of oligomeric proteins. All chimeras were incapable of interacting with IgE with either a high or low affinity, indicating that the α-helical stalk of CD23 is important for orienting the lectin heads such that an interaction with IgE can occur. This concept received further support in that a chimeric CD23 composed of the human CD23 stalk and the mouse CD23 lectin head bound mouse IgE with a dual affinity, but could only bind rat IgE with a low affinity. Effort was next concentrated on a construct consisting of the entire extracellular (EC) region of CD23. A mutation to the first cleavage site of CD23 (C1M) resulted in a more stable molecule as determined by a decrease of soluble CD23 release. A soluble chimeric EC-C1M was prepared by attaching an isoleucine zipper to the amino terminus (lzEC-C1M). The interaction with IgE by lzEC-C1M was found to be superior to that seen with EC-CD23. The lzEC-C1M could inhibit binding of IgE to both CD23 and the high affinity receptor for IgE, FcεRI, providing further evidence for a strong interaction with IgE. FcεRI inhibition (∼70%) was seen at equimolar concentrations of lzEC-C1M, implying the effectiveness of this chimera and suggesting its potential therapeutic value.