Anti-IgE in allergic asthma and rhinitis: an update

Moving toward consensus on diagnosis and management of severe asthma in adults

Asthma is a considerable health problem with an increasing global prevalence. The burden of severe asthma is expected to notably increase in the following years. Some misleading concepts that sometimes appear in the literature can drive the physician responsible for a patient's management to make incorrect decisions. Furthermore, some of the concepts that appear in the literature and in the guidelines may not be clear to understand, follow or adapt to regional and local realities. This could again drive the physicians responsible for a patient's management to make incorrect clinical judgments. In this article, we review the definition, prevalence and immunopathology of severe asthma, describe the asthma phenotypes, clinical features and comorbidities, the diagnosis of severe asthma and personalized asthma treatment. At the end, we offer a treatment approach based on literature publications, personalized medicine and marketed biologic treatment options.

Variability of total and free IgE levels and IgE receptor expression in allergic subjects in and out of pollen season

The inter- and intra-individual variability and seasonal variation of IgE, and high (FcεRI)- and low-affinity (CD23) IgE receptor expression in blood of seasonal allergic rhinitis (SAR) subjects, is not well studied. Thirty-two otherwise healthy subjects with a history of SAR to birch pollen and a positive skin prick test to birch pollen were sampled three times out of the pollen season and three times during the pollen season. FcεRI and CD23 expressions were analysed using flow cytometry. Total IgE was analysed using ImmunoCAP(®) and free IgE was analysed with a novel customised research assay using an IgG-FcεRI-chimera protein coupled to ImmunoCAP as capture reagent, ImmunoCAP-specific IgE conjugate and ImmunoCAP IgE calibrators. The performance of the free IgE assay was compared well with the reference ImmunoCAP total IgE assay. The working range of the assay was 0.35-200 kU/l IgE. FcεRI expression on basophils and CD23 expression on B cells showed low intrasubject variability both in and out of the pollen season (<10% CV). There was a small seasonal difference with lower total IgE levels (120 versus 128 kU/l; P = 0.004) and FcεRI expression (283 versus 325 mean fluorescence intensity (MFI); P < 0.001) during the pollen season. IgE, FcεRI expression and CD23 expression fulfilled biomarker and assay requirements of variability, and allergen exposure affected the biomarkers only to a minor degree. The free IgE assay may be used for measurement of free IgE levels in patients after anti-IgE antibody treatment.

Anti-IgE--emerging opportunities for Omalizumab

INTRODUCTION

Omalizumab is a recombinant DNA-derived humanized IgG1 monoclonal antibody that selectively binds to free and membrane-bound immunoglobulin E (IgE) antibodies. Omalizumab has been licensed for use in severe allergic asthma. A search on the website clinicaltrials.gov reveals there are currently 109 clinical trials with Omalizumab of which 46 are for conditions other than asthma.

AREAS COVERED

In addition to asthma, Omalizumab has been investigated in various other conditions including perennial and seasonal allergic rhinitis (AR), peanut allergy, latex allergy, atopic dermatitis, chronic urticaria (CU), idiopathic anaphylaxis, mastocytosis, eosinophilic gastroenteritis and nasal polyposis. This review aims to look at the various randomised and non-randomised clinical trials, case series and case reports for the role of Omalizumab in conditions other than asthma. Numerous clinical trials have shown a positive light on the role of Omalizumab in conditions other than asthma.

EXPERT OPINION

We feel that the future of Omalizumab would include a more diverse range of clinical conditions, and future trials should not only look into the clinical usefulness but also the economic impact of using this interesting molecule.

Off-label use of omalizumab in non-asthma conditions: new opportunities

Allergic diseases are mediated by IgE and, hence, neutralizing IgE to attenuate type I hypersensitivity reactions may result in clinical benefits. This has been mainly established in several large pre- and postmarketing studies of the humanized monoclonal anti-IgE antibody, omalizumab, in patients with allergic asthma. In this patient population, omalizumab has been shown to have beneficial effects in subjective and objective outcome measures, as well as resulting in reductions in medication use. Omalizumab is now globally licensed for use in severe persistent asthma. However, a growing number of reports suggest that anti-IgE treatment may also be beneficial to patients suffering from other IgE-related conditions, including allergic rhinitis, peanut allergy, latex sensitivity, atopic dermatitis, chronic urticaria and allergic bronchopulmonary aspergillosis. For these patients, and specifically for those with severe refractory disease, anti-IgE treatments might have the potential of reducing their financial burden both in terms of medical costs and of loss of productivity in missed work and school days. In this reveiw, we evaluate the evidence in support of a more extensive role for omalizumab in a number of non-asthma IgE-related conditions, and particularly where intensive treatment has not been effective. However, studies with larger numbers of well-characterized patients will be necessary to provide sound evidence regarding the benefit of IgE blockade in these challenging conditions.

Persistent elevation of peripheral blood myeloid cell counts associated with omalizumab therapy

PURPOSE

A case of persistent hematologic abnormalities in a patient receiving long-term omalizumab therapy for severe asthma is reported.

SUMMARY

During the course of her treatment at an asthma clinic, a 24-year-old woman was noted to have increased white blood cell counts, with elevated myeloid cell counts; the blood abnormalities were first documented more than 12 months previously. The woman had been taking omalizumab for more than 2 years and was also receiving immune globulin therapy for common variable immunodeficiency. Based on the results of bone marrow aspiration and biopsy, she was diagnosed as having mild neutrophilia, possibly related to past corticosteroid therapy, but there was no evidence of a malignancy, a hemophagocytic syndrome, or an infectious, myeloproliferative, or lymphoproliferative process. Pursuant to a multidisciplinary medication review, the use of omalizumab was identified as a potential factor in the myeloid cell elevations and discontinued. About 1 month after omalizumab therapy was halted, the patient's myeloid cell counts normalized. The temporal association of omalizumab use and blood abnormalities in this case, coupled with the lack of data on the drug's long-term hematologic effects, suggests a need for cautious use and close monitoring of omalizumab therapy, particularly in younger patients.

CONCLUSION

A patient with asthma and common variable immunodeficiency developed an elevation of peripheral blood myeloid cells that was first noticed 29 months after the initiation of monthly omalizumab injections. Omalizumab was discontinued, and the abnormality persisted for 1 month after the last dose. The patient's blood count results remained within normal limits 3 months after the last dose.

Unusual asthma syndromes and their management

Asthma usually presents with symptoms of wheeze, dyspnoea and cough. However, clinicians should be aware of atypical presentation of this disorder when cough is the main or only symptom in conditions such as cough-variant asthma, nonasthmatic eosinophilic bronchitis and atopic cough. Early diagnosis and treatment of these conditions with inhaled corticosteroids improves symptoms in the majority of patients. Up to 10% of patients with asthma remain poorly controlled in spite of optimal standard therapy. These patients have been encompassed under the term 'treatment-refractory asthma' (TRA), have the greatest morbidity and are responsible for more than 50% of healthcare costs. In this review we discuss investigations, management and pathophysiology of the various phenotypes of atypical presentations of asthma as well as novel biological agents licensed and those that have been reported in clinical trials in terms of their efficacy and safety in TRA.

Severe asthma and the omalizumab option

Atopic diseases and asthma are increasing at a remarkable rate on a global scale. It is now well recognized that asthma is a chronic inflammatory disease of the airways. The inflammatory process in many patients is driven by an immunoglobulin E (IgE)-dependent process. Mast cell activation and release of mediators, in response to allergen and IgE, results in a cascade response, culminating in B lymphocyte, T lymphocyte, eosinophil, fibroblast, smooth muscle cell and endothelial activation. This complex cellular interaction, release of cytokines, chemokines and growth factors and inflammatory remodeling of the airways leads to chronic asthma. A subset of patients develops severe airway disease which can be extremely morbid and even fatal. While many treatments are available for asthma, it is still a chronic and incurable disease, characterized by exacerbation, hospitalizations and associated adverse effects of medications. Omalizumab is a new option for chronic asthma that acts by binding to and inhibiting the effects of IgE, thereby interfering with one aspect of the asthma cascade reviewed earlier. This is a humanized monoclonal antibody against IgE that has been shown to have many beneficial effects in asthma. Use of omalizumab may be influenced by the cost of the medication and some reported adverse effects including the rare possibility of anaphylaxis. When used in selected cases and carefully, omalizumab provides a very important tool in disease management. It has been shown to have additional effects in urticaria, angioedema, latex allergy and food allergy, but the data is limited and the indications far from clear. In addition to decreasing exacerbations, it has a steroid sparing role and hence may decrease adverse effects in some patients on high-dose glucocorticoids. Studies have shown improvement in quality of life measures in asthma following the administration of omalizumab, but the effects on pulmonary function are surprisingly small, suggesting a disconnect between pulmonary function, exacerbations and quality of life. Anaphylaxis may occur rarely with this agent and appropriate precautions have been recommended by the Food and Drug Administration (FDA). As currently practiced and as suggested by the new asthma guidelines, this biological agent is indicated in moderate or severe persistent allergic asthma (steps 5 and 6).