Double-blind placebo-controlled trial of the effect of omalizumab on basophils in chronic urticaria patients

Benralizumab does not elicit therapeutic effect in patients with chronic spontaneous urticaria: results from the phase IIb multinational randomized double-blind placebo-controlled ARROYO trial

BACKGROUND

Chronic spontaneous urticaria (CSU) is a relatively common skin disease associated with hives and angio-oedema. Eosinophils play a role in CSU pathogenesis. Benralizumab, an anti-interleukin-5 receptor-α monoclonal antibody, has been shown to induce nearly complete depletion of eosinophils.

OBJECTIVES

To determine the clinical efficacy and safety of benralizumab in patients with CSU who were symptomatic despite H1 antihistamine treatment.

METHODS

The 24-week, randomized, double-blind, placebo-controlled, phase IIb portion of the ARROYO trial enrolled adult patients with CSU who were currently on H1 antihistamine treatment. Patients were randomized to one of five treatment groups according to benralizumab dose and regimen for a 24-week treatment period. The primary endpoint was change from baseline in Itch Severity Score (ISS)7 at week 12. The key secondary endpoint was change from baseline in Urticaria Activity Score (UAS)7 at week 12. Additional secondary endpoints included other metrics to assess CSU at week 24, blood eosinophil levels, and pharmacokinetics and immunogenicity assessments. Exploratory subgroup analyses were conducted to explore responses according to demographics, clinical features and biomarkers. Safety was assessed in all treatment groups.

RESULTS

Of 155 patients, 59 were randomized to benralizumab 30 mg, 56 to benralizumab 60 mg and 40 to placebo. Baseline and disease characteristics were consistent with what was expected for patients with CSU. There were no significant differences in change from baseline in ISS7 score at week 12 between benralizumab and placebo [benralizumab 30 mg vs. placebo, least-squares mean difference -1.01, 95% confidence interval (CI) -3.28 to 1.26; benralizumab 60 mg vs. placebo, least-squares mean difference -1.79, 95% CI -4.09 to 0.50] nor in change from baseline in UAS7 score at week 12 between benralizumab and placebo (benralizumab 30 mg vs. placebo, P = 0.407; benralizumab 60 mg vs. placebo, P = 0.082). Depletion of blood eosinophil levels was observed at week 24 in patients treated with benralizumab. All other secondary endpoints and exploratory/subgroup analyses indicated no significant differences between benralizumab and placebo. Safety results were consistent with the known profile of benralizumab.

CONCLUSIONS

Although benralizumab resulted in near-complete depletion of blood eosinophils, there was no clinical benefit over placebo.

Research hotspots in urticaria: A bibliometric study of the top 100 most cited articles

BACKGROUND AND PURPOSE

Urticaria is a prevalent recurrent skin allergic condition. Severe itching significantly impacts patients' quality of life. This paper aims to investigate the development status of urticaria through bibliometric analysis to predict future research hotspots and trends.

METHODS

On October 29, 2023, a literature search was conducted in the Web of Science (WOS) database to collect urticaria-related publications. The top 100 most cited articles were charted, and VOSviewer software was utilized for the literature data analysis. A visual analysis was performed on the number of articles, journals, main researchers, keywords, and so on.

RESULTS

The research involved 415 authors from 28 countries, published across 25 journals, ranging from 1963 to 2023. Marcus Maurer was the leading author, with the United States being the foremost country in urticaria research. CEH Grattan received the most citations, and The Medical University of South Carolina had the highest number of publications. Key research focuses include epidemiology, pathogenesis, drug therapy, and quality of life assessments. "Anti-high affinity IgE receptor α chain (FcεRIα)," "chronic idiopathic urticaria," "autoantibodies," "histamine-release" emerged as the keywords with the highest prominence.

CONCLUSION

The field of urticaria research has attracted substantial attention over the past few decades, witnessing rapid development. This study highlighted the top 100 articles by citation frequency within the urticaria field. Bibliometric analysis revealed a shift in treatment methods from traditional antihistamines to biological agents, with significant emphasis on improving the quality of life in chronic urticaria management. These areas represent the current research focal points and indicate future trends in urticaria research.

Comparative efficacy and safety of the treatment by Omalizumab for chronic idiopathic urticaria in the general population: A systematic review and network meta-analysis

BACKGROUND

Omalizumab is the only licensed drug that serves as a third-line treatment for chronic idiopathic urticaria (CIU). The optimum doses of omalizumab remain controversial. Therefore, this study aims to estimate the efficacy and safety of different doses of omalizumab in the treatment of CIU patients.

MATERIALS AND METHODS

Four databases were searched from the database's creation to April 8, 2023. Several keywords such as omalizumab and urticarias were used to retrieve related studies. The meta-analytical outcomes were analyzed in R 4.2.1 software and Stata 15.1 software. Cochrane risk-of-bias tool Ver. 2 was used to evaluate the risk of bias in randomized controlled trials (RCTs).

RESULTS

In total, 2331 patients were included. Five indexes were employed to assess, including weekly Itch Severity Score (ISS7), weekly Hive Severity Score (HSS7), weekly Urticaria Activity Score (UAS7), Dermatology Life Quality Index (DLQI), and adverse events (AE). A 300 mg dose of omalizumab was the optimum dose to treat CIU, followed by the 150 mg dose. Furthermore, 600 mg of omalizumab only showed a significant difference from the placebo in HSS7. No significant statistical difference was observed in AE. Meta-regression analysis revealed that time, as a covariate, was statistically significant in the comparison of omalizumab 150 mg with placebo.

CONCLUSION

300 mg of omalizumab was the optimum dosage to treat CIU patients, with a 150 mg dose also exhibiting good efficacy. Further studies are required to explore the efficacy and safety of different doses of omalizumab in the treatment of CIU patients.

Different doses and courses of omalizumab for patients with chronic spontaneous urticaria: A systematic review with meta-analysis and trial sequential analysis

Background

The stability, efficacy, and safety of omalizumab at different doses and regimens for chronic spontaneous urticaria (CSU) are yet to be studied.

Objective

A systematic review (SR) with meta-analysis (MA) and trial sequential analysis (TSA) was performed to assess the efficacy and safety of omalizumab in CSU.

Methods

Randomised controlled trials (RCTs) of administering omalizumab versus placebo for CSU were searched. Random-effects MAs were performed using planned subgroup analyses. TSA was performed to control for the risk of random errors and assess the stability of our MA results. Publication bias was visually assessed using a contour-enhanced funnel plot and the trim-and-fill method. The quality of RCTs was assessed using the Cochrane Risk of Bias Tool 2.

Results

Twelve studies met the inclusion criteria. Omalizumab had remarkable effects on the patient percentage of the weekly urticaria activity score is zero (UAS = 0) [RR 4.64, 95% CI (3.38, 6.37)], percentage of no angioedema-burdened days [MD 3.15, 95% CI (0.10, 6.19], patient percentage of UAS ≤6 [RR 3.05, 95% CI (2.46, 3.78)], and patient percentage of the weekly itch severity score minimally important difference (ISS7 MID) [RR 1.50, 95% CI (1.36, 1.66)]. Omalizumab was well tolerated across studies [RR 0.98, 95% CI (0.90, 1.08)]. TSA confirmed the above results, except for "the percentage of no angioedema-burdened day".

Conclusion

Among the different doses and courses assessed, omalizumab (300 mg, 12 weeks) can be recommended as an effective treatment for patients with CSU. However, whether omalizumab improves angioedema requires further investigation. The clinical management of angioedema accompanying CSU requires further attention.

Comparative effectiveness and safety of drug therapy for chronic urticaria: a network meta-analysis and risk-benefit assessment

BACKGROUND

Chronic urticaria (CU) is a prevalent chronic skin condition characterized by recurrent wheals. Clinical guidelines recommend multiple drugs for CU treatment. Our study aims to compare the effectiveness and safety of drug therapy for CU.

METHODS

We conducted a comprehensive search of randomized controlled trials (RCTs) and real-world studies (RWSs) in PubMed, EMBASE, and Cochrane. A network meta-analysis (NMA) was conducted to assess the response rate, decline in Urticaria Activity Score over 7 Days (UAS7), Dermatology Life Quality Index (DLQI), and adverse event rates of standard-dose and high-dose H1 antihistamine (H1AH), omalizumab (OMA) 75, 150, and 300 mg, cyclosporine and placebo. The risk-benefit assessment was conducted by probabilistic simulation and stochastic multicriteria acceptability analysis (SMAA).

RESULTS

A total of 39 studies were identified, including 37 RCTs and 2 RWSs. OMA 300 mg and 150 mg both had significantly higher response rate than standard-dose H1AH (p < 0.05, respectively). OMA 300 mg and 150 mg both consistently led to a huge drop in UAS7 and DLQI compared to standard-dose H1AH and high-dose H1AH (p < 0.05).

CONCLUSION

Regarding risk-benefit assessment, OMA 300 mg emerges as the optimal pharmacological intervention for CU, while OMA 150 mg stands as a secondary alternative compared to H1 antihistamines and cyclosporine.

Association Between Serum Total IgE Levels and Clinical Response to Omalizumab for Chronic Spontaneous Urticaria: A Systematic Review and Meta-Analysis

BACKGROUND

Omalizumab is the only biological agent approved for patients with chronic spontaneous urticaria (CSU), but no biomarker is well established for predicting clinical response to omalizumab.

OBJECTIVE

We aimed to determine the association between baseline total serum IgE levels and the effects of omalizumab in patients with CSU.

METHODS

PubMed, Web of Science, Scopus, and Cochrane Library were systematically searched for relevant studies from inception to August 23, 2022. The research protocol was registered on PROSPERO (CRD42022355592). No language restrictions were applied. A random-effects model was used for meta-analysis.

RESULTS

Ten interventional studies, including 1 randomized controlled trial, were included in the final meta-analysis, and a total of 866 patients with CSU were included. A pooled analysis showed significantly higher serum total IgE levels in complete responders (CRs) than in nonresponders (NRs) (mean difference [MD]: 56.509 IU/mL; 95% confidence interval [CI]: 24.230-88.789) and in partial responders (PRs) than in NRs (MD: 62.688 IU/mL; 95% CI: 32.949-92.427), but no significant difference was detected between CRs and PRs. The mean total IgE levels for CRs, PRs, and NRs were 163.154, 179.926, and 51.535 IU/mL, respectively. Further, the serum total IgE levels in early CRs were significantly higher compared with late CRs (MD: 55.194 IU/mL; 95% CI: 13.402-96.986). The sensitivity analyses with the leave-one-out method validated the robustness of all findings.

CONCLUSIONS

This systematic review and meta-analysis provide convincing evidence that pretreatment total serum IgE levels in patients with CSU are associated with clinical responses to omalizumab.

Positive Basophil Tests Are Linked to High Disease Activity and Other Features of Autoimmune Chronic Spontaneous Urticaria: A Systematic Review

BACKGROUND

Chronic spontaneous urticaria (CSU) is believed to be Autoimmune (aiCSU) (type IIb CSU) in at least 8% of patients, associated with mast cell-activating IgG autoantibodies. Basophil tests such as the basophil activation test (BAT) and basophil histamine release assay (BHRA) are considered the best single tests for an aiCSU diagnosis. To date, the strength of associations among a positive BAT and/or BHRA (BAT/BHRA+) and CSU features, patient demographics, and response to treatment remains poorly characterized.

OBJECTIVE

To evaluate the strength of current evidence on basophil tests as parameters for CSU characteristics.

METHODS

We performed a systematic literature search and review to assess the relationship between BAT/BHRA+ and clinical and laboratory parameters of CSU. Of 1,058 records found in the search, 94 studies were reviewed by experts in urticaria and 42 were included in the analysis.

RESULTS

In CSU patients, BAT/BHRA+ showed a strong level of evidence for an association with high disease activity and low levels of total IgE. A weak level of evidence was shown for the association of BAT/BHRA+ and the presence of angioedema, and basopenia.

CONCLUSIONS

Our results suggest that aiCSU defined by BAT/BHRA+ is more active or severe and is linked to other aiCSU markers such as low total IgE/basopenia. Basophil tests should be standardized and implemented in routine clinical care to improve the diagnosis and treatment of patients with aiCSU.

Biomarkers for Monitoring Treatment Response of Omalizumab in Patients with Chronic Urticaria

Chronic urticaria (CU) is a debilitating skin disease affecting around 1% of the population. CU can be subdivided into chronic spontaneous urticaria (CSU) and chronic inducible urticaria (CIndU). Different pathophysiological mechanisms have been proposed to play a role in the development of CU, and these are also being investigated as potential biomarkers in the diagnosis and management of the disease. As of now the only assessment tools available for treatment response are patient reported outcomes (PROs). Although these tools are both validated and widely used, they leave a desire for more objective measurements. A biomarker is a broad subcategory of observations that can be used as an accurate, reproducible, and objective indicator of clinically relevant outcomes. This could be normal biological or pathogenic processes, or a response to an intervention or exposure, e.g., treatment response. Herein we provide an overview of biomarkers for CU, with a focus on prognostic biomarkers for treatment response to omalizumab, thereby potentially aiding physicians in personalizing treatments.

Urticaria and basophils

Chronic spontaneous urticaria (CSU) is a common skin disease without an etiology in the vast majority of cases. The similarity of symptoms and pathology to allergen-induced skin reactions supports that skin mast cell IgE receptor activation is also involved in CSU. Accumulating evidence also supports a role for blood basophils in disease expression. Blood basopenia is noted in active CSU disease with the recruitment of blood basophils to skin lesion sites. Blood basophils further display altered IgE receptor mediated degranulation patterns in two phenotypes that improve in remission. In active CSU subjects, changes in IgE receptor signaling molecule expression levels accompany the altered degranulation function in blood basophils. The success of therapies targeting IgE in CSU patients have also shown that altered blood basophil phenotypes and enumeration have potential use as a disease biomarker.

Chronic spontaneous urticaria: Focus on pathophysiology to unlock treatment advances

Chronic spontaneous urticaria (CSU) is a debilitating skin disease characterized by intensely itchy wheals, angioedema, or both. Symptoms recur spontaneously, on a near-daily basis, over >6 weeks; many patients experience flare-ups over several years and, consequently, reduced quality of life. Differences between the inflammatory profiles of the skin of CSU patients (wheals and nonlesional sites) and healthy controls indicate that key drivers such as mast cells, eosinophils, and basophils interact, release vasoactive mediators, and prime the skin, leaving patients predisposed to symptoms. Many cytokines and chemokines involved in these inflammatory networks and their corresponding intracellular signaling cascades have been identified. These insights informed the development of therapies such as omalizumab, dupilumab, and Bruton's tyrosine kinase (BTK) inhibitors, marking a renewed focus on pathogenesis in CSU clinical research. Despite progress, current therapies provide symptomatic control but do not appear to redress the inflammatory balance in the skin permanently. A deeper understanding of CSU pathogenesis will permit a more targeted approach to developing novel treatments with curative intent. Here, we review what is known about the pathogenesis of CSU and consider how this can be used to identify rational targets to improve patient care further.

Evidence Gaps in Clinical Trials of Pharmacologic Treatment for H1-Antihistamine-Refractory Chronic Spontaneous Urticaria: A Systematic Review and Future Perspectives

No data addressing issues concerning disparities in participant and trial characteristics and trial outcome reporting have been established in clinical trials for H1-antihistamine-refractory chronic spontaneous urticaria (CSU). To better harmonize and compare the different treatment interventions, we systematically evaluated the overall landscape of pharmacological treatments for H1-antihistamine-refractory CSU clinical trials published between 2000 and 2021. This systematic review included 23 randomized clinical trials involving 2480 participants from 22 countries. We found significant increases in the number of globally published and newly tested drugs, especially biologic drugs. Regarding relatively small trials, we found that people living with H1-antihistamine-refractory CSU who were identified as members of minority groups (non-white population), populations of regions other than North America/Europe, and populations of low- to lower/upper-middle-income countries are underrepresented. Most trials were designed to evaluate treatment efficacy and safety profiles; however, less than half of the included trials reported the patient’s perspective in terms of patient-reported outcomes. Disparities in outcome reporting, including clinimetric tools for assessing treatment response and outcome sets, were observed. To close the evidence gap in H1-antihistamine-refractory CSU trials, strategies for improving trial and participant enrollment and standardizing core outcome sets for trial reporting are needed.

The Role of Omalizumab in NSAID-Exacerbated Respiratory Disease: A Narrative Review

Nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (N-ERD) is a condition characterized by the triad of chronic rhinosinusitis with nasal polyps, bronchial asthma, and hypersensitivity to nonsteroidal anti-inflammatory drugs. This article explores the current knowledge on the various pathological mechanism(s) of N-ERD-such as arachidonic acid metabolism, cysteinyl leukotrienes, prostaglandins, platelets, IgE, mast cells, eosinophils, basophils, and innate immune system-and the role of omalizumab in its management. The authors dive deep into the role of IgE in N-ERD and its potential as a therapeutic target. IgE plays a significant role in mediating allergic reactions, is intricately linked with mast cells, interacts with multiple immunopathological pathways involved in N-ERD, and tends to be elevated in patients with N-ERD. Multiple real-world studies, observational studies, and case series, as well as 2 phase III trials, have demonstrated the effectiveness of omalizumab in the management of N-ERD. For a disease with such a well-documented history, the pathophysiology of N-ERD and the most effective ways to manage it remain a mystery. With this background, the authors ask-is IgE a missing piece of the N-ERD puzzle, thus explaining the efficacy of omalizumab in the treatment of the disease?

IgE and high-affinity IgE receptor in chronic inducible urticaria, pathogenic, and management relevance

BACKGROUND

IgE and high-affinity IgE receptor (FcεRI) expression on basophils have been scarcely explored in patients with chronic inducible urticaria (CIndU).

OBJECTIVES

To investigate baseline serum IgE and FcεRI expression on blood basophils in a large cohort of CIndU patients and its relationship to treatment response.

METHODS

Baseline total serum IgE and basophil FcεRI expression measured by flow cytometry in 165 patients with CIndU was studied. The relationship of both parameters with the response to antihistamine and anti-IgE (omalizumab) treatment was considered in a subsample of CIndU patients. FcεRI expression in basophils was assessed by mean fluorescence intensity (MFI) and basophil FcεRI standardized density (receptors/cell).

RESULTS

The median FcεRI expression standardized per density in blood basophils was found significantly higher in patients with CIndU compared to HCs. A positive correlation was found between IgE serum levels and basophil FcεRI expression. Basal FcεRI expression was not related to antihistamine treatment response. However, it was related to omalizumab, and patients responding to omalizumab showed higher basal basophil expression of FcεRI levels. Non-responders to the antihistamine showed significantly higher IgE serum levels.

CONCLUSIONS

FcεRI receptor overexpression in patients with CIndU shows almost the same pattern than chronic spontaneous urticaria. It seems to be independent of CIndU subtypes. Although additional studies would be welcome, our work highlights the relevance of FcεRI receptor regulation in CIndU supporting autoimmune basophil and mast cell activation and may be a biomarker for response to anti-IgE therapy.

EAACI Biologicals Guidelines-Omalizumab for the treatment of chronic spontaneous urticaria in adults and in the paediatric population 12-17 years old

Chronic spontaneous urticaria (CSU) imposes a significant burden on patients, families and healthcare systems. Management is difficult, due to disease heterogeneity and insufficient efficacy of classical drugs such as H₁ R-antihistamines. Better understanding of the mechanisms has enabled a stratified approach to the management of CSU, supporting the use of targeted treatment with omalizumab. However, many practical issues including selection of responders, the definition of response, strategies to enhance the responder rate, the duration of treatment and its regimen (in the clinic or home-based) and its cost-effectiveness still require further clarification. The EAACI Guidelines on the use of omalizumab in CSU follow the GRADE approach in formulating recommendations for each outcome. In addition, future therapeutic approaches and perspectives as well as research priorities are discussed.

Predictors of treatment response in chronic spontaneous urticaria

The current therapeutic algorithm for chronic spontaneous urticaria (CSU), endorsed by the international guideline, entails treatment escalation from second-generation H₁ -antihistamines (sgAHs) to omalizumab and cyclosporine until complete response is achieved. Recently, several predictors of response to these treatment options have been described. Here, we discuss the most promising predictors of response and nonresponse to these treatments in CSU. A systematic search was performed by two independent researchers using the MEDLINE/PubMed database with specific keywords and 73 studies included in the review. Levels of evidence were categorized as strong (robust predictors), weak (emerging predictors) or no association, based on the outcome and number of studies available. High disease activity, high levels of C-reactive protein and D-dimer are robust predictors for a poor or no response to sgAHs. Poor or no response to omalizumab is robustly predicted by low serum levels of total IgE. A good response to cyclosporine is robustly predicted by a positive basophil histamine release assay, whereas low total IgE is an emerging predictor. The response to treatment with sgAHs, omalizumab and cyclosporine can be predicted by the use of markers that are readily available in routine clinical practice. Further studies are needed to confirm these predictors.

Evaluation of Pharmacologic Treatments for H1 Antihistamine-Refractory Chronic Spontaneous Urticaria: A Systematic Review and Network Meta-analysis

Importance

The comparative benefits and harms of all available treatments for H1 antihistamine-refractory chronic spontaneous urticaria (CSU) have not been established.

Objective

To evaluate different treatment effects of pharmacologic treatments among patients with H1 antihistamine-refractory CSU.

Data Sources

Searches were conducted of MEDLINE, Embase, PubMed, Cochrane Library, Web of Science, Scopus, and CINAHL from inception to April 19, 2021, with no language restrictions. Gray literature from Google Scholar, ongoing trial registers, and preprint reports was added to the searches of electronic databases.

Study Selection

Randomized clinical trials using validated measurement tools that investigated the benefits and harms of pharmacologic treatments among adolescent or adult patients with CSU who had an inadequate response to H1 antihistamines were screened for inclusion independently by 2 investigators.

Data Extraction and Synthesis

Two investigators independently extracted study data according to the predefined list of interests. A random-effects model was used to calculate the network estimates reported as standardized mean differences and odds ratios with corresponding 95% CIs.

Main Outcomes and Measures

The primary outcomes that reflect the patient's perspective included changes in urticaria symptoms from baseline and unacceptability of treatment (all-cause dropouts).

Results

Twenty-three randomized clinical trials with 2480 participants that compared 18 different interventions or dosages and placebo were included. The standardized mean differences for change in urticaria symptoms were -1.05 (95% CI, -1.37 to -0.73) for ligelizumab, 72 mg; -1.07 (95% CI, -1.39 to -0.75) for ligelizumab, 240 mg; -0.77 (95% CI, -0.91 to -0.63) for omalizumab, 300 mg; and -0.59 (95% CI, -1.10 to -0.08) for omalizumab, 600 mg. No significant differences in treatment unacceptability were observed. With respect to benefits and harms, the network estimates illustrated that the most efficacious treatments were achieved with ligelizumab, 72 or 240 mg (large beneficial effect) and omalizumab, 300 or 600 mg (moderate beneficial effect).

Conclusions and Relevance

The findings in this meta-analysis suggest that the biologic agents ligelizumab, 72 or 240 mg, and omalizumab, 300 or 600 mg, can be recommended as effective treatments for patients with CSU who have had an inadequate response to H1 antihistamines. Head-to-head trials with high methodologic quality and harmonized design and outcome definitions are needed to help inform subsequent international guidelines for the management of CSU.

Basophil activation test: Mechanisms and considerations for use in clinical trials and clinical practice

The basophil activation test (BAT) is a functional assay that measures the degree of degranulation following stimulation with allergen or controls by flow cytometry. It correlates directly with histamine release. From the dose-response curve resulting from BAT in allergic patients, basophil reactivity (%CD63⁺ basophils) and basophil sensitivity (EC₅₀ or similar) are the main outcomes of the test. BAT takes into account all characteristics of IgE and allergen and thus can be more specific than sensitization tests in the diagnosis of allergic disease. BAT reduces the need for in vivo procedures, such as intradermal tests and allergen challenges, which can cause allergic reactions of unpredictable severity. As it closely reflects the patients' phenotype in most cases, it may be used to support the diagnosis of food, venom and drug allergies and chronic urticaria, to monitor the natural resolution of food allergies and to predict and monitor clinical the response to immunomodulatory treatments, such as allergen-specific immunotherapy and biologicals. Clinical application of BAT requires analytical validation, clinical validation, standardization of procedures and quality assurance to ensure reproducibility and reliability of results. Currently, efforts are ongoing to establish a platform that could be used by laboratories in Europe and in the USA for quality assurance and certification.

Basophils and their effector molecules in allergic disorders

Basophils are the rarest granulocytes which represent <1% of peripheral blood leukocytes. Basophils bear several phenotypic similarities to tissue-resident mast cells and therefore had been erroneously considered as blood-circulating mast cells. However, recent researches have revealed that basophils play nonredundant roles in allergic inflammation, protective immunity against parasitic infections and regulation of innate and acquired immunity. Basophils are recruited to inflamed tissues and activated in an IgE-dependent or IgE-independent manner to release a variety of effector molecules. Such molecules, including IL-4, act on various types of cells and play versatile roles, including the induction and termination of allergic inflammation and the regulation of immune responses. Recent development of novel therapeutic agents has enabled us to gain further insights into basophil biology in human disorders. In this review, we highlight the recent advances in the field of basophil biology with a particular focus on the role of basophils in allergic inflammation. Further studies on basophils and their effector molecules will help us identify novel therapeutic targets for treating allergic disorders.

Biologics for the Use in Chronic Spontaneous Urticaria: When and Which

Guidelines for the treatment of chronic spontaneous urticaria (CSU) recommend the use of the IgE-targeted biologic omalizumab in patients with antihistamine-refractory disease. The rationale for this is supported by the key role of IgE and its high-affinity receptor, FcεRI, in the degranulation of skin mast cells that drives the development of the signs and symptoms of CSU, itchy wheals, and angioedema. Here, we review the current understanding of the pathogenesis of CSU and its autoimmune endotypes. We describe the mechanisms of action of omalizumab, the only biologic currently approved for CSU, its efficacy and ways to improve it, biomarkers for treatment response, and strategies for its discontinuation. We provide information on the effects of the off-label use, in CSU, of biologics licensed for the treatment of other diseases, including dupilumab, benralizumab, mepolizumab, reslizumab, and secukinumab. Finally, we discuss targets for novel biologics and where we stand with their clinical development. These include IgE/ligelizumab, IgE/GI-310, thymic stromal lymphopoietin/tezepelumab, C5a receptor/avdoralimab, sialic acid-binding Ig-like lectin 8/lirentelimab, CD200R/LY3454738, and KIT/CDX-0159. Our aim is to provide updated information and guidance on the use of biologics in the treatment of patients with CSU, now and in the near future.

The Diagnostic Workup in Chronic Spontaneous Urticaria-What to Test and Why

BACKGROUND

In chronic spontaneous urticaria (CSU), the guidelines recommend very limited diagnostic procedures during the routine workup, although additional investigations might be indicated in some patients with CSU. For physicians treating patients with CSU, it is often difficult to decide which diagnostic tests are useful.

OBJECTIVE

To provide recommendations on what diagnostic tests should be performed on which patients with CSU.

METHODS

We performed an extensive literature search on the respective topics and identified relevant questions that should prompt diagnostic procedures based on the published evidence and expert consensus among all authors.

RESULTS

We provide questions, diagnostic testing, where appropriate, and recommendation that should be included when assessing the history of a patient with CSU, to explore and rule out differential diagnoses, to assess patients for underlying causes and modifying conditions, to explore patients for comorbid diseases and consequences of having CSU, and to assess patients for CSU components that can help to predict their disease course and response to treatment.

CONCLUSIONS

Here, we provide physicians treating patients with CSU with information about which clues should lead to which tests and why.

Efficacy and safety of treatment with omalizumab for chronic spontaneous urticaria: A systematic review for the EAACI Biologicals Guidelines

This systematic review evaluates the efficacy and safety of omalizumab for chronic spontaneous urticaria (CSU). PubMed, Embase, and Cochrane Library were searched for RCTs. Critical and important CSU-related outcomes were considered. The risk of bias and the certainty of the evidence were assessed using GRADE. Ten RCTs including 1620 subjects aged 12 to 75 years old treated with omalizumab for 16 to 40 weeks were evaluated. Omalizumab 150 mg does not result in clinically meaningful improvement (high certainty) of the urticaria activity score (UAS)7 (mean difference (MD) -5; 95%CI -7.75 to -2.25), and the itch severity score (ISS)7 (MD -2.15; 95% CI -3.2 to -1.1) does not increase (moderate certainty) quality of life (QoL) (Dermatology Life Quality Index (DLQI); MD -2.01; 95%CI -3.22 to -0.81) and decreases (moderate certainty) rescue medication use (MD -1.68; 95%CI -2.95 to -0.4). Omalizumab 300 mg results in clinically meaningful improvements (moderate certainty) of the UAS7 (MD -11.05; 95%CI -12.87 to -9.24), the ISS7 (MD -4.45; 95%CI -5.39 to -3.51), and QoL (high certainty) (DLQI; MD -4.03; 95% CI -5.56 to -2.5) and decreases (moderate certainty) rescue medication use (MD -2.04; 95%CI -3.19 to -0.88) and drug-related serious AEs (RR 0.77; 95%CI 0.20 to 2.91).

Efficacy and Safety of Biologic Agents in Chronic Urticaria, Asthma and Atopic Dermatitis - A Real-life Experience

Introduction:

Several biologic agents have been approved for the treatment of asthma, chronic urticaria and atopic dermatitis. These therapeutic agents are especially useful for patients with severe or refractory symptoms. We present the real-life experience of four of the commonly used biologic agents in the United Arab Emirates.

Methods:

In this retrospective observational study, we reviewed the demographic, clinical, laboratory and treatment parameters for all patients treated with biologic agents.

Results:

270 patients received biologics at our centre between May 2015 and December 2019 with a median age of 36.5 years. Omalizumab was the most prescribed agent (n=183, 67.8%) followed by dupilumab (n=54, 20%), benralizumab (n=22, 8.1%) and mepolizumab (n=11, 4.1%). Urticaria was the commonest treatment indication (n=148, 55%) followed by asthma (n=105, 39%) and atopic dermatitis (n=13, 5%). All chronic urticaria patients were treated with omalizumab and showed improvement in the mean urticaria control test score from 6.7±4.47 to 12.02±4.17, with a p-value of 0.001. Dupilumab was found to be the most commonly prescribed drug for asthma (37%), followed by omalizumab (32%), benralizumab (21%) and mepolizumab (10%). The mean Asthma control test score for all asthmatics combined increased from 17.06 ± 5.4 to 19.44 ± 5.6, with p-value 0.0012 with treatment; FeNO reduced from 60.02 ± 45.74 to 29.11 ± 27.92, with p-value 0.001 and mean FEV1 improved from 2.38L ± 0.8 to 2.67L ± 0.78, with p-value 0.045. Only 4 patients in the entire cohort reported adverse events.

Conclusion:

Our study demonstrated that biological agents are a safe and effective treatment for atopic asthma, chronic urticaria and atopic dermatitis.

Developments in the field of clinical allergy in 2018 through the eyes of Clinical and Experimental Allergy, Part II

In this article, we describe developments in the field of clinical allergy as described by Clinical and Experimental Allergy in 2018; epidemiology, asthma and rhinitis, clinical allergy and allergens are all covered.

Effects of omalizumab on basophils: Potential biomarkers in asthma and chronic spontaneous urticaria

Omalizumab is an anti-IgE humanized monoclonal antibody approved for the treatment of severe asthma and chronic spontaneous urticaria. Omalizumab binds free serum IgE and antagonizes its interaction with FcεRI, which is considered the main pharmacodynamic mechanism responsible for the clinical response to the treatment. The reduction of IgE serum concentration down-regulates the cellular expression of FcεRI on basophils. However, the biological events occurring on basophils during the therapy with omalizumab are multiple and complex. Here we review the current evidence regarding the specific biological effects of omalizumab on basophils in patients with asthma and chronic spontaneous urticaria. In addition to the modulation of IgE receptors, omalizumab may affect basophils homeostasis, intra-cellular signaling, cellular responsiveness/activation and cytokine release. These effects may be partially responsible for the clinical success of omalizumab and potentially provide useful biological markers for future assessment of the clinical response to the treatment. However, further investigation is required to better elucidate the role of basophils during the treatment with omalizumab.

Improved FcεRI-Mediated CD203c Basophil Responsiveness Reflects Rapid Responses to Omalizumab in Chronic Spontaneous Urticaria

BACKGROUND

Omalizumab is effective in patients with chronic spontaneous urticaria (CSU) although its mechanism of action is poorly understood. Several studies reported that decreased high-affinity IgE receptor (FcεRI)-mediated histamine release and/or responsiveness was characteristic of basophils in patients with CSU. However, few studies have focused on the relationship between changes in basophil responsiveness via FcεRI after omalizumab treatment and the therapeutic effect in patients with CSU.

OBJECTIVE

To assess basophil responsiveness via FcεRI stimulation, as well as FcεRI expression and IgE binding on blood basophils from patients with CSU before and after omalizumab treatment and its possible association with the clinical response.

METHODS

We analyzed 34 patients with CSU treated with omalizumab who were categorized as fast responders (FRs) (n = 20) and non or slow responders (N/SRs) (n = 14). CD203c expression induced by FcεRI stimulation, and IgE and FcεRI expressions on blood basophils from patients with CSU before and after omalizumab treatment were analyzed. Basophil responsiveness via FcεRI stimulation was observed in vitro using basophils pretreated with omalizumab.

RESULTS

FRs had increased CD203c responsiveness after treatment with omalizumab compared with N/SRs. This improvement of basophil responsiveness via FcεRI stimulation in FRs was not observed in peripheral blood basophils preincubated with omalizumab in vitro, suggesting that omalizumab does not directly affect circulating pre-existing abnormal basophils.

CONCLUSION

Increased basophil responsiveness via FcεRI after omalizumab treatment is associated with the therapeutic effect and mechanism of action of omalizumab.

Basophil Activation as Marker of Clinically Relevant Allergy and Therapy Outcome

For some years now the basophil activation test (BAT) using flow cytometry has emerged as a powerful tool and sensitive marker that can be used to detect clinically relevant allergies, provide information on the severity of an allergic reaction, and monitor therapies. Compared to other in vitro diagnostic tests, BAT seems to have a better informative value in terms of clinical relevance. In general, the BAT can be used for the diagnosis of the most common forms of IgE-mediated allergy such as hymenoptera venom allergy, inhalant allergy, food allergy, and drug allergy. Various basophil markers and parameters have been established which, depending on the trigger of the respective allergy, can provide information on the clinical relevance of sensitization, on the development of natural tolerance, on trigger thresholds, and on the severity of the allergic reaction. The BAT also serves as a suitable follow-up instrument for various therapeutic approaches such as specific immunotherapy, desensitization protocols, or use of anti-IgE-antibodies for the various diseases. Quality controls for routine use, standardization, and automatization are expected to expand the range of applications for the above-mentioned indications.

The Absolute Basophil Count

The absolute basophil count (cells/L) can be determined by manual counting of peripheral blood smears or using cell counting chambers as well as by automated hematology analyzers and fluorescence flow cytometry. Manual basophil counting of peripheral blood smears is currently regarded as the reference method, although the limitations of this method (distribution, observer, and statistical errors) are widely recognized. Automated hematology analyzers offer an advantage of larger numbers of counted cells and high throughput but are characterized by inconsistent analytical performance for basophil enumeration. Flow cytometric enumeration of circulating basophils using panels of monoclonal antibodies is being developed as novel candidate reference method for the absolute basophil count in peripheral blood. Basophil counting using fluorescence flow cytometry is characterized by high precision and statistical superiority. Emerging innovative technologies for absolute cell counts include imaging flow cytometry, mass cytometry, and on-chip blood counting, but their analytical performance for absolute basophil counts is yet to be established. Here, we describe various techniques for absolute basophil counting in peripheral blood including manual basophil counts in smears and hemocytometers and flow cytometric methodologies using double-platform, bead-based, and volumetric approaches.

Presence of positive skin prick tests to inhalant allergens and markers of T2 inflammation in subjects with chronic spontaneous urticaria (CSU): a systematic literature review

BACKGROUND

Current guidelines do not recommend performing aeroallergen skin prick testing (SPT) in chronic spontaneous urticaria (CSU).

OBJECTIVE

The objective of this review was to investigate the presence of aeroallergen sensitization and markers of T2 inflammation in subjects with CSU.

METHODS

Systematic literature reviews to identify all studies that evaluated the presence of T2 markers of allergic inflammation in CSU subjects were performed.

RESULTS

In 16 studies that assessed the prevalence of positive SPT to multiple aeroallergens in CSU, 38.5% of CSU subjects had positive SPT. In three controlled studies, 34.2% of CSU subjects had positive SPT to multiple aeroallergens, compared to 13.6% of controls (p = 0.047). In 18 studies that assessed the prevalence of house dust mite (HDM) positive SPT in CSU, 27.5% of CSU subjects had positive SPT. In three controlled studies, 27.5% of CSU subjects had positive SPT to HDM, compared to 2.1% of controls (p = 0.047). Overall, CSU subjects were 3.1 times more likely to be aeroallergen-sensitized (95% CI 1.7-5.8, p = 0.0002) and 6.1 times more likely to be HDM-sensitized (95% CI 3.7-9.9, p < 0.00001) than controls. Mean total serum IgE (tIgE) levels were 238 kU/L and median tIgE levels were 164 kU/L, which was greater than the upper 90th percentile of normal (< 137 kU/L). Compared to healthy controls, CSU subjects were 6.5 times more likely to have IgG autoantibody against FcεR1α (p = 0.001), 2.4 times more likely to have IgG anti-IgE antibody (p = 0.03) and 5 times more likely to have anti-thyroid peroxidase (anti-TPO) antibody (p = 0.02). When corticosteroids were withheld for ≥ 28 days, mean blood eosinophil percentage was elevated at 5.9% (normal < 4%), but other studies reporting absolute count found the mean was in the normal range, 239 × 10 6 / L (normal < 400 × 10 6 / L).

CONCLUSION

Increased aeroallergen sensitization, tIgE, autoantibodies and blood eosinophil percentage in the CSU subjects indicates the possible importance of T2 inflammation in the pathogenesis of CSU. Further studies may be warranted to determine if specific allergen avoidance, desensitization or improvement in the mucosal allergic inflammation present in asthma and/or rhinitis has any benefit in the management of CSU.

Omalizumab does not lead to a distinct alteration in hematological parameters and complete blood count-derived inflammation biomarkers except for basophil count

PURPOSE

Omalizumab is a monoclonal anti-IgE antibody used to treat patients with chronic spontaneous urticaria by decreasing free IgE levels. Omalizumab may have an anti-inflammatory effect by inhibiting T-cell activation and inducing eosinophil apoptosis. In this study, we evaluated the effect of omalizumab on hematological parameters and inflammation biomarkers in patients with chronic spontaneous urticaria.

METHODS

Between July 2018 and November 2019, medical records of 60 patients (44 female, 16 male) with chronic spontaneous urticaria who were treated with omalizumab were reviewed retrospectively. Hematological parameters and inflammation biomarkers including the neutrophil/lymphocyte, monocyte/lymphocyte, platelet/lymphocyte and mean platelet volume/platelet count ratios were compared before and after 12 weeks of omalizumab treatment.

RESULTS

The absolute count of basophils and percentage of basophils increased significantly after omalizumab treatment (p = 0.04, p = 0.004). The absolute count of eosinophils, percentage of eosinophils, neutrophil/lymphocyte, monocyte/lymphocyte, and mean platelet volume/platelet ratios decreased, while platelet/lymphocyte ratio increased after omalizumab treatment. Nevertheless, these changes were not statistically significant.

CONCLUSIONS

Increased basophil counts suggest that omalizumab has a crucial effect through basophils in chronic spontaneous urticaria. Further studies focussing on basophils may contribute to the literature both to elucidate the etiopathogenesis of urticaria and to improve novel treatment agents for the disease. On the other hand, our study revealed that omalizumab did not have a distinct effect on complete blood count-derived inflammation biomarkers and thus inflammation.

Response of FcεRI-bearing leucocytes to omalizumab in chronic spontaneous urticaria

BACKGROUND

The pathogenesis of chronic spontaneous urticaria (CSU) and the mechanism of action of omalizumab in CSU remain unclear.

OBJECTIVE

In this study, we assessed the responsiveness and FcεRI expression of various subsets of leucocytes in patients with CSU treated with omalizumab.

METHODS

In this prospective cohort study, 30 patients were treated with 6 administrations of 300 mg omalizumab every 4 weeks, followed by a follow-up period of 12 weeks. FcεRI expression and the percentage of basophils, monocytes, and dendritic cell subsets were analysed before and during treatment, and after follow-up. In addition, anti-IgE- and C5a-induced basophil degranulation was measured. The results were correlated with disease activity and response to omalizumab.

RESULTS

In addition to a rapid and significant reduction in FcεRI on basophils, we demonstrated a reduction in FcεRI on plasmacytoid dendritic cells during omalizumab treatment, which persisted until 3 months after discontinuation. FcεRI expression on basophils and its reduction did not correlate with the treatment response. Omalizumab led to an increased percentage of basophils in blood but not of the other FcεRI-bearing leucocytes. Basophil responsiveness was differentially affected; anti-IgE-, but not C5a-induced basophil degranulation increased during the treatment. Apart from clinical non-responders showing a stronger increase in anti-IgE-induced basophil degranulation over a period time, no differences were found in omalizumab responders vs non-responders.

CONCLUSIONS/CLINICAL RELEVANCE

FcεRI expression on basophils decreased rapidly, while anti-IgE-induced degranulation significantly increased due to omalizumab treatment in patients with CSU, persisting at least for 3 months after stopping the treatment. None of the markers were able to predict the effectiveness of treatment. Whether basophils play a role in omalizumab responsiveness in CSU remains unclear.

Effectiveness and safety of Omalizumab in the treatment of chronic spontaneous urticaria: Systematic review and meta-analysis

INTRODUCTION

Chronic spontaneous urticaria (CSU) affects approximately 1% of the population, affecting both children and adults. Omalizumab (Oma) is a therapeutic option for patients with refractory forms of CSU.

OBJECTIVES

To determine the effectiveness and safety of Oma in the treatment of CSU.

METHODS

Systematic review (Cochrane Collaboration methodology) of randomized clinical trials comparing Oma to placebo in refractory CSU treatment. The search is based on MEDLINE; EMBASE, Central Cochrane Library, and LILACS. The outcomes evaluated were: control of the illness, adverse events, and quality of life.

RESULTS

Of the 848 identified studies 13 were selected for further review and six were included in the meta-analysis. For all outcomes, high-quality evidence has confirmed that Oma is effective in the treatment of CSU. The dosage of 300mg/month achieved better results; namely a significant reduction in pruritus, papules, and urticaria activity, as well as an increase in the number of patients with a controlled condition, improvement in the quality of life and no differences in adverse events compared to the placebo.

CONCLUSIONS

High-quality evidence demonstrates that Oma is effective and safe in the treatment of CSU refractory to therapy with H1 antihistamines.

Effects of Omalizumab on FcεRI and IgE Expression in Lesional Skin of Bullous Pemphigoid

Recent studies suggest an important role of immunoglobulin E (IgE) as an alternative pathogenic pathway in the development of bullous pemphigoid (BP), as the most frequent subepidermal blistering disease of the skin Use of IgE targeted therapies, such as omalizumab, has been shown promising in recent studies. The aim of this study was to assess the effect of omalizumab on FcεRI and IgE expression on circulating basophils and on lesional intradermal cells in BP to generate insight into the immunological effects of omalizumab in BP. We report two cases of BP patients treated with omalizumab. Efficacy of treatment was assessed clinically 4 months after initiation of the therapy. Lesional and non-lesional skin biopsies where taken before and 4 weeks after initiation of omalizumab therapy. In addition, FcεRI expression on circulating cells and IgE levels in serum and in the skin samples, as well as anti-BP180 and anti-BP230 in serum and eosinophils and basophils counts in blood were assessed before and during treatment. Both patients showed a marked improvement after 4 months, with no adverse effects. Down-regulation of FcεRI, IgE in lesional skin and on circulating basophils were observed in parallel with clinical improvement. The current case study supports the role of omalizumab in the treatment of a subset of BP patients. Our observations suggest that omalizumab represents a valuable therapeutic option in the management of BP patients. Its efficacy might be related to reduction in FcεRI+ and IgE+ basophils and intradermal cells.

Relevance of the Basophil High-Affinity IgE Receptor in Chronic Urticaria: Clinical Experience from a Tertiary Care Institution

BACKGROUND

The high-affinity IgE receptor (FcεRI) expression on effector cells has been poorly characterized in patients with chronic urticaria (CU) to date.

OBJECTIVES

To investigate the FcεRI expression on blood basophils in a large cohort of patients with CU and its potential relationship with relevant features of the disease.

METHODS

Basophil FcεRI expression was measured by flow cytometry in 287 patients with CU (192 with chronic spontaneous urticaria and 95 with chronic inducible urticaria) at their initial evaluation in our department. A control group of healthy nonatopic individuals was included to provide reference data, and the effect of antihistamine and anti-IgE therapy on the basophil FcεRI expression was also evaluated in a cohort of patients with CU.

RESULTS

The median FcεRI expression was found significantly higher in patients with CU compared with healthy controls (P < .0001). A positive correlation was found between serum IgE levels and basophil FcεRI expression (R = 0.422; P < .001). Significantly higher FcεRI levels on basophils were detected in patients with CU who presented with concomitant atopic features (P = .003), negative autologous serum skin test (P = .002), negative autologous plasma skin test (P = .009), or undetected levels of antithyroid antibodies (P = 0.01). Baseline FcεRI expression was not related to the activity and duration of the disease, and was not significantly modified during antihistamine therapy; however, it correlated with the clinical response to omalizumab (P = .003).

CONCLUSIONS

Although further multicenter studies are needed to corroborate these findings, the assessment of basophil FcεRI levels might be relevant in daily clinical practice supporting an autoimmune pathogenesis and predicting response to anti-IgE treatment.

Update on Omalizumab for Urticaria: What's New in the Literature from Mechanisms to Clinic

PURPOSE OF REVIEW

Since omalizumab has been approved for urticaria, numerous randomized and real-life observational trials have been published. We reviewed the period January 2017-February 2018.

RECENT FINDINGS

Omalizumab is effective for the control of urticaria recalcitrant to antihistamines in different populations globally. The ratio of total serum IgE 4-week/baseline ≥2 can predict response with a high likelihood. In observational real-life trials, doses have been adjusted on an individual basis: in some populations, up to two-thirds of the patients can be controlled with 150 mg/month; however, others are still not controlled with 300 mg/month. In these, 150 mg bimonthly could be tried, before up-dosing to 450 mg/month. On the long run (up to 3 years) omalizumab kept its efficacy. In many patients, dosing intervals could be augmented (6-8 weeks, some even more). After a 12-month treatment, about 20% showed long-term remission without relapse. Some biomarkers are being detected. Adjusting omalizumab doses in urticaria patients could enhance efficacy (shortening dosing interval and/or augmenting dose) and save costs (after 12 months: extending dosing interval and/or reducing dose).