Similarities and differences in peripheral itch and pain pathways in atopic dermatitis.

Atopic dermatitis (AD) is predominantly characterized by intense itching, but concomitant skin pain is experienced by more than 40% of patients. Patients with AD display considerable somatosensory aberrations, including increased nerve sensitivity to itch stimuli (hyperknesis), perception of itch from innocuous stimuli (alloknesis), or perception of pain from innocuous stimuli (allodynia). This review summarizes the current understanding of the similarities and differences in the peripheral mechanisms underlying itch and pain in AD. These distinct yet reciprocal sensations share many similarities in the peripheral nervous system, including common mediators (such as serotonin, endothelin-1, IL-33, and thymic stromal lymphopoietin), receptors (such as members of the G protein-coupled receptor family and Toll-like receptors), and ion channels for signal transduction (such as certain members of the transient receptor potential [TRP] cation channels). Itch-responding neurons are also sensitive to pain stimuli. However, there are distinct differences between itch and pain signaling. For example, specific immune responses are associated with pain (type 1 and/or type 3 cytokines and certain chemokine C-C [CCL2, CCL5] and C-X-C [CXCL] motif ligands) and itch (type 2 cytokines, including IL-31, and periostin). The TRP melastatin channels TRPM2 and TRPM3 have a role in pain but no known role in itch. Activation of µ-opioid receptors is known to alleviate pain but exacerbate itch. Understanding the connection between itch and pain mechanisms may offer new insights into the treatment of chronic pain and itch in AD.

Inhibition of Mast Cell Degranulation by Novel Small Molecule MRGPRX2 Antagonists.

BACKGROUND: Mas-related G-protein coupled receptor X2 (MRGPRX2) is a promiscuous receptor on mast cells that mediates IgE-independent degranulation and has been implicated in multiple mast cell-mediated disorders, including chronic urticaria, atopic dermatitis, and pain disorders. Although it is a promising therapeutic target, few potent, selective, small molecule antagonists have been identified, and functional effects of human MRGPRX2 inhibition have not been evaluated in vivo. OBJECTIVE: We identified and characterized novel, potent, and selective orally active small molecule MRGPRX2 antagonists for potential treatment of mast cell-mediated disease. METHODS: Antagonists were identified using multiple functional assays in cell lines overexpressing human MRGPRX2, LAD2 mast cells, human peripheral stem cell-derived mast cells, and isolated skin mast cells. Skin mast cell degranulation was evaluated in Mrgprb2em(-/-) knockout (KO) and Mrgprb2em(MRGPRX2) transgenic human MRGPRX2 knock-in (KI) mice by assessment of agonist-induced skin vascular permeability. Ex vivo skin mast cell degranulation and associated histamine release was evaluated by microdialysis of human skin tissue samples. RESULTS: MRGPRX2 antagonists potently inhibited agonist-induced MRGPRX2 activation and mast cell degranulation in all mast cell types tested, in an IgE-independent manner. Orally administered MRGPRX2 antagonists also inhibited agonist-induced degranulation and resulting vascular permeability in MRGPRX2 KI mice. In addition, antagonist treatment dose dependently inhibited agonist-induced degranulation in ex vivo human skin. CONCLUSION: MRGPRX2 small molecule antagonists potently inhibited agonist-induced mast cell degranulation in vitro and in vivo as well as ex vivo in human skin, supporting potential therapeutic utility as a novel treatment for multiple human diseases involving clinically relevant mast cell activation.

Mast cell silencing: A novel therapeutic approach for urticaria and other mast cell-mediated diseases.

Chronic urticaria (CU) is a mast cell (MC)-dependent disease with limited therapeutic options. Current management strategies are directed at inhibiting IgE-mediated activation of MCs and antagonizing effects of released mediators. Due to the complexity and heterogeneity of CU and other MC diseases and mechanisms of MC activation-including multiple activating receptors and ligands, diverse signaling pathways, and a menagerie of mediators-strategies of MC depletion or MC silencing (i.e., inhibition of MC activation via binding of inhibitory receptors) have been developed to overcome limitations of singularly targeted agents. MC silencers, such as agonist monoclonal antibodies that engage inhibitory receptors (e.g., sialic acid-binding immunoglobulin-like lectin8 -[Siglec-8] [lirentelimab/AK002], Siglec-6 [AK006], and CD200R [LY3454738]), have reached preclinical and clinical stages of development. In this review, we (1) describe the role of MCs in the pathogenesis of CU, highlighting similarities with other MC diseases in disease mechanisms and response to treatment; (2) explore current therapeutic strategies, categorized by nonspecific immunosuppression, targeted inhibition of MC activation or mediators, and targeted modulation of MC activity; and (3) introduce the concept of MC silencing as an emerging strategy that could selectively block activation of MCs without eliciting or exacerbating on- or off-target, immunosuppressive adverse effects.

Efficacy and safety of on-demand versus daily rupatadine in chronic spontaneous urticaria: A randomized trial.

BACKGROUND: Non-sedating H1 -antihistamines (nsAH) are the most commonly used treatment for chronic spontaneous urticaria (CSU). Many patients use them as on-demand (OD) therapy rather than a maintenance treatment. Here, we compared OD versus daily maintenance treatment with the nsAH rupatadine, assessed the efficacy of rupatadine updosing, and investigated potential long-term disease-modifying effects. METHODS: This multicenter, randomized study consisted of 2 weeks of screening, 8 weeks of double-blind treatment, and 6 weeks of treatment-free follow-up (OD allowed). Adult patients were randomized to 10 mg rupatadine OD or 10 mg rupatadine daily. At Week 4, if patients did not have a complete response, they switched from 10 to 20 mg rupatadine daily or underwent sham updosing (patients on 10 mg rupatadine OD). The primary aim was to compare CSU disease activity at the end of follow-up between daily versus OD. Additionally, we assessed the efficacy of rupatadine updosing. Major outcomes were disease activity, CSU-related quality of life (QoL), and disease control. RESULTS: At Week 4, disease activity and QoL significantly improved in daily versus OD-treated patients. Updosing of rupatadine did not improve the mean disease activity, but the number of complete responders increased during updosing from 5% to 22%. At the end of follow-up, the disease activity of patients treated OD versus daily was not significantly different. CONCLUSIONS: Daily rupatadine treatment significantly improved CSU disease activity and QoL during treatment versus OD treatment but not after discontinuation of rupatadine, indicating the benefits of a daily maintenance nsAH schedule.

Targeting histamine receptor 4 in cholinergic urticaria with izuforant (LEO 152020): results from a phase IIa randomized double-blind placebo-controlled multicentre crossover trial.

BACKGROUND: Cholinergic urticaria (CholU) is a common subtype of chronic inducible urticaria, where signs and symptoms (e.g. pruritic wheals and angioedema) are triggered by sweating due to physical exercise, passive warming and by other sweat-inducing situations. While guidelines recommend treatment with second-generation H1 antihistamines, approximately 90% of patients report uncontrolled disease. Targeting the histamine 4 receptor (H4R) has shown promise in preclinical/clinical studies of allergic/inflammatory diseases. Izuforant (LEO 152020) is a selective oral H4R antagonist with expected dual antipruritic and anti-inflammatory effects. OBJECTIVES: To assess the effects of izuforant in adults with CholU, a common type of chronic urticaria driven by histamine and characterized by high skin levels of H4R expression. METHODS: This was a phase IIa randomized double-blind placebo-controlled multicentre crossover trial where patients with CholU with an inadequate response to ≥ 1 standard dose of H1 antihistamine received izuforant 100 mg twice daily or placebo (EUCTR2020-004961-38-DE; NCT04853992). The primary endpoint was change from baseline in Urticaria Activity Score. Exploratory endpoints included CholU activity score over 7 days, urticaria control test, Physician Global Assessment, patient global assessment of severity (PGA-S), provocation tests, Dermatology Life Quality Index and CholU quality of life (CholU-QoL). Pharmacokinetic and pharmacodynamic parameters, and serum biomarkers were assessed, as well as safety and tolerability. RESULTS: Nineteen patients were randomized and included in the full analysis set; 18 completed treatment [mean (SD) age 29.5 (9.8) years; mean (SD) CholU duration 8.0 (6.3) years]. The primary and most of prespecified exploratory endpoints were not met; there were significant improvements in PGA-S for izuforant vs. placebo (P = 0.02), and nonsignificant improvements for other endpoints in quality of life and histamine skin prick test. All adverse events (AEs) experienced with izuforant were considered mild. The most frequently reported (> 1 patient) were nausea (three patients) and upper abdominal pain (two patients), occurring more frequently with izuforant vs. placebo (one patient each). There were no treatment-related serious AEs and no patient receiving izuforant discontinued the study. Treatment with izuforant did not cause downregulation of H4R. CONCLUSIONS: This is the first study to explore the role of H4R as a therapeutic target in urticaria. Targeting H4R with izuforant was well tolerated but did not demonstrate significant improvements vs. placebo in the primary endpoint and all but one prespecified exploratory endpoint in CholU.

Cholinergic urticaria (CholU) is a common subtype of an inflammatory skin condition called chronic inducible urticaria, where signs and symptoms (e.g. hives and swelling in the skin) are triggered by sweating caused by physical exercise, passive warming and other sweat-inducing situations. While guidelines recommend treatment with second-generation H1 antihistamines (a type of medication), approximately 90% of people with the condition report that these medications do not control the disease. Targeting the histamine 4 receptor (H4R) has shown promise in studies of allergic/inflammatory diseases. CholU is driven by histamine (a chemical released in the body) and characterized by high skin levels of H4R. Izuforant is a medication that may reduce itch and inflammation. In our study, which was carried out across multiple sites in Germany, we assessed the effects of izuforant 100 mg in 18 patients with CholU using a range of measures covering symptom control, disease severity, provocation response and quality of life. The primary endpoint (the main result measured at the end of the study to see if the treatment worked) was change from baseline in the post-provocation Urticaria Activity Score, where areas of skin were provoked and the time until common symptoms of CholU appeared (sweating and whealing (hives)) was measured. Overall, the primary endpoint and most of the exploratory endpoints were not met. There were significant improvements in patients' global assessment for izuforant versus placebo. This was the first study to explore the role of H4R as a therapeutic target in urticaria. Our findings suggest that targeting H4R with izuforant was well tolerated but did not demonstrate significant improvements versus placebo in the primary endpoint, and all but one prespecified exploratory endpoint in CholU.

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.

Chronic spontaneous urticaria (CSU) is a common disease characterized by hives, itching and inflammation (swelling) of the skin. CSU is mainly driven by what we call 'mast cells'. 'Eosinophils' are a type of white blood cell that protect the body from infections and allergens. These cells are abundant in skin biopsy samples of people with CSU, especially in the hives that contribute to swelling. Therefore, we thought that reducing eosinophils would be beneficial for treating CSU. Benralizumab is a drug that has been shown to reduce eosinophils in other diseases. This study, called 'ARROYO', was a 24-week clinical trial that compared benralizumab treatment with a placebo (inactive medicine) in adults with CSU who were taking antihistamines. We aimed to determine whether benralizumab would improve symptoms of CSU over time. Several assessments were used to measure changes in CSU symptoms, including hives, severity of itchiness, swelling of the skin, and other aspects related to overall psychological and physical wellbeing. The characteristics of the 155 people who took part in this study were consistent with what was expected for patients with CSU. We found that while benralizumab reduced eosinophil levels in people with CSU, there were no differences in symptoms in people receiving benralizumab compared with those receiving placebo. There were no new safety concerns related to benralizumab and no deaths. Overall, although benralizumab is effective at reducing the number of eosinophils, it is not effective at treating the symptoms of CSU. More studies are needed to uncover potential treatment targets in CSU.

The 7-day recall period version of the Urticaria Control Test-UCT7.

BACKGROUND: The Urticaria Control Test (UCT) is a well-established, very easy to use and calculate 4-item patient-reported outcome measure to assess chronic urticaria disease control during the previous 4 weeks. Clinical trials and practice may benefit from the use of a UCT version with a shorter recall period, but this does not exist. OBJECTIVES: We sought to develop and validate a UCT version with a 7-day recall period, the UCT7. METHODS: The UCT7 was developed, based on the UCT, and tested, in 152 patients with chronic urticaria (spontaneous: n = 101, inducible: n = 51) for its reliability, validity and screening accuracy, and clinimetric properties, in other words, the cutoff for well-controlled disease and the minimal clinically important difference. RESULTS: The UCT7 showed excellent internal consistency reliability with a Cronbach αvalue of 0.91 and test-retest reliability with an intraclass correlation coefficient of 0.83. Convergent validity was high and strongly correlated with anchors of disease control, wheal and angioedema frequency, and urticaria-related quality of life impairment. The UCT7 showed excellent sensitivity to change; however, changes in angioedema activity and impact did not correlate well with changes in UCT7. Based on receiver-operating characteristic curve analysis, the proportion of correctly classified patients, and patients' assessment of treatment efficacy, we recommend a cutoff value of 12 points for identifying patients with well-controlled disease. The UCT7 minimal clinically important difference for improvement was estimated to be 2 points. CONCLUSIONS: The UCT7 is a validated 7-day recall period version of the UCT. It is ideal for the assessment of disease control at short intervals in patients with chronic urticaria in clinical studies and practice.

Anti-KIT antibody, barzolvolimab, reduces skin mast cells and disease activity in chronic inducible urticaria.

BACKGROUND: Chronic inducible urticaria (CIndU) is characterized by mast cell (MC)-mediated wheals in response to triggers: cold in cold urticaria (ColdU) and friction in symptomatic dermographism (SD). KIT receptor activation by stem cell factor (SCF) is essential for MC function. Barzolvolimab (CDX-0159) is a humanized antibody that inhibits KIT activation by SCF and was well tolerated in healthy volunteers with dose-dependent plasma tryptase suppression indicative of systemic mast cell ablation. METHODS: This is an open-label, trial in patients with antihistamine refractory ColdU or SD, receiving one IV dose of barzolvolimab (3 mg/kg), with a 12-week follow-up. Primary endpoint was safety/tolerability; pharmacodynamic (PD)/clinical endpoints included serum tryptase, plasma SCF, skin MC histology, provocation tests, urticaria control test (UCT), and dermatology life quality index (DLQI). RESULTS: Analysis populations were safety (n = 21) and pharmacodynamics/clinical activity (n = 20). Barzolvolimab was well tolerated; most adverse events were mild and resolved. Treatment resulted in significant depletion of skin MCs, decreased tryptase (

Efficacy of Concentrated Heat for Treatment of Insect Bites: A Real-world Study.

Insect bites that cause itch, pain and swelling are very common. The use of concentrated heat for relief of these symptoms may be a promising approach; however, the scientific evidence for efficacy of hyperthermia treatment is sparse. We report here the results of a large real-world study using a randomized control group to assess the efficacy of hyperthermia on insect bites in real-world conditions, specifically considering mosquito bites as the most common type. The study was conducted in a decentralized manner via a smartphone-controlled medical device, heat it®, for treatment of insect bites and stings through application of heat. The application that controls the device was accompanied by additional questionnaires, that collected data related to insect bites, such as itch and pain intensity. Analysis of data from over 12,000 collected treated insect bites, generated by approximately 1,750 participants (42% female, 39 ± 13 years) showed significant inhibition of itch and pain for all investigated insect species (mosquitoes, horseflies, bees and wasps). Mosquito bite-induced itch was reduced by 57% within the first minute and by 81% 5-10 min after treatment, and the overall reduction in itch and pain was more pronounced than in the control group. In conclusion, the results indicate that local application of heat relieves symptoms of insect bites.

Autoimmune chronic spontaneous urticaria.

Chronic spontaneous urticaria (CSU) is a debilitating mast cell-driven disease characterized by recurrent wheals and/or angioedema. Substantial progress has been made in dissecting the 2 main autoimmune mechanisms that drive the pathogenesis of CSU. Type I autoimmune (autoallergic) CSU is associated with IgE antibodies against autoantigens, for example, thyroid peroxidase and IL-24. Type IIb autoimmune CSU is mediated by autoantibodies that activate mast cells, for example, via IgE and FcεRI, and is present in less than 10% of patients with CSU when strict criteria are used, that is, triple positivity of autologous serum skin test, immunoassays for IgG autoantibodies, and basophil activation tests. A subpopulation of patients with CSU has both types. Type IIb autoimmune CSU is characterized by higher disease severity, concomitant autoimmune diseases, low levels of total IgE, elevated levels of IgG-anti-thyroid peroxidase, basopenia, eosinopenia, poor response to antihistamines and to omalizumab, and a good response to cyclosporine. Novel targeted therapies for CSU are under development such as ligelizumab, an anti-IgE, fenebrutinib and remibrutinib, Bruton's tyrosine kinase inhibitors, and dupilumab, an anti-IL-4Rα. Further studies should investigate the overlap between autoallergic and type IIb autoimmune CSU, optimize the diagnosis of both autoimmune endotypes using easy-to-perform, noninvasive, and inexpensive markers, and assess differences in response to therapy.

Mast cells, cortistatin, and its receptor, MRGPRX2, are linked to the pathogenesis of chronic prurigo.

BACKGROUND: Chronic prurigo (CPG) is characterized by intensive itch and interactions among nerves, neuropeptides, and mast cells (MCs). The role of some neuropeptides such as cortistatin (CST) and its receptor, Mas-related G protein-coupled receptor X2 (MRGPRX2), in CPG remains poorly investigated. OBJECTIVES: We evaluated first whether CST activates human skin MCs, and second whether CST and MRGPRX2 are expressed in the skin of CPG patients, and by which cells. METHODS: Skin prick tests and microdialysis with CST were performed in 6 and 1 healthy volunteers, respectively. Degranulation of human skin MCs was assessed using ß-hexosaminidase and histamine release assays. Skin samples from 10 patients with CPG and 10 control subjects were stained for CST, MCs, and MRGPRX2 (protein and mRNA) using immunohistochemistry, immunofluorescence, and/or in situ hybridization. Flow cytometry was used to assess CST in human skin MCs. MRGPRX2 levels were measured in serum by ELISA. RESULTS: CST induced concentration-dependent degranulation of human skin MCs in vivo and ex vivo. Skin lesions of CPG patients exhibited markedly higher numbers of CST-expressing cells, CST-expressing MCs, MRGPRX2-expressing cells, and MRGPRX2 mRNA-expressing cells than nonlesional skin. MCs were the main MRGPRX2 mRNA-expressing cells in the lesions of most CPG patients (70%). Stimulation of human skin MCs with anti-IgE led to a release of CST. The number of MRGPRX2-expressing cells correlated with disease severity (r = 0.649, P = .04). MRGPRX2 serum levels in CPG patients correlated with disease severity (r = 0.704, P = .023) and quality-of-life impairment (r = 0.687, P = .028). CONCLUSIONS: CST and MRGPRX2 may contribute to the pathogenesis of CPG and should be evaluated in further studies as potential biomarkers and novel therapeutic targets.

Chronic urticaria and the pathogenic role of mast cells.

The signs and symptoms of chronic urticaria (CU) are caused by the activation and degranulation of skin mast cells (MCs). Recent studies have added to our understanding of how and why skin MCs are involved and different in CU. Also, novel and relevant mechanisms of MC activation in CU have been identified and characterized. Finally, the use of MC-targeted and MC mediator-specific treatments has helped to better define the role of the skin environment, the contribution of specific MC mediators, and the relevance of MC crosstalk with other cells in the pathogenesis of CU. Here, we review these recent findings and their impact on our understanding of CU, with a focus on chronic spontaneous urticaria (CSU). Also, we highlight open questions, issues of controversy, and unmet needs, and we suggest what studies should be performed moving forward.

CRUSE - What the first 100 days have taught us.

Introduction: Health apps play an increasing role in everyday healthcare, especially for chronic diseases. The Chronic Urticaria Self Evaluation (CRUSE) is a new mobile health app for chronic spontaneous urticaria (CSU) patients, which replaces disease tracking via paper and pen, thus making disease monitoring more convenient, increasing tracking compliance, and improving data quality and access. Methods: CRUSE enables patients to complete patient-reported outcome measures on their smartphone and send the results, along with current medication and pictures, to their treating physician via email. CRUSE captures the urticaria (UAS) and angioedema activity (AAS) scores and the urticaria and angioedema control tests (UCT and AECT). In this work, a descriptive analysis of CRUSE users and reported days was performed. The global network of Urticaria Centers of Reference and Excellence (UCARE) provides the app and its data. Results: CRUSE is now available in Germany, Switzerland, Austria, the UK, Italy, Spain, France, and Turkey. Of 620 newly registered users (from July 1st until November 18th of 2022), 72 % were female, and the mean age was 36.6 years (17 - 78 years). The average daily UAS and AAS value (mean ± standard deviation) were 2.1 ± 1.9 and 7.2 ± 3.3, respectively. Most CRUSE patients had poorly controlled disease, with mean UCT values of 7.0 ± 4.4 and mean AECT values of 8.1 ± 4.5. Conclusion: The first days of patients with CSU using CRUSE confirm the high need for an app that helps to monitor disease activity, impact, and control. The first results indicate low levels of disease control in most CRUSE users, with low UCT and AECT values. Future analyses will assess follow-up documentation data and evaluate the effects of treatment changes on CSU activity, impact, and control.

Ligelizumab for Chronic Spontaneous Urticaria.

BACKGROUND: In the majority of patients with chronic spontaneous urticaria, most currently available therapies do not result in complete symptom control. Ligelizumab is a next-generation high-affinity humanized monoclonal anti-IgE antibody. Data are limited regarding the dose-response relationship of ligelizumab and the efficacy and safety of ligelizumab as compared with omalizumab and placebo in patients who have moderate-to-severe chronic spontaneous urticaria that is inadequately controlled with H1-antihistamines at approved or increased doses, alone or in combination with H2-antihistamines or leukotriene-receptor antagonists. METHODS: In a phase 2b dose-finding trial, we randomly assigned patients to receive ligelizumab at a dose of 24 mg, 72 mg, or 240 mg, omalizumab at a dose of 300 mg, or placebo, administered subcutaneously every 4 weeks for a period of 20 weeks, or a single 120-mg dose of ligelizumab. Disease symptoms of hives, itch, and angioedema were monitored by means of weekly activity scores. The main objective was to determine a dose-response relationship for the complete control of hives (indicated by a weekly hives-severity score of 0, on a scale from 0 to 21, with higher scores indicating greater severity); the primary end point of this response was assessed at week 12. Complete symptom control was indicated by a weekly urticaria activity score of 0 (on a scale from 0 to 42, with higher scores indicating greater severity). Safety was analyzed throughout the trial. RESULTS: A total of 382 patients underwent randomization. At week 12, a total of 30%, 51%, and 42% of the patients treated with 24 mg, 72 mg, and 240 mg, respectively, of ligelizumab had complete control of hives, as compared with 26% of the patients in the omalizumab group and no patients in the placebo group. A dose-response relationship was established. At week 12, a total of 30%, 44%, and 40% of the patients treated with 24 mg, 72 mg, and 240 mg, respectively, of ligelizumab had complete control of symptoms, as compared with 26% of the patients in the omalizumab group and no patients in the placebo group. In this small and short trial, no safety concerns regarding ligelizumab or omalizumab emerged. CONCLUSIONS: A higher percentage of patients had complete control of symptoms of chronic spontaneous urticaria with ligelizumab therapy of 72 mg or 240 mg than with omalizumab or placebo. (Funded by Novartis Pharma; ClinicalTrials.gov number, NCT02477332.).

Sustained safety and efficacy of ligelizumab in patients with chronic spontaneous urticaria: A one-year extension study.

BACKGROUND: Ligelizumab, a next-generation, humanized anti-immunoglobulin E (IgE) monoclonal antibody is in development as a treatment for patients with chronic spontaneous urticaria, whose symptoms are inadequately controlled with standard-of-care therapy. OBJECTIVE: To evaluate the long-term safety and re-treatment efficacy of ligelizumab 240 mg in patients who completed the core study and extension study. METHODS: This open-label, single-arm, long-term Phase 2b extension study was designed to assess patients who were previously administered various doses of ligelizumab, omalizumab or placebo in the Phase 2b, dose-finding core study and who presented with active disease after Week 32. In the extension study, patients received ligelizumab 240 mg subcutaneously every 4 weeks, for 52 weeks and were monitored post-treatment for 48 weeks. RESULTS: Overall, ligelizumab was well-tolerated with no newly identified safety signals. A total of 95.4% (226/237) screened patients received ligelizumab 240 mg in the extension study; 84.1% (190/226) of patients experienced at least one treatment-emergent adverse event. Most reported events were mild (41.6%) or moderate (35.8%) and mostly unrelated to the study treatment. At Week 12, 46.5% of patients had a complete response increasing to 53.1% after 52 weeks. Following 52 weeks of extension study treatment, 75.8% (95% confidence interval, 69.9, 81.3) of patients had cumulative complete responses. The median time to relapse in complete responders was 38 weeks. CONCLUSION: The long-term safety profile of ligelizumab 240 mg in patients with chronic spontaneous urticaria was consistent with the core study and re-treatment efficacy was shown. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02477332 and NCT02649218.

The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria.

This update and revision of the international guideline for urticaria was developed following the methods recommended by Cochrane and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. It is a joint initiative of the Dermatology Section of the European Academy of Allergology and Clinical Immunology (EAACI), the Global Allergy and Asthma European Network (GA²LEN) and its Urticaria and Angioedema Centers of Reference and Excellence (UCAREs and ACAREs), the European Dermatology Forum (EDF; EuroGuiDerm), and the Asia Pacific Association of Allergy, Asthma and Clinical Immunology with the participation of 64 delegates of 50 national and international societies and from 31 countries. The consensus conference was held on 3 December 2020. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS). Urticaria is a frequent, mast cell-driven disease that presents with wheals, angioedema, or both. The lifetime prevalence for acute urticaria is approximately 20%. Chronic spontaneous or inducible urticaria is disabling, impairs quality of life, and affects performance at work and school. This updated version of the international guideline for urticaria covers the definition and classification of urticaria and outlines expert-guided and evidence-based diagnostic and therapeutic approaches for the different subtypes of urticaria.

A beneficial role for immunoglobulin E in host defense against honeybee venom.

Allergies are widely considered to be misdirected type 2 immune responses, in which immunoglobulin E (IgE) antibodies are produced against any of a broad range of seemingly harmless antigens. However, components of insect venoms also can sensitize individuals to develop severe IgE-associated allergic reactions, including fatal anaphylaxis, upon subsequent venom exposure. We found that mice injected with amounts of honeybee venom similar to that which could be delivered in one or two stings developed a specific type 2 immune response that increased their resistance to subsequent challenge with potentially lethal amounts of the venom. Our data indicate that IgE antibodies and the high affinity IgE receptor, FcεRI, were essential for such acquired resistance to honeybee venom. The evidence that IgE-dependent immune responses against venom can enhance survival in mice supports the hypothesis that IgE, which also contributes to allergic disorders, has an important function in protection of the host against noxious substances.

The Classification, Pathogenesis, Diagnostic Workup, and Management of Urticaria: An Update.

Wheals and angioedema are the signature signs of urticaria, and itch is the key symptom. Urticaria, in most patients, is acute and resolves within days (acute urticaria, AU). Chronic urticaria (CU) can be of long duration and results not only in severely impaired quality of life but also has a socioeconomic impact due to work productivity impairment. In some patients with CU, the wheals and angioedema are induced exclusively by defined and definite triggers (chronic inducible urticaria, CIndU). In most patients with CU, wheals and angioedema develop unprompted, spontaneously (chronic spontaneous urticaria, CSU). The management of CU aims for the complete control and absence of its signs and symptoms. This is achieved, in most patients, by prophylactic treatment until spontaneous remission occurs. Modern, second-generation H1-antihistamines are the first-line therapy, with the option of updosing to fourfold, and omalizumab is used when this fails.

Mas-related G protein-coupled receptor X2 and its activators in dermatologic allergies.

The Mas-related G protein-coupled receptor X2 (MRGPRX2) is a multiligand receptor responding to various exogenous and endogenous stimuli. Being highly expressed on skin mast cells, MRGPRX2 triggers their degranulation and release of proinflammatory mediators, and it promotes multicellular signaling cascades, such as itch induction and transmission in sensory neurons. The expression of MRGPRX2 by skin mast cells and the levels of the MRGPRX2 agonists (eg, substance P, major basic protein, eosinophil peroxidase) are upregulated in the serum and/or skin of patients with inflammatory and pruritic skin diseases, such as chronic spontaneous urticaria or atopic dermatitis. Therefore, MRGPRX2 and its agonists might be potential biomarkers for the progression of cutaneous inflammatory diseases and the response to treatment. In addition, they may represent promising targets for prevention and treatment of signs and symptoms in patients with skin diseases or drug reactions. To assess this possibility, this review explores the role and relevance of MRGPRX2 and its activators in cutaneous inflammatory disorders and chronic pruritus.

A group of cationic amphiphilic drugs activates MRGPRX2 and induces scratching behavior in mice.

BACKGROUND: Mas gene-related G protein-coupled receptors (MRGPRs) are a G protein-coupled receptor family responsive to various exogenous and endogenous agonists, playing a fundamental role in pain and itch sensation. The primate-specific family member MRGPRX2 and its murine orthologue MRGPRB2 are expressed by mast cells mediating IgE-independent signaling and pseudoallergic drug reactions. OBJECTIVES: Our aim was to increase knowledge about the function and regulation of MRGPRX2/MRGPRB2, which is of major importance in prevention of drug hypersensitivity reactions and drug-induced pruritus. METHODS: To identify novel MRGPR (ant)agonists, we screened a library of pharmacologically active compounds by utilizing a high-throughput calcium mobilization assay. The identified hit compounds were analyzed for their pseudoallergic and pruritogenic effects in mice and human. RESULTS: We found a class of commonly used drugs activating MRGPRX2 that, to a large extent, consists of antidepressants, antiallergic drugs, and antipsychotics. Three-dimensional pharmacophore modeling revealed structural similarities of the identified agonists, classifying them as cationic amphiphilic drugs. Mast cell activation was investigated by using the 3 representatively selected antidepressants clomipramine, paroxetine, and desipramine. Indeed, we were able to show a concentration-dependent activation and MRGPRX2-dependent degranulation of the human mast cell line LAD2 (Laboratory of Allergic Diseases-2). Furthermore, clomipramine, paroxetine, and desipramine were able to induce degranulation of human skin and murine peritoneal mast cells. These substances elicited dose-dependent scratching behavior following intradermal injection into C57BL/6 mice but less so in MRGPRB2-mutant mice, as well as wheal-and-flare reactions following intradermal injections in humans. CONCLUSION: Our results contribute to the characterization of structure-activity relationships and functionality of MRGPRX2 ligands and facilitate prediction of adverse reactions such as drug-induced pruritus to prevent severe drug hypersensitivity reactions.