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About
The aim of this study is to investigate the pathophysiological mechanism of omalizumab in patients with documented chronic urticaria who have complaints under standard antihistamine treatment. With this study the investigators will assess the correlation between Fc-IgE receptor downregulation as well as functionality and clinical response to omalizumab treatment in patients with chronic urticaria. This may be an approach for other diseases as well, where Fc-IgE receptor crosslinking are essential. The treatment time is set for a total of 4 monthly applications of omalizumab. According to the dosage recommendations of recent studies, fixed doses of 300 mg omalizumab are administered subcutaneously.
Full description
Background
Chronic urticaria (CU) is a frequent disease with a lifetime incidence of up to 25-30% of the population. Currently, CU treatment relies mainly on second generation antihistamines and is purely symptomatic. The disease tends to have a cyclical nature with spontaneous disappearance and frequent relapses. Some patients show a sufficient response to standard second generation antihistamines like (levo)cetirizine 10mg, (des)loratadine 5mg or terfenadine 120-180mg. Others need higher doses (up to 4-fold usual daily dose), often accompanied by sedation. Treatment may last for months, even years. If this first-line therapy is insufficient, the next step (sometimes even before use of excessively high doses of antihistamines) is to add first generation, even more sedating antihistamines, some of which have additional modes of action (e.g. anticholinergic effects in doxepin treatment). A considerable number of patients with CU need treatment escalations with leukotriene receptor blocking agents (e.g. montelukast), systemic corticosteroids (5-20mg prednisolon/d) or even cyclosporine (daily dose 3-5 mg/kg) or other immunosuppressive drugs used off-label. Such patients are often investigated more in detail to find an infection or autoimmune disease - often still without clear results.
Different clinical findings suggest that the mast cell system in many patients with CU is "overactive" with increased releasability. Minor stress like scratching can already induce degranulation resulting in wheal-and-flare skin reactions. Therefore, a therapy directly aiming at a decrease in this mast cell "hyperreleasability" would be optimal. Omalizumab binds selectively to free IgE in plasma, inhibits its binding to Fc-IgE receptor on the surface of mast cells and basophils and reduces the number of Fc-IgE receptors on basophils in atopic patients. Significant reduction of Fc-IgE receptor density on the surface of circulating basophils has been found as early as 1 week after administration of omalizumab. In contrast to this, the onset of clinical efficacy of omalizumab in asthma is considered to take place relatively late, namely about 4 months after start of treatment. The pathophysiologic concepts of omalizumab treatment in allergic asthma are focused on the neutralisation of IgE, and less on the Fc-IgE receptor density. In allergology, free IgE in plasma is only relevant regarding Fc-IgE receptor density on effector cells. Therefore, Fc-IgE receptor density measurement might be an important parameter for mast cell and basophil "releasability" and therefore a good in vitro surrogate marker for their reactivity. E.g. it is well known that only about 50% of IgE-sensitized individuals show clinically relevant allergic symptoms. This difference between sensitization and allergy may also be due to Fc-IgE receptor density on mast cells and basophils. Flowcytometric determination of Fc-IgE receptor density on the surface of basophils and additional testing for the functional consequences of a change in this density (ability to crosslink Fc-IgE receptors by autoantibodies and allergens) raise the possibility to evaluate this hypothesis - using omalizumab as a drug being able to decrease Fc-IgE receptor density:
Objective
Primary objectives
Secondary objectives
Change of responsiveness to Fc-IgE cross-linking dependent stimuli:
Measurement of IL-3 hyperresponsiveness of basophils after Stimulation with anti-IgE and allergen
Daily urticaria activity score
Medication and rescue medication use
German version of the Chronic Urticaria Quality of Life Questionnaire (CU-Q2oL)
Methods
This is a monocentric, double-blind, randomized placebo-controlled trial, which aims to investigate the pathophysiological mechanism of omalizumab in patients with documented chronic urticaria who have complaints under standard antihistamine treatment.
According to the inclusion criteria, 30 patients with diagnosed chronic urticaria will be recruited in our outpatient clinic. Omalizumab (Xolair®) is administered in fixed dose of 300 mg in a total of 4 monthly doses according to the reference. A follow-up visit is planned 2 months after the last injection.
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30 participants in 2 patient groups, including a placebo group
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Data sourced from clinicaltrials.gov
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