Published Online: October 16, 2015
Chronic idiopathic/spontaneous urticaria (CIU/CSU) is a rare condition, in which itchy hives, with or without angioedema, last for at least 6 weeks without a recognizable trigger. If CIU/CSU persists despite usual treatment with antihistamines, omalizumab (an antibody to immunoglobulin E (IgE)) may help alleviate symptoms. Patient and practicing clinicians need to understand when to expect the onset of response to treatment with omalizumab in CIU/CSU.
To report timing to and duration of response to omalizumab in CIU/CSU, Kaplan, et al analyzed data from three large (975 patients total), randomized clinical trials. These trials evaluated the efficacy and safety of omalizumab in patients with CIU/CSU. Two studies (ASTERIA I and ASTERIA II) enrolled CIU/CSU patients who remained symptomatic while taking antihistamines at usual recommended dosing. The third study (GLACIAL) included patients who continued to have symptoms, despite treatment with antihistamines up to 4 times the recommended dose, sometimes accompanied with other therapies (eg, cimetidine, famotidine, nizatidine, ranitidine, montelukast, or zafirlukast). Patients were injected omalizumab (75 mg, 150 mg, or 300 mg) or placebo every 4 weeks. Using an electronic diary twice daily, patients reported their CIU/CSU symptoms: the severity of itching and number of hives. Response in these analyses was defined as either complete (no hives and itching) or well-controlled symptoms (minimal hives or itching).
The results, recently published in The Journal of Allergy and Clinical Immunology (JACI), revealed that patients treated with omalizumab 300 mg showed the highest rate of both types of response. For example, after a single dose of omalizumab 300 mg, up to half of patients reported well-controlled symptoms and over one-fifth had a complete response. Some patients, who did not respond within the first 3 doses, responded with continued dosing (between 3 and 6 doses). Of the patients who responded, those treated with omalizumab 300 mg were most likely to continue to report their response throughout the study period.
Even though omalizumab 300 mg requires two injections, it is most likely to result in complete response or lead to well-controlled symptoms in CIU/CSU. If any of these responses are not achieved after the first omalizumab injection, the treatment should be continued, as some patients require more than one dose to demonstrate well-controlled urticaria or complete elimination of symptoms.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.