Autoimmune Phenotype in Refractory Chronic Urticaria Does Not Affect Response to Omalizumab

Abstract

FEBRUARY 2013 AB30 Abstracts S A T U R D A Y 108 Autoimmune Phenotype in Refractory Chronic Urticaria Does Not Affect Response to Omalizumab Ravi K. Viswanathan,MD, Sameer K. Mathur, MD, PhD, FAAAAI; University ofWisconsin School of Medicine and Public Health, Madison, WI, William S. Middleton Veterans Hospital, Madison, WI. RATIONALE: Omalizumab has been shown to be efficacious in refractory (2-4x H1/H2 +/LTRA +/immunomodulator) chronic idiopathic urticaria (CIU) patients in numerous reports. However, it remains unknown whether there are specific phenotypes of CIU that are more responsive to omalizumab therapy.We sought to address this by characterizing a series of CIU patients who have undergone omalizumab therapy and their response patterns. METHODS: A retrospective chart-review analysis of CIU patients treated with omalizumab at the University of Wisconsin Allergy Clinic was performed with particular focus on their autoimmune characteristics, response to therapy, and dosing/duration parameters. RESULTS: We analyzed 13 refractory CIU patients (12/13 previously used >5 1 immunomodulator) treated with omalizumab and observed an overall response rate of 92% (11/12, 1 unknown) to its usage. Of these 11 responders, 5 patients (45%) had a complete response and 6 patients (55%) had a partial response. Seven patients were categorized as ‘‘autoimmune’’ (presence of 1 positive autoimmune biomarker) with 3 patients (43%) demonstrating complete response and 4 patients (57%) showing partial response to omalizumab therapy. Among the five patients categorized as ‘‘non-autoimmune, two (40%) reported a complete response, two (40%) had a partial response, and one (20%) had no response. The mean duration of therapy for all patients was 4.83 months with cumulative doses ranging from 300mg every 4 weeks to 600mg every 4 weeks. CONCLUSIONS: Our retrospective analysis suggests that omalizumab appears to demonstrate robust efficacy in refractory CIU patients regardless of their autoimmune status with similar dosing and duration parameters.