Omalizumab in Chronic Spontaneous Urticaria (CSU): Real-Life Experience in Dose/Interval Adjustments and Treatment Discontinuation

Background Data on real-life experience with omalizumab dose/interval adjustments is still limited, as well as on omalizumab discontinuation. Objective To evaluate efficacy and safety of omalizumab dose/interval adjustment in a Portuguese cohort of chronic spontaneous urticaria (CSU) patients and to characterize those who discontinued omalizumab. Methods Retrospective study of patients who started omalizumab for CSU at a Portuguese UCARE, between 2009-2021. Response criteria was based on a weekly Urticaria Activity Score (UAS7) <7 points (partial: UAS7 7-15 points; non-responders: UAS7>15 points; minimal important difference (MID) >10 points). Results Total of 138 patients, 83% women, median age 49 years (IQR 40-58). On 300mg q4 weeks, 96 patients (70%) were responders, 29 (21%) partial responders and 13 (9%) non-responders. After dose/interval adjustaments (up to 600mg q2 weeks), 108 (78%) were responders, 27 (20%) partial responders and 3 (2%) non-responders. No adverse events were reported. Updosing was more frequent in patients with angioedema, BMI>30Kg/m2, positive basophil activation test and autologous serum test. 71 patients (51%) lengthened interval, presenting higher median pre-omalizumab D-dimer (0.2 vs 0 mcg/mL, p 0.038) and CRP (0.3 vs 0.1mg/dL, p 0.030) values than those with standard dose. 37 patients (27%) stopped omalizumab, but 14(38%) of them needed re-treatment, on average 11 months after discontinuation. Patients with angioedema and longer omalizumab duration had higher chance of relapse. Conclusion Omalizumab dose and/or interval adjustment is effective and safe and should be implemented in partial/non-responders for response improvement, and in responders for further discontinuation. A protocol for regimen adjustments is proposed.