Predicting Responses to Omalizumab in Antihistamine-Refractory Chronic Urticaria
Young Min Ye (Suwon, République de Corée), Hyun Young Lee (Suwon-si, République de Corée), Youngsoo Lee (Suwon, République de Corée), Jaehyuk Jang (Suwon, République de Corée), Dong-Ho Nahm (Suwon, République de Corée), Hae-Sim Park (Suwon, République de Corée)
Background

Treating H1-antihistamine (H1AH)-refractory chronic urticaria (CU) is challenging, and the real-world effectiveness of omalizumab remains unclear. To evaluate the real-world effectiveness of omalizumab, optimal response assessment timing, and predictive factors, a retrospective longitudinal cohort was analyzed.

Method

Initially, 5,535 CU patients on ≥ 20 mg loratadine daily for ≥ 6 months (Jan 2007-Aug 2021) were screened; 386 patients receiving over 6 months of omalizumab add-on treatment and were assessed for more than 2 years. Predictors of treatment responses to omalizumab add-on therapy for H1AH refractory CU patients were identified using a generalized linear model.

Results

In this retrospective cohort, omalizumab treatment showed cumulative response rates of 55.2% at 3 months, 71.0% at 6 months, and 81.4% at 9 months for H1AH-refractory CU patients. Longitudinal responses to omalizumab treatment revealed three distinct clusters: favorable (cluster 1, n=158), intermediate (cluster 2, n=143), and poor responses (cluster 3, n= 85). Patients were categorized based on achieving a complete response within 3 months, identifying 213 early responders, 117 late responders, and 56 nonresponders. The initial dose of omalizumab differed significantly among the three clusters. Low total IgE (<40 kU/L) predicted non-response (OR=3.10, P=0.018). Early responders were associated with a higher initial omalizumab dose (≥300 mg, OR=2.07, P=0.016), higher basophil counts (OR=2.0, P=0.014), total IgE levels exceeding 798 kU/L (OR=0.37, P=0.047), and lower platelet-to-lymphocyte ratio (PLR, OR=0.50, P=0.050).

Conclusion

Real-world data reveal three distinct clusters for omalizumab treatment responses, confirm low serum total IgE (<40 kU/L) as a predictor of nonresponse, and identify potential biomarkers, including IgE, basophils, and PLR for early responders.

This work was supported by a grant from the National Research Foundation of Korea (NRF) funded by the Korea government (NRF-2022R1A2C2006607) and partly by a grant of the Korea Health Technology R&D Project(HR16C0001) through the Korean Health Industry Development Institute(KHIDI), funded by the Ministry of Health and Welfare.