The following is a summary of “Predicting responses to omalizumab in antihistamine-refractory chronic urticaria: A real-world longitudinal study,” published in the May 2024 issue of Allergy & Immunology by Lee, et al.

Managing chronic urticaria (CU) that does not respond to H1-antihistamines (H1AHs) is challenging, and the real-world efficacy of omalizumab remains uncertain. For a study, researchers sought to evaluate the real-world effectiveness of omalizumab, determine the optimal timing for assessing response, and identify predictive factors for treatment outcomes.

Initially, 5,535 patients with CU receiving at least 20 mg of loratadine daily for a minimum of 6 months (from January 2007 to August 2021) were screened. Ultimately, 386 patients who had been on omalizumab add-on treatment for over 6 months were followed for more than 2 years. A generalized linear model was used to identify predictors of treatment response to omalizumab in patients with antihistamine-refractory CU.

In the retrospective cohort, omalizumab treatment resulted in cumulative response rates of 55.2% at 3 months, 71.0% at 6 months, and 81.4% at 9 months for patients with H1AH-refractory CU. Analysis of longitudinal responses identified three distinct clusters: favorable (cluster 1 [n = 158]), intermediate (cluster 2 [n = 143]), and poor responses (cluster 3 [n = 85]). Patients were further categorized based on achieving complete response within 3 months, identifying 213 early responders, 117 late responders, and 56 nonresponders. Initial doses of omalizumab varied significantly among the clusters. A low total IgE level (<40 kU/L) was a predictor of nonresponse (odds ratio [OR] = 3.10 [P = .018]). Early responders were associated with a higher initial omalizumab dose (≥300 mg) (OR = 2.07 [P = .016]), higher basophil counts (OR = 2.0 [P = .014]), total IgE levels exceeding 798 kU/L (OR = 0.37 [P = .047]), and a lower platelet-to-lymphocyte ratio (OR = 0.50 [P = .050]).

Real-world data indicated three distinct response clusters to omalizumab treatment, confirming that a low serum total IgE level (<40 kU/L) predicts nonresponse, and suggested potential biomarkers for early responders, including IgE levels, basophil count, and platelet-to-lymphocyte ratio.

Reference: jaci-global.org/article/S2772-8293(24)00041-9/fulltext