Investigators have initiated the first randomized controlled trial examining whether extending the dosing interval of omalizumab from 4 to 6 weeks can maintain disease control in chronic spontaneous urticaria.
The EXtending Omalizumab Treatment Intervals in patients with chronic spontaneous urticaria (CSU) (EXOTIC) trial, published in BMJ Open, is a multicenter, open-label, non-inferiority study comparing standard 4-week dosing to extended 6-week dosing in patients who achieve disease control with initial therapy.
"Should our hypothesis be confirmed that omalizumab administered Q6W is non-inferior to omalizumab administered Q4W in maintaining disease control, it could have significant impact on future treatment regimens," the investigators, led by Ditte Georgina Zhang, wrote. "This validation may enhance cost-effectiveness of omalizumab and spare patients of unnecessary injections and hospital visits."
The trial began enrolling in January 2024 and has randomized 11 of 39 recruited patients as of October 8, 2024. Investigators aim to complete recruitment by August 2025.
Participants who achieve a Urticaria Control Test score of 12 or greater after 12 weeks of standard omalizumab therapy (300 mg every 4 weeks) will be randomized to continue standard dosing or switch to extended 6-week intervals. Both arms will be followed for 36 weeks.
The primary endpoint is the absolute difference in average UCT scores between arms at week 36. Secondary outcomes include differences in quality-of-life measures and the proportion of patients maintaining disease control.
A total of 40 patients (20 per arm) will be enrolled to allow for a 20% dropout rate. This sample size provides 80% power to reject the null hypothesis that extended dosing is inferior, using a non-inferiority margin of 19% (corresponding to a 3-point UCT score difference).
Danish regulatory authorities approved the study, which is registered at ClinicalTrials.gov (NCT05916937). Conflicts of interest are available in the published study.
