P093 Bespoke omalizumab prescribing in chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) represents the most common form of chronic urticaria and is estimated to affect 0.5–1% of the worldwide population. This condition has an underestimated but significant impact on the quality of life of patients. It represents a high socioeconomic burden to healthcare systems due to its chronic nature and the challenges currently faced in its treatment. Omalizumab is the only IgE-targeted biologic currently approved for patients with CSU who have persistent symptoms despite high-dose antihistamines. The licensed dose for omalizumab is 300 mg every 4 weeks and it is currently recommended for 6 months; however, it is estimated that approximately 30% of patients do not respond to this standardized regimen and there is currently no clear guidance on managing this cohort of patients. This study provides an overview of our clinical practice when prescribing omalizumab for the management of CSU and further evidence of the efficacy of a personalized dosing regimen. We report on 36 patients started on omalizumab during the year 2022 from five separate dermatology centres. Data were collected retrospectively from pharmacy records using data spreadsheets. Twenty-seven patients were given omalizumab for the first time, while nine patients were on their second course. Dosing and treatment intervals were adjusted according to disease activity using the Urticaria Activity Score (UAS7). Eleven patients received personalized dosing, with their dose titrated up or down based on symptom control. Three patients required updosing to 450 mg 4-weekly, one patient was given 600 mg 4-weekly, one patient had their dose titrated down to 150 mg monthly, and six patients remained on 300 mg 4-weekly beyond 6 months. Our results suggest that 30.5% of patients would have had to discontinue treatment and consider switching to ciclosporin had personalized dosing not been considered. Immunosuppression comes with its challenges, with significant adverse events, rigorous blood monitoring and more frequent hospital reviews all contributing to the ever-increasing financial burden on the NHS. Omalizumab, in comparison, is better tolerated and carries a much better safety profile. This study also supports findings from a proportion of patients will require longer treatment courses, as a reduction in UAS7 scores may occur beyond the fourth dose. Overall, 25% of patients were on their second course of treatment at the time of analysis, suggesting a lack of remission at 6 months and the need for more guidance on longer-term treatment.