Mepolizumab for the Treatment of Chronic Spontaneous Urticaria

This is an open-label, single arm exploratory study of mepolizumab in the treatment of CSU. The primary endpoint will be the mean reduction in the seven day urticaria activity score (UAS7) before and after 10 weeks of treatment with mepolizumab. Secondary endpoints will be the mean reduction of the urticaria control test (UCT) score and the weekly itch severity score (ISS) before and after treatment. Enrollment examination will include a standardized history and examination, baseline UCT score, CBC with differential, serum IgE level, chronic urticaria index, IgE Fc receptor antibody functional assay, and a 4 mm punch biopsy of lesional skin to confirm the urticarial tissue reaction includes eosinophils and is not neutrophilic predominant. Patients will discontinue all anti-histamines and start cetirizine 10 mg PO BID which may be continued throughout the study duration. Patients will be provided with a log book to track daily urticaria signs and symptoms in a standardized manner for UAS scoring. At week 0 (enrollment visit +7 days), baseline UAS7 and ISS score will be assessed and skin biopsy results reviewed. Patients with a confirmatory skin biopsy will receive 200 mg SC of mepolizumab at week 0,2,4,6,and 8. UAS-7 and weekly ISS score will be calculated at week 0, 4, 8, and 10. UCT scoring will be calculated at week 0 and at week 10. Repeat CBC with differential, serum IgE level, and measures of basophil serum activation (chronic urticaria index, IgE FC Receptor antibody functional assay) will be assessed at week 10. Attached to this document is a protocol summary.