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.

Inclusion Criteria:

- Male and female patients 18 years or older.

- Clinical and/or histopathological diagnosis of conventional CSU

- Unresponsive to oral antihistamine therapy

- Good general health as confirmed by medical history

- Patients who are willing and capable of cooperating to the extent and degree required
by the protocol; and

- Patients who read and sign an approved informed consent for this study

Exclusion Criteria:

- Vulnerable study population

- Pregnant or nursing women

- Women planning a pregnancy within the study period

- Current or previous Xolair use

- Biopsy proven neutrophilic rich urticaria

- Known history of adverse reaction to Nucala

- Severe asthma requiring high-dose inhaled or systemic corticosteroids