Study participants
This phase 2 prospective, single-center, open-label study was performed
from March 2018 to February 2021 at the dermatology and allergology
department of the University Medical Center, Utrecht in the Netherlands.
Patients aged 18 years and older suffering from AE attacks with at least
two attacks per month during the last six months despite treatment with
four times the standard daily dose of antihistamines, and no known cause
for AE were eligible for inclusion. Patients were excluded in cases of
accompanying wheals; pregnancy or breastfeeding; a history of rabbit
allergy; ACE-inhibitor use in the past six months; recent or current use
of methotrexate, azathioprine, mycophenolic acid, omalizumab or
cyclosporine. Patients with clinically relevant conditions that had the
potential to compromise the safety of the patient such as renal or
hepatic insufficiency or malignancies or when another diagnosis was
deemed more likely (e.g. allergic AE, drug-hypersensitivity,
mastocytosis or HAE) were also excluded. Patients were allowed to use
rescue medication during acute AE attacks including antihistamines, oral
steroids and intramuscular adrenaline.
All patients provided written informed consent, and the study was
approved by the local ethics committee (protocol number 17-139).