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).