Oral Plasma Kallikrein Inhibitor BCX7353 is Safe and Effective as an On‐Demand Treatment of Angioedema Attacks in Hereditary Angioedema (HAE) Patients: Results of the ZENITH‐1 Trial: 110

Abstract

Remedios P erez Calder on, PhD, Nicola Giangrande, MD, Mar ıa Angeles Gonzalo Garijo, PhD, Silvia S anchez Vega, MD, Mariana Marcos Fern andez, MD, and Borja Bartolom e, PhD; Allergy Department, Infanta Cristina University Hospital, Badajoz, Spain, Allergy Department, Zafra-Llerena Hospital, Badajoz, Spain, Primary Health-Care Center, Pueblonuevo del Guadiana, Badajoz, Spain, R+D Department, Roxall Bilbao, Bilbao, Spain. RATIONALE: In Europe, hypersensitivity reactions to ants are exceptional. In 2013 we described the first case of anaphylaxis due to Messor barbarus (MB) ant in a patient with hymenoptera venom allergy and systemic mastocytosis (SM). SDS-PAGE Immunoblotting identified an IgE binding band of 45-55 kDa in the extract of MB’s body which showed partial cross-reactivity with venom protein from Apis, Polistes and especially Vespula. Thus, we decided to investigate the possible sensitization to MB proteins in a sample of patients with Hymenoptera venom hypersensitivity. METHODS: Twenty-two patients were studied. Exhaustive anamnesis of exposition and reaction to ant bites, prick test with MB’s body extract (10 mg/ml), tryptase serumdetermination, andREMA score (SpanishNetwork on Mastocytosis) to predict systemic mastocytosis were carried out. RESULTS: Three women and 19 men, average age of 50 years, were studied. Sixteen presentedwith systemic reactions and 6 local ones. Four of 22 patients referred ant bites but only one experienced symptoms (anaphylaxis). Prick tests with MB’s body extract were positive in 10 patients. Only in 3 patients, subsequently diagnosed of systemic mastocytosis, tryptase serum was positive and REMA score was more than 2 points. CONCLUSIONS: We detected sensitizations to MB ant body in almost half of patients with Hymenoptera venom hypersensitivity. Nevertheless, we do not know its clinical relevance because most of them had not suffered ant bites. But taking into account our previously reported case, we consider that the investigation of sensitization to other kinds of Hymenoptera may be of interest, especially in patients with systemic mastocytosis.