CD-sens and component-resolved diagnostics to hazelnut, used separately or in combination, may improve the diagnostic accuracy and safety and reduce overdiagnosis of hazelnut allergy.

Background: Peanut oral immunotherapy (pOIT) has showed good short-term outcomes, but allergic reactions may prevent effective up-dosing and is a major cause of stopping OIT. In placebo-controlled trials, omalizumab has been shown to facilitate allergen immunotherapy and increase tolerance to peanut.Objective: We hypothesized that by combining omalizumab with pOIT, and monitor treatment effects with basophil allergen threshold sensitivity tests (CD-sens), peanut allergic patients could safely initiate pOIT and thereafter slowly withdraw omalizumab.Methods: This is the 2nd part of a one-armed open phase-2 study where peanut allergic adolescents (n = 23) started pOIT after an individualized omalizumab treatment. The pOIT dose was increased from 280 to 2800 mg peanut protein in 8 weeks followed by an individualized step-wise withdrawal of omalizumab, based on clinical symptoms and CD-sens levels. pOIT continued for 12 weeks followed by an open peanut challenge. Peanut CD-sens and allergen-binding activity (ABA) and IgE-ab, IgG-ab and IgG4-ab to peanut and its components were measured during the study.Results: All 23 patients successfully reached the 2800 mg maintenance dose. Moderate/ systemic allergic reactions were rare while receiving full-dose omalizumab. Eleven of 23 (48%) successfully continued with pOIT after omalizumab was stopped. Compared to treatment failures, median baseline IgE-ab to peanut components Ara h 1-3 and CDsens to peanut were significantly lower among successfully treated patients and IgG4ab to peanut, Ara h 2 and 6 increased significantly more during treatment. Conclusions and clinical relevance:This study indicates that omalizumab is an effective adjunctive therapy for initiation and rapid up-dosing of pOIT; however, adverse events from pOIT become more frequent as omalizumab doses are decreased.Clinical trials registration: ClinicalTrials.gov; NCT02402231. EudraCT; 2012-005625-78. K E Y W O R D Sanaphylaxis, basophil, food allergy, omalizumab, oral immunotherapy, paediatrics | 1329 BRANDSTRÖM eT Al.