A randomized, double‐blind, placebo‐controlled trial with mannan‐conjugated birch pollen allergoids

Abstract

AbstractBackgroundThere is still great need to develop new strategies to improve the efficacy of allergen immunotherapies with optimal safety standards for patients. A new promising approach is to couple allergoids to mannan. The objective of this phase IIa/IIb study was to identify the optimal dose of mannan‐conjugated birch pollen allergoids for the short‐course treatment of birch pollen–induced allergic rhinoconjunctivitis.MethodsFor this prospective, randomized, double‐blind, placebo‐controlled, dose‐finding study, 246 birch pollen–allergic adults received 0.5 mL placebo or 1000, 3000 or 10,000 mTU/mL of mannan‐conjugated birch pollen allergoids at five pre‐seasonal visits. Efficacy was assessed by comparing allergic rhinoconjunctivitis symptoms and use of anti‐allergic medication during the peak of the birch pollen season 2020. Immunologic, tolerability and safety effects were also analysed.ResultsThe highest dose of mannan‐conjugated birch pollen allergoids reduced the combined symptom and medication score during the peak birch pollen season by a median of 24.7% compared to placebo. The production of Bet v 1 specific IgG4 significantly increased in a dose‐dependent manner (3.6‐ and 4.5‐fold) in the 3000 and 10,000 mTU/mL groups. The Bet v 1 specific IgE/IgG4 ratio was also strongly reduced (up to −70%). No fatalities nor serious adverse events were reported, and no adrenaline was used. In total, four systemic reactions occurred (two grade I and two grade II).ConclusionAll doses of mannan‐conjugated birch pollen allergoids can be considered as safe. Since the application of 10,000 mTU/mL resulted in the highest efficacy, this dose qualifies for further investigation.