Sublingual grass allergen tablet immunotherapy provides sustained clinical benefit with progressive immunologic changes over 2 years

Background: This is an interim analysis of a randomized, double-blind, placebo-controlled phase III trial with 3 years of daily treatment with grass tablet immunotherapy (GRAZAX; ALK-Abello A/S, Horsholm, Denmark) or placebo, followed by 2 years of follow-up to assess the persistent efficacy. Objective: We sought to evaluate the efficacy and safety of specific immunotherapy with grass allergen tablets compared with placebo after treatment covering 2 consecutive grass pollen seasons. Methods: The interim analyses included 351 adult participants with moderate-to-severe allergic rhinoconjunctivitis caused by grass pollen. Participants were treated with active (n = 189) or placebo (n = 162) tablets for an average of 22 months. All participants were allowed to use symptomatic rescue medication. Results: The primary efficacy analysis showed highly significant mean reductions of 36% in rhinoconjunctivitis symptom score (P<.0001; median reduction, 44%) and 46% in rhinoconjunctivitis medication score (P<.0001; median reduction, 73%) in the active group relative to the placebo group. Mean rhinoconjunctivitis quality of life was 33% better (P<.0001; median, 40%). Clinical improvements were paralleled by significant changes in allergen-specific immunoglobulins. The treatment was well tolerated, and adverse events led to withdrawal in less than 1% of participants. There were no serious adverse events related to treatment. Conclusion: Grass allergen tablet immunotherapy showed progressive immunologic changes and highly significant efficacy over 2 years of continued treatment.