Persistence of the clinical effect of grass allergen peptide immunotherapy after the second and third grass pollen season

Abstract Background Grass allergen peptides are in development for the treatment of grass pollen-induced allergic rhinoconjunctivitis(ARC). A previous randomized, placebo-controlled study demonstrated grass allergen peptides significantly improved total rhinoconjunctivitis symptom scores(TRSS) following post-treatment challenges(PTC) to rye grass in an Environmental Exposure Unit(EEU) after one intervening grass pollen season(GPS1). Objective To evaluate the efficacy/safety of four dosing regimens of grass allergen peptides after a second(GPS2) and third(GPS3) intervening grass pollen season in the EEU. Methods Eligible individuals who were randomized in the parent study(GPS1) during the first year of recruitment were invited to participate in GPS2 and GPS3, which took place 1 and 2 years after treatment cessation respectively. Participants were not treated further and both participants and study personnel remained blinded. The primary efficacy endpoint was the change in mean TRSS(reported every 30 minutes) from GPS1 baseline to the follow-up PTC, calculated across all time points over days 2-4 for GPS2, and across hours 1-3 over days 2-4 for GPS3. Secondary efficacy endpoints and safety were also assessed. Results 122 and 85 participants were enrolled in GPS2 and GPS3 respectively. A greater improvement from baseline in mean TRSS at PTC was observed in the 8x6nmolQ2W group compared to placebo in GPS2(-6.0 vs. -3.6, P=.0535) and GPS3(-6.2 vs. -3.6, P=.1128). Similar findings were observed for the 4x12nmolQ2W group at GPS3(-6.4 vs. -3.6, P=.0759). No adverse safety signals were detected. Conclusion Treatment with grass allergen peptides led to an improvement in ARC symptoms after three intervening grass pollen seasons, corresponding to up to 2 years off treatment.