Clinical efficacy of 300IR 5-grass pollen sublingual tablet in a US study: The importance of allergen-specific serum IgE

Background: Previous trials have demonstrated the efficacy, safety, and optimal dosage of the 5-grass pollen sublingual tablet for adults and children with grass pollen-induced allergic rhinoconjunctivitis. Objectives: We sought to evaluate the efficacy and safety of 300 index of reactivity (IR) 5-grass pollen sublingual tablet in US adults. Methods: Adults with grass pollen allergy and Rhinoconjunctivitis Total Symptom Scores of 12 or greater (scale, 0-18) during the previous grass pollen season were randomized in a double-blind, placebo-controlled study to receive 300IR 5-grass pollen sublingual tablet or placebo starting 4 months before and continuing through the pollen season. The primary efficacy end point was the daily Combined Score (CS; scale, 0-3), which integrates symptoms and rescue medication use. Results: Four hundred seventy-three participants were randomized. The mean daily CS over the pollen period was significantly lower in the active treatment group versus the placebo group (least-squares mean difference: -0.13; 95% CI, -0.19 to -0.06; P =.0003; relative reduction: 28.2%; 95% CI, 13.0% to 43.4%). In placebo-treated participants, the daily CS least-squares mean was 0.32 in the subgroup with baseline timothy grass-specific serum IgE of less than 0.1 kU/L (n = 23) and 0.46 in those with baseline timothy grass-specific serum IgE of 0.1 kU/L or greater (n = 204). The most frequent reported adverse events were oral pruritus, throat irritation, and nasopharyngitis. There were no reports of anaphylaxis, and no actively treated participant received epinephrine. Conclusion: In US adults with grass pollen-induced allergic rhinoconjunctivitis, preseasonal and coseasonal treatment with 300IR 5-grass pollen sublingual tablet demonstrated clinically meaningful efficacy, especially in study subjects with measurable timothy grass-specific serum IgE. Use of 300IR 5-grass pollen sublingual tablet was safe and well tolerated. A requirement for a measurable level of allergen-specific serum IgE should be considered in future studies in this field.