Early onset of action of a 5-grass-pollen 300-IR sublingual immunotherapy tablet evaluated in an allergen challenge chamber

Background: The efficacy and safety of a 5-grass-pollen sublingual immunotherapy (SLIT) tablet (Stallergenes SA, Antony, France) have been evaluated in clinical studies during the pollen season. The allergen challenge chamber (ACC) has been developed as a pharmacodynamic assessment tool to control the environmental allergens and to avoid all problems associated with unpredictable pollen seasons. Objective: We sought to evaluate the onset of action and efficacy of 300-IR (index of reactivity) SLIT tablets by using an ACC. Methods: Patients with grass pollen-induced rhinoconjunctivitis were randomized into the active or placebo groups. A standardized allergen challenge with grass pollen and symptom evaluation every 15 minutes was performed at baseline, 1 week, and 1, 2, and 4 months of treatment. The primary end point was the average rhinoconjunctivitis total symptom score (ARTSS). Allergen-specific basophil activation, T-cell proliferation, and plasmatic IgE and IgG responses were assessed before and after treatment. Results: In the intention-to-treat population (n = 89) a significant treatment effect was achieved after the first month (P = .0042) and second month (P = .0203) and was maintained through to the fourth month (P = .0007). In the active group the ARTSS (means +/- SDs) decreased at each challenge: week 1, 7.40 +/- 2.682; month 1, 5.89 +/- 2.431; month 2, 5.09 +/- 2.088; and month 4, 4.85 +/- 1.999. An improvement (vs placebo) of 29.3% for the mean ARTSS ( median, 33.3%) was observed at end point. Furthermore, the induction of grass pollen allergen specific IgGs was associated with clinical response. The most frequent adverse reactions were local: oral pruritus, ear pruritus, and throat irritation. Conclusions: In this ACC study the 300-IR 5-grass-pollen SLIT tablets had a significant effect on rhinoconjunctivitis symptoms (vs placebo) from the first month of treatment onward. (J Allergy Clin Immunol 2009;124:471-7.)