157 The Post-Treatment Efficacy of House Dust Mite Sublingual Allergen Immunotherapy Tablets in Adults With Allergic Rhinitis

BACKGROUND: The efficacy and safety of 2 doses of sublingual allergen immunotherapy house dust mite (HDM) tablets administered for 12 months were demonstrated in a randomized, double-blind, placebo-controlled study of adults suffering from HDM-related allergic rhinitis. Here we report the efficacy during the 12-month, treatment-free, follow-up period. METHODS: Of the 509 patients randomized, 412 were included in the year 2 full analysis set (500 IR = 132, 300 IR = 134, Placebo = 146). The primary efficacy variable was the Average Adjusted Symptom Score (AAdSS, scale 0–12) an average of the daily score based on the severity of 4 rhinitis symptoms (sneezing, rhinorrhea, nasal pruritus and nasal congestion) and adjusted for rescue medication usage. The AAdSS was analyzed, at the end of the post-treatment period, using an ANCOVA and at 3, 6, 8 and 12 months after treatment cessation in a secondary analysis, using repeated measures ANCOVA. RESULTS: At the end of the post-treatment period, the 500 IR group showed a significant improvement in AAdSS vs. placebo (P = 0.021) with a LS Means difference of –0.70 (95% CI [–1.29, –0.11]), corresponding to –19.1%. The LS Means difference of –0.62 (95% CI [–1.20, –0.05]) between the 300 IR and placebo groups was also significant (P = 0.034), corresponding to –17.0%. The difference between the active treatment groups was not statistically significant. Eight months after treatment cessation, which corresponds to the autumn peak in HDM, the relative LS mean difference was –20.9% (P = 0.0079) for the 500 IR and was –25.5% (P = 0.0011) for the 300 IR group. CONCLUSIONS: During the 12-month post-treatment period, house dust mite sublingual immunotherapy tablets at doses of 500 IR and 300 IR provided sustained symptom relief, demonstrating their efficacy after treatment cessation.