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 500IR and was -25.5% (p=0.0011) for the 300IR 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.