Methods: Subjects underwent 6-hour environmental exposure chamber (EEC) challenges at baseline and week 24 (end of treatment) in a randomized, placebo-controlled, double-blind trial (NCT01644617) during which subjects received daily 12 SQ-HDM SLIT-tablet or placebo for 24 weeks. An EEC challenge was conducted approximately 1 year after trial completion as part of the Vienna Challenge Chamber’s annual diagnosis update of allergic subjects. The total nasal symptom score (TNSS) and nasal airflow by active anterior rhinomanometry were assessed from hours 2–6 of EEC challenges. TNSS was the sum of 4 nasal symptom scores (maximum=12).
Results: Thirty six subjects who received 12 SQ-HDM SLIT-tablet and 34 who received placebo were assessed at week 24; 16 subjects from each group were assessed at follow-up. Compared with baseline values, TNSS at week 24 improved 47% and −11% with HDM SLIT-tablet and placebo, respectively, and at one-year follow-up improved 34% and 10%. Nasal airflow decreased 33% at baseline, 21% at week 24, and 22% at follow-up in HDM SLIT-tablet subjects, and 39% at baseline, 30% at week 24, and 30% at follow-up in placebo subjects.
Conclusions: Improvement of allergic rhinitis symptoms were observed up to 1 year after completing 24-weeks of treatment with the 12 SQ-HDM SLIT-tablet.