Long-term effects of a house dust mite sublingual immunotherapy tablet in an environmental exposure chamber trial

Abstract Background Treatment with SQ house dust mite (HDM) sublingual immunotherapy (SLIT) tablet is effective for HDM respiratory allergic disease, but data on long-term effects are lacking. Objective Post hoc analyses were conducted to determine the long-term effect of SQ HDM SLIT-tablet on nasal, ocular, and cough symptoms 1 year after discontinuation of treatment. Methods Study participants underwent environmental exposure chamber (EEC) challenges at baseline and week 24 in a randomized, placebo-controlled, double-blind trial (NCT01644617) during which participants received daily 12 SQ-HDM, 6 SQ-HDM, or placebo for 24 weeks. Asthma had to be stable, well controlled, and nonsevere. The mean total asthma symptom score (TASS; sum of 3 symptoms: cough, wheeze, and dyspnea) during baseline and week 24 EEC challenge was analyzed in all participants who completed the trial (n = 106). Approximately 1 year after trial completion, another EEC challenge was conducted in a subset of participants (n = 51). Total nasal symptom score (sum of 4 symptoms), total ocular symptom score (sum of 2 symptoms), and cough were assessed. Results Compared with baseline and end-of-treatment values, sustained improvement of all symptoms assessed at the 1-year follow-up EEC challenge was evident in participants treated with 12 SQ-HDM. Results with 6 SQ-HDM were less notable. After 24 weeks of 12 SQ-HDM, TASS during EEC challenge was improved 65% vs baseline; at 1-year follow-up, cough was improved 57% vs baseline. Conclusion Persistent improvement of nasal and ocular symptoms was observed up to 1 year after completing 24 weeks of 12 SQ-HDM treatment. Beneficial effects on cough were also observed. Trial Registration clinicaltrials.gov Identifier NCT01644617.