Safety Of A Sublingual Tablet of House Dust Mite Allergen Extracts In An Environmental Exposure Chamber Study

Rationale: The efficacy of house dust mite (HDM) sublingual tablets was demonstrated in an environmental exposure chamber (EEC) study of patients with allergic rhinitis upon exposure to HDM allergens. Here we report the safety results.
Methods: Adults (18–55 years) with medically confirmed HDM-associated allergic rhinitis were randomized in this DBPC study to receive 500IR, 300IR or 100IR HDM tablet or placebo daily for 6 months. Patients with intermittent asthma were eligible. Participants were exposed to five 4-hour allergen challenges in the EEC (baseline, treatment months 1, 2, 4, 6). Adverse events (AE) were monitored throughout the study and analyzed descriptively. All patients receiving at least one dose of the investigational product were included in the safety set.
Results: 355 patients (safety set: 500IR=93, 300IR=86, 100IR=89 and Placebo=87) were randomized. 94% (500IR), 91% (300IR), 97% (100IR) and 83% (Placebo) reported at least one AE on treatment. Application site reactions were the most commonly reported AEs (500IR=74%, 300IR=70%, 100IR=69%, and Placebo=37%). The incidence of asthma and related symptoms was higher during the peri-EEC challenge periods (i.e., the day of and the day after challenge; range: 37%-45%) than outside these periods (16%-21%) but was similar across treatment groups. No anaphylaxis or serious drug-related AEs were reported. 20 patients withdrew due to a TEAE, mostly due to application site reactions.
Conclusions: Treatment with HDM sublingual tablets was generally well tolerated regardless of dose. While asthma and related symptoms were more common during the peri-EEC challenge periods, rates did not differ between active and placebo treatment.