Evaluation of the Efficacy of Allergen-specific Immunotherapy Using Assessment in an Allergen Exposure chamber-a Randomized Placebo-controlled Double-blind Study

The main objective of the study is to measure and correlate clinical parameters suitable for the assessment of allergen immunotherapy (AIT) with an aluminum hydroxide-adsorbed preparation of house dust mite (Dermatophagoides pteronyssinus/ Dermatophagoides farinae) allergens in adults with moderate to severe allergic rhinitis/rhinoconjunctivitis with or without controlled allergic bronchial asthma caused by house dust mite (HDM) allergens. The assessment of clinical responses will be evaluated following an allergen challenge in allergen exposure chamber (AEC) before and during the course of AIT. Patients' response to therapy will be evaluated as well as in the AEC and by patient's personal environment (Diary).

This clinical trial will be performed as a randomized, double-blind, placebo-controlled phase IV study in adult patients. Thus, 2 parallel groups, one active treated and one placebo group, will be investigated. Patients from 18 to 65 years of age with moderate to severe allergic rhinitis or rhinoconjunctivitis to HDM allergens, with or without controlled allergic bronchial asthma, will be enrolled. The efficacy will be evaluated using an AEC (TNSS) and additionally in the patient's natural environment (SMS). The screening phase will begin approximately in May and last until September 2024. All patients fulfilling the eligibility criteria at Screening Visit 1 (S1) will perform an AEC visit (AEC-pre) in October, followed by an e-Diary phase in November, December (Diary-pre). For the assessment of the pre-treatment score 4 consecutive weeks will be recorded and at least 2 consecutive weeks with complete daily entries must available. Adequate symptoms are defined as patient randomization criteria in the respective section of the synopsis/protocol. After randomization, patients will be treated for approximately 10 months. Afterwards a second Diary phase (Diary-post) will be performed. For the assessment of the post-treatment score, at least 2 consecutive weeks with complete daily entries must be available. Then, a second, posttreatment challenge (AEC-post) will follow. Last patient last visit is planned for January 2026. For the trial approximately 80 male and female outpatients (18 to 65 years of age) will be screened, and 67 patients will be randomized 1:1 verum/placebo. It is assumed, that this number of patients will yield a total of at least 60 patients with available post-treatment assessments, assuming a dropout rate of 10%. Additionally, data from 11 healthy subjects from a previous study with an identical setting will be included in the correlation analysis. There will be no replacement strategy employed for patients dropping out prematurely.