Dose-Dependent Immunological Responses after a 6-Month Course of Sublingual House Dust Mite Immunotherapy in Patients with Allergic Rhinitis

Abstract

Background: House dust mite (HDM) immunotherapy has proven efficacy in treating allergic rhinitis (AR) symptoms. This trial evaluated the dose-response relationship of SLITone^ULTRA® HDM mix based on immunological parameters and safety in subjects with moderate-to-severe HDM AR not controlled by symptomatic medication. Materials and Methods: A randomized, parallel-group, open-label, clinical trial compared 50/150/300 standard reactivity unit (SRU) doses of SLITone^ULTRA® HDM mix for 6 months. Subjects had moderate-to-severe HDM AR, positive skin prick and IgE against Dermatophagoides pteronyssinus/Dermatophagoides farinae (DP/DF). The primary end point was change from baseline in the IgE-blocking factor against DP after 6 months. Secondary end points measured changes in the IgE-blocking factor for DP at 3 months and for DF at 3 and 6 months, and in IgG₄ and specific IgE to DP/DF after 3 and 6 months. Tolerability was assessed through the evaluation of all adverse events (AEs). Results: A total of 219 subjects were randomized and 196 completed the trial. Dose effect was significant on DP IgE-BF after 6 months (p = 0.018). The change in the DP IgE-blocking factor at a 300-SRU dose was higher than at other doses after 3 (p = 0.008) and 6 (p = 0005) months of treatment. Similar changes were observed for IgG₄ and allergen-specific IgE. The number of AEs increased with the dose and were mild-to-moderate, with no severe treatment-related AEs reported. The most frequent AEs were oral/tongue pruritus, mouth oedema and abdominal upper pain. Conclusions: Data showed a dose-response for immunological markers and safety with a better immunological response for 300 SRU. The highest dose (300 SRU daily) was considered as the optimal maintenance dose.