Efficacy and Safety of the SQ-House Dust Mite Sublingual Immunotherapy Tablet in North American Children and Adults: Findings from a Large Randomized, Placebo-Controlled Clinical Trial

Rationale: SQ^®–house dust mite (HDM) sublingual immunotherapy tablet (SLIT-tablet; MK-8237; Merck/ALK) has been demonstrated to have beneficial effects on allergic rhinitis and asthma outcomes, but previous trials were conducted in European subjects. This is the largest trial to assess the efficacy/safety of HDM SLIT-tablets in North American subjects with HDM allergic rhinitis with/without conjunctivitis (AR/C).

Methods: In this double-blinded, multicenter trial (NCT01700192), 1,482 subjects (aged ≥12 years) with HDM AR/C with or without asthma were randomized to daily 12 SQ-HDM SLIT-tablet or placebo for up to 52 weeks. Subjects had a rhinitis daily-symptom score (DSS, 4 nasal symptoms, maximum=12) of ≥6, or ≥5 with 1 severe symptom, on 5 of 7 consecutive days before randomization. The primary endpoint was average total combined rhinitis score (TCRS), defined as rhinitis DSS plus rhinitis daily-medication score (DMS), during the last 8 weeks of treatment.

Results: Treatment with 12 SQ-HDM SLIT-tablet improved TCRS 17% vs placebo (95% CI: −25%, −10%). Improvements vs placebo in the secondary endpoints average rhinitis DSS, rhinitis DMS, total combined rhinoconjunctivitis score, and ARC symptoms assessed by visual analogue scale were 16%, 18%, 17%, and 16%, respectively. All nominal P-values were <0.001 vs placebo except rhinitis DMS. No treatment-related AEs meeting the ICH definition of serious were reported; 1 treatment-related systemic allergic reaction occurred (assessed as moderate) at first administration under medical supervision and was treated with epinephrine.

Conclusions: 12 SQ-HDM SLIT-tablet was well-tolerated and improved HDM ARC symptoms in adults and children. This was the first successful North American trial of a HDM SLIT-tablet.