Allergic rhinitis activity and efficacy of 300 <scp>IR</scp> house dust mite sublingual immunotherapy tablet in pediatrics

BACKGROUND: House dust mite (HDM) allergic rhinitis (HDM-AR) fluctuates over time with exposure conditions, making disease activity assessment essential when demonstrating treatment efficacy. We conducted post hoc tertile analyses to more accurately assess the efficacy of 300 IR HDM sublingual immunotherapy (SLIT) tablet in moderate-to-severe HDM-AR pediatric patients during periods of increased disease activity. METHODS: Data from two Japanese randomized controlled trials of 300 IR HDM SLIT-tablet were used to assess the average adjusted symptom score (AASS) and average combined symptom and medication score (ACSMS). To determine the impact of HDM-AR activity, placebo group scores during the primary period (end of treatment) at each center were ranked from lowest to highest to establish three tertiles. Scores differences between SLIT and placebo were analyzed in each tertile using ANCOVA. RESULTS: The first analysis included patients aged 5-16 years (300 IR = 193, placebo = 210). During the primary period, the effect of the SLIT-tablet, estimated at -13.1% (AASS) and -12.9% (ACSMS) versus placebo overall, was more pronounced in the highest tertile (relative differences -27.3% and -28.5%, respectively), with similar results across age groups. The second analysis including a pool of adolescents (300 IR = 120, placebo = 135) showed an overall effect of -19.9% (AASS) and -21.2% (ACSMS) with 300 IR versus placebo, with again greater improvements in the highest tertile (-32.5% and -34.1%, respectively). CONCLUSION: The greatest improvements occurred in the tertile where pediatric patients exhibited higher disease activity. This underscores the true efficacy of 300 IR HDM SLIT-tablet during periods when patients experience the most troublesome symptoms.