BACKGROUND: Allergic rhinitis and/or conjunctivitis (AR/C) induced by tree pollen is common and negatively impacts quality of life in children and adolescents. This phase III trial investigated the efficacy and safety of the SQ tree SLIT-tablet in a paediatric population (5-17 years) with moderate-to-severe AR/C induced by pollen from birch and trees in the birch homologous group. METHODS: Nine hundred and fifty-two subjects were randomized (1:1) to daily treatment with SQ tree SLIT-tablet or placebo for up to 52 weeks and had free access to AR/C symptom-relieving medications. The primary endpoint was the average total combined score (TCS)
sum of average daily symptom score (DSS) and average daily medication score (DMS) during the birch pollen season (BPS). Key secondary endpoints included average DSS and DMS during BPS and average TCS, DSS and DMS during tree pollen season (TPS). RESULTS: SQ tree SLIT-tablet demonstrated a statistically significant and clinically relevant treatment effect compared with placebo for the TCS during BPS with an absolute treatment difference of 1.29 (95% CI: 0.58, 2.00
p = .0004) and a relative reduction of 21.9% (95% CI: 10.6, 31.9). Results were substantiated by reductions in both DSS and DMS versus placebo during the BPS and in DSS, DMS and TCS during the TPS. Treatment was generally well tolerated. Most treatment-related adverse events were mild or moderate local administration site reactions. CONCLUSION: This is the first paediatric trial to provide robust evidence of efficacy and safety of the SQ tree SLIT-tablet in tree pollen-induced AR/C in a paediatric population (5-17 years).