D2.490 - Consistent efficacy of a seasonal 300IR birch pollen sublingual immunotherapy in children and adolescents during worst pollen exposure: results of the YOBI trial

Birch pollen is the dominant tree pollen allergen in Northern and Central Europe and is a major cause of seasonal symptoms in these areas. During the worst pollen season, highest airborne birch pollen levels induce the greatest allergic rhinoconjunctivitis (ARC) symptom severity. In a large randomised, double-blind, placebo-controlled phase III trial conducted in Europe (YOBI) in paediatric population (5-17 years) to evaluate the efficacy of daily pre-/co-seasonal treatment with 300 IR birch pollen liquid sublingual immunotherapy (SLIT-liquid) over two consecutive birch pollen seasons (BPSs), efficacy was also evaluated during the worst BPSs.

Daily birch pollen counts were collected from national monitoring stations, and the worst BPSs were identified according to EAACI criteria (≥3 consecutive days with ≥100 grains/m³). Efficacy of 300IR birch SLIT-liquid during the worst BPS was measured using the average ARC total combined score (TCS_0-38), the Daily Symptom Score (DSS_0-18), the Daily Medication Score (DMS_0-20), and the Combined Symptom and Medication Score (CSMS_0-6). 

In the intention-to-treat set (active n=369; placebo n=184), the 300IR group showed statistically significant and clinically relevant improvement of the symptom and medication scores compared to placebo over the entire BPS1 and BPS2 (Table). During worst BPSs, difference was higher (Table): In worst BPS1, the least square (LS) mean difference in TCS_0-38 was -2.43 (95% CI: -3.52; -1.34; relative difference: -40.43%; p <0.0001) with consistent improvements in CSMS_0-6, DSS_0-18 and DMS_0-20. During worst BPS2, the TCS_0-38 difference in LS mean was -3.64 (95% CI: -4.89; -2.39, p <0.0001), representing a -49.38% relative difference. Consistent improvements were observed for CSMS_0-6, DSS_0-18 and DMS_0-20 (p<0.0001). 

300IR birch SLIT-liquid demonstrated consistent and robust clinical efficacy in paediatric patients with birch-induced ARC during 2 consecutive BPSs, in particular during the worst BPS periods.