D2.491 - Efficacy of a 300IR birch liquid sublingual immunotherapy during the alder and hazel pollen seasons: results of the YOBI trial

The “birch homologous group” comprises several tree species including birch, alder, and hazel which show substantial cross-reactivity. Consequently, patients sensitised to birch pollen may experience allergic rhinoconjunctivitis (ARC) symptoms outside the peak birch season, including during the earlier alder and hazel pollen seasons (PSs). A large European, randomised, double-blind, placebo-controlled phase III trial (YOBI) evaluated the efficacy and safety of a 300IR birch pollen liquid sublingual immunotherapy (SLIT-liquid) during birch PS and also assessed its efficacy during the alder and hazel PSs.  

In the YOBI trial, two years of daily pre-/co- seasonal treatment with 300IR birch SLIT-liquid or placebo were assessed in a paediatric ARC population aged 5–17 years with/without controlled asthma. This treatment period encompassed the alder and hazel PSs, defined as per EAACI guidelines. An exploratory analysis assessed efficacy of 300IR SLIT-liquid during alder and hazel seasons, patients scored Daily Symptom Score (DSS_0-18) and Daily Medication Score (DMS_0-20) all through the seasons. The Total Combined Score (TCS_0-38) [TCS_0-38=(DSS_0-18)+(DMS_0-20)] was assessed (ANCOVA) during all trees’ PSs.  

In the subset of patients with known alder/hazel sensitisation (Year 1: 300IR n=108; placebo n=58; Year 2: 300IR n=92; placebo n=52), statistically significant differences between the 300IR SLIT-liquid and placebo groups were observed during the alder and hazel PSs. In Year 1, LS mean difference in TCS was −1.85 (95% CI: −3.35 to −0.35; relative difference: −45.28%; p = 0.004). In Year 2, LS mean difference was −1.66 (95% CI: −3.28 to −0.04; p = 0.016) corresponding to a relative difference of -42.89%. The results during alder and hazel PSs mirrored the positive results observed during the birch PS (Table). 

300IR birch SLIT-liquid demonstrated statistically significant reductions in the TCS_0-38 during both the alder/hazel and birch seasons, suggesting that it may improve ARC symptoms and reduce rescue medication use across the broader tree PS.