An analysis of factors related to the effect of sublingual immunotherapy on Japanese cedar pollen induced allergic rhinitis

Background: Sublingual immunotherapy (SLIT) can improve the symptoms of allergic rhinitis and modify its natural history; however, its efficacy varies among patients. This study aimed to determine which factors modify the effect of SLIT through post hoc analysis of a previous phase 3 trial of standardized Japanese cedar (JC) pollen extract (CEDARTOLEN®). Methods: The study included 482 patients who had previously completed a phase 3 trial during two seasons. The SLIT and placebo groups each contained 241 subjects. Because pollen dispersal differed in the two seasons, we identified good and poor responders from the SLIT group in the 2nd season. We compared patient baseline characteristics, changes in serum immunoglobulin, and severity of symptoms in the 1st season between good and poor responders, as well as between SLIT and placebo groups. Results: When we compared the baseline characteristics of good and poor responders, a significant difference was observed in body mass index (BMI) such that the patients with BMI ≥25 presented with lower treatment efficacy. No significant difference was observed in correlation with any other factors or treatment-induced alterations of serum immunoglobulin levels. We found that 75.3% of the patients with moderate symptoms and 50.9% of the patients with severe or very severe symptoms in the 1st season met our criteria for good responders in the 2nd season. Conclusions: BMI might modify the effect of SLIT; however, other factors were not related clearly. The severity of symptoms in the 1st season of treatment does not predict that in the 2nd season. Keywords: Allergic rhinitis, Japanese cedar pollen, Phase 3 trial, Post hoc analysis, Sublingual immunotherapy