Disease-Modifying Effect of Japanese Cedar Pollen Sublingual Immunotherapy Tablets.

Background: Japanese cedar (JC) pollinosis is a common allergic rhinitis in Japan. JC pollen sublingual immunotherapy (SLIT) tablets are licensed for the treatment of JC pollinosis.

Objective: To assess the disease-modifying effects of JC pollen SLIT tablets over 5 years (2014-2019), comprising a 3-year treatment period and 2-year follow-up.

Methods: A total of 1042 patients with JC pollinosis (aged 5-64 years) were included in the study. An optimal dose-finding study was performed in the first 15 months, after which 240 patients in the placebo (P) group and 236 patients in the optimal active dose (A) group (5000 Japanese allergy units) were re-randomized to receive P or A for an additional 18 months (designated AA, AP, PA, and PP groups). Clinical efficacy was evaluated by the total nasal symptom and medication score (TNSMS) during the peak symptom period of each JC pollen season over 3 years of treatment and 2 years of observation after treatment cessation.

Results: The AA, AP, and PA groups exhibited significantly reduced TNSMS; however, the largest relative reduction was seen in the AA group both during the treatment period (third season, 46.3% vs PP, P < .001) and during the 2-year follow-up period (fourth and fifth seasons, 45.3% and 34.0% vs PP, respectively; P < .001). The most common adverse drug reactions were mild reactions at the administration site.

Conclusions: JC pollen SLIT tablets show sustained clinical efficacy during 3 years of treatment and sustained disease-modifying effects for at least 2 years after treatment cessation.