Treatment duration-dependent efficacy of Japanese cedar pollen sublingual immunotherapy: Evaluation of a phase II/III trial over three pollen dispersal seasons

Abstract

Background: We conducted a randomized, placebo-controlled, double-blind clinical trial to investigate the optimal dose and long-term efficacy and safety of Japanese cedar (JC) pollen tablets for SLIT (JapicCTI-142579). Here, we report details of the effects of the JC pollen SLIT tablet on rhinitis and conjunctivitis symptoms over three pollen dispersal seasons. Methods: A total of 1042 JC pollinosis patients (aged 5–64 years) were randomized to receive tablets containing placebo (P), 2000, 5000, or 10,000 Japanese allergy units (JAU) of JC pollen for 15 months to identify an optimal dose. Patients receiving P (n = 240) and the optimal dose (5000 JAU; A, n = 236) were then randomized to receive P or A for an additional 18 months (AA, AP, PA, and PP groups, allocation ratio 2:1:1:2). Nasal and ocular symptoms, rescue medication use, and quality of life (QOL) were assessed on quantitative scales. Results: In the second and third seasons, the AA, AP, and PA groups exhibited significantly better improvements in nasal, ocular, and medication scores compared with the PP group in the order AA > AP > PA > PP during the second season and AA > PA > AP > PP during the third season. Rescue medication use and QOL scores were also significantly better in the AA, AP, and PA groups compared with the PP group. Conclusions: The JC pollen SLIT tablet relieved nasal and ocular symptoms and medication use and improved QOL in a treatment duration-dependent manner. Continuous dosing regimens appear to enhance the efficacy of the drug. Keywords: Allergic rhinitis, Allergen immunotherapy, Japanese cedar pollen, Placebo-controlled, Sublingual immunotherapy tablet