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: Allergen immunotherapy; Allergic rhinitis; Japanese cedar pollen; Placebo-controlled; Sublingual immunotherapy tablet.