Long-term treatment of Japanese cedar pollinosis with Japanese cedar pollen SLIT drops and persistence of treatment effect: A post-marketing clinical trial

Abstract Background There have been no reports of treatment effect persistence after long-term sublingual immunotherapy (SLIT) in patients with Japanese cedar (JC) pollinosis. Therefore, we conducted a post-marketing clinical trial to investigate the efficacy, safety, and effect persistence of JC pollen SLIT drops after approximately 3 years of treatment. Methods This was an open-label trial of 233 patients with JC pollinosis who were treated with JC pollen SLIT drops for approximately 3 years (2015–2017) and followed-up for an additional 2 years (2018–2019). Efficacy and effect persistence were evaluated using nasal and ocular symptom scores, daily use of rescue medication, and Japanese Rhinoconjunctivitis Quality of Life Questionnaire scores recorded during the JC pollen dispersal season of each year. Safety was evaluated by monitoring adverse events and adverse drug reactions. Results The mean combined total nasal symptom and medication score (range 0–18) during the peak symptom periods of 2015 through 2019 were 5.47 ± 3.38, 4.52 ± 3.13, 3.58 ± 2.63, 5.28 ± 4.01, and 6.83 ± 4.65, respectively. The percentage of patients who used no rescue medications during the same periods was 64.8%, 75.2%, 80.3%, 63.7%, and 50.3%, respectively. A total of 138 adverse drug reaction incidents were recorded in 73 of the 233 patients (31.3%), of which 134 incidents (97.1%) were mild in severity. Conclusions JC pollen SLIT drops demonstrated treatment duration-dependent efficacy with effects that persisted for 2 years after cessation of treatment. The drug had a favorable safety profile over the 5-year study period.