Effectiveness of benralizumab in the Tokyo Asthma Study (TOAST): A real-world prospective interventional trial

Background: Biologics are integral in the management of severe asthma. As the effectiveness of the anti-IL-5 receptor antibody benralizumab in Japan remains elusive, this study aimed to assess its real-world effectiveness in Japanese patients with severe asthma.

Methods: This prospective, interventional, single-arm clinical trial was conducted across ten facilities in Japan between September 2020 and July 2022. Adult patients with severe eosinophilic asthma (peripheral blood eosinophil count ≥150 cells/μl) were enrolled and treated with benralizumab. The primary endpoint was the change in ACQ-5 score from baseline to week 24.

Results: Of 103 patients, 98 (mean age: 62.1 years, women: 55.1 %, regular oral corticosteroids [OCS] treatment: 20.4 %) were included in the analysis. From baseline to week 24, benralizumab significantly improved ACQ-5 (-0.67, 95 % CI: -0.94 to -0.39) and AQLQ (0.71, 95 % CI: 0.46 to 0.96) scores with an increase in FEV1 (87 ml, 95 % CI: 15-159 ml). The maintenance OCS dose and the percentage of OCS users decreased from 13.9 mg/day to 6.0 mg/day and from 20.4 % to 9.2 %, respectively. Multivariable analysis identified baseline blood eosinophil count (≥400 cells/μl) and fractional exhaled nitric oxide (≥22 ppb) as independent predictors of therapeutic response to benralizumab. Benralizumab treatment was discontinued due to nonserious adverse events and patient choice in four and three patients, respectively.

Conclusions: In a real-world setting in Japan, patients with severe eosinophilic asthma treated with benralizumab demonstrated substantial improvements in asthma control, quality of life, and respiratory function with reduced OCS usage.

Trial registration: Japan Registry of Clinical Trials (jRCTs031190237).