Suplatast tosilate reduces peripheral blood eosinophil levels in patients with eosinophilia: a real-world retrospective study

Introduction Eosinophilia is a rare disease characterized by an increase in eosinophils. Suplatast tosilate is a selective Th2 cytokine inhibitor that can reduce eosinophils. There is currently a lack of clinical studies of suplatast tosilate in the treatment of eosinophilia. Research objective To explore whether suplatast tosilate can reduce blood eosinophil levels in eosinophilia and the factors that might influence the improvement. Methods A real-world retrospective study of 20 patients with eosinophilia was conducted using electronic medical record information. The main outcome measure was the difference in peripheral blood absolute eosinophil count (AEC) and percentage (EOS%) before suplatast tosilate (baseline) and the lowest AEC during the 1-year period of suplatast tosilate treatment (post-treatment). Data on age, gender, disease duration, involved organs, and concomitant medication were collected, and subgroup analysis and linear regression analysiswere performed. Results Subjects were predominantly male, with a mean age of 33 years and a disease duration of approximately 30 months. After treatment with suplatast tosilate, the patient's AEC (p=0.029) and EOS% (p=0.016) significantly decreased. The decline in eosinophils was more pronounced in patients who were male, age < 33 years, disease duration < 30 months and gastrointestinal system involvement. In addition, the shorter the course of the disease, the greater the relative decrease in eosinophils after suplatast tosilate treatment (β=-0.018, p<0.001). Conclusions Suplatast tosilate is effective in reducing peripheral blood eosinophil levels in patients with eosinophilia. Large-scale prospective cohort studies are needed for further confirmation.