Eosinophilia During Lenalidomide Therapy in Myelodysplastic Syndrome

Background Lenalidomide is an immunomodulatory therapy used to treat multiple hematologic malignancies. The incidence of eosinophilia and hypereosinophilia during lenalidomide therapy, and the requirement for high-dose steroids are not well-defined Patients and Methods We retrospectively reviewed 44 patients with myelodysplastic syndromes who were treated with lenalidomide therapy from August 2006 and March 2023. Results Eosinophilia (0.5-1.5 × 109/L) and hypereosinophilia (>1.5 × 109/L) were observed in 6 patients (14%) and 4 patients (9%), respectively. The median duration of lenalidomide therapy was 6.5 months. Backward multivariate ordinary logistic regression identified higher absolute eosinophil count (OR, 4759.986; 95% CI, 11.223-2018772.073; P=0.006) and longer duration of lenalidomide therapy (OR, 1.148; 95% CI, 1.012-1.302; P=0.032) as independent prognostic factors for the incidence of eosinophilia and hypereosinophilia. There was a trend for a higher use of high-dose steroids with hypereosinophilia. The median time to develop the first occurrence hypereosinophilia was 0.5 months. Steroids were used in 40% of patients with eosinophilia or hypereosinophilia. All events resolved with discontinuation of lenalidomide and/or use of steroids. No long-tern lasting adverse effects were recorded. Conclusion Lenalidomide may induce or worsen existing eosinophilia which may lead to the need for steroids within a month of therapy. MicroAbstract Lenalidomide therapy may be associated with the development of eosinophilia (23%) or hypereosinophilia (9%) in patients with myelodysplastic syndrome. Among patients with eosinophilia, 40% of patients required systemic steroid during lenalidomide therapy.