Successful non‐myeloablative allogeneic transplantation for treatment of idiopathic hypereosinophilic syndrome

In this report, we describe two patients with idiopathic hypereosinophilic syndrome (HES) who received a non‐myeloablative allogeneic transplantation following a reduced‐intensity preparative regimen of melphalan and fludarabine. In both cases, complete donor chimaerism and remission were achieved, and have lasted for more than 10 months. This report provides proof of principle for the feasibility of non‐myeloablative transplantation for patients with idiopathic HES, who can show co‐morbidity due to eosinophilic infiltration of their organs.