Oligospermia in a Patient Receiving Imatinib Therapy for the Hypereosinophilic Syndrome

To the Editor: We report the development of oligospermia in a young man treated with imatinib for the hypereosinophilic syndrome. Imatinib was developed as a selective inhibitor of the BCR-ABL tyrosine kinase that is constitutively activated in chronic myeloid leukemia (CML). It also potently inhibits other normal cellular tyrosine kinases, c-abl, c-arg, and the receptors for platelet-derived growth factor (PDGF) and stem-cell factor (c-kit). Imatinib has been successfully used therapeutically against these kinases in other malignant diseases, including the hypereosinophilic syndrome.1 The role of these tyrosine kinases in normal cellular function is still being elucidated, and their inhibition by imatinib . . .