Intestinal bleeding in patients with chronic myelogenous leukemia treated with tyrosine kinase inhibitors

Tyrosine kinase inhibitors (TKIs) are highly effective in the treatment of chronic myelogenous leukemia (CML), but there have been a few adverse event reports describing gastrointestinal bleeding. We clinically analyzed two patients who developed intestinal bleeding during the administration of TKIs for CML. Platelet counts of both patients were normal. The patients showed endoscopic findings characterized by mildly hemorrhagic mucosa. The imatinib patient was diagnosed by capsule endoscopy of the small intestine, and required frequent blood transfusions. The dasatinib patient showed occult bleeding due to CD8-positive colitis. We should adequately recognize that gastrointestinal bleeding may occur during the administration of TKIs.