[Treatment with a tyrosine-kinase inhibitor of for c-KIT mutation and AML1-ETO double positive refractory acute myeloid leukemia].

Translocation (8;21)/AML1-ETO is considered a favorable cytogenetic abnormality in acute myeloid leukemia (AML). However, the outcomes associated with KIT mutations in AML1-ETO have not been elucidated. A 16-year-old boy was diagnosed with recurrent AML. Although he underwent hematopoietic stem cell transplantation (HSCT) twice, the leukemia relapsed and grew resistant to several chemotherapies. We began to treat him with imatinib, but stopped on the 31st day as it did not show any effects. Later, we administered dasatinib. However, we discontinued this because he showed severe nasal hemorrhage 87 days after administration of dasatinib. The therapeutic benefit of tyrosine-kinase inhibitor (TKI) was estimated by quantitative analysis of AML1-ETO and the patient's clinical impression. We did not conduct analyses to determine the effective concentration of TKI. The patient has not yet shown any major molecular response. Therefore, we conclude that TKI may be useful for slight palliation of symptoms in KIT-positive AML. However, patients with refractory AML associated KIT mutations in AML1-ETO should not be considered for TKI monotherapy.