Efficacy and safety of low-dose imatinib in an elderly patient with mixed phenotype acute leukemia with t(9;22)(q34;q11.2);BCR-ABL1

Optimal treatment for Philadelphia chromosome-positive mixed phenotype acute leukemia (Ph+ MPAL), particularly in elderly patients with comorbidities, has not been established. We present the elderly Ph+ MPAL case who discontinued initial treatment with dasatinib and whose disease was successfully controlled by low-dose imatinib with monitoring of drug concentrations in blood.