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.

The 75-year-old male patient had been diagnosed with CML 25 years ago. Over 3 years after starting bosutinib, he was diagnosed with a HGBCL. A total of six courses of DA-EPOCH-R therapy brought complete remission of the lymphoma. Eight months after stopping bosutinib, BCR-ABL1 transcript copies remained undetectable by RT-PCR.