A 35-year-old male was diagnosed with
chronic myeloid leukemia in the chronic phase and was prescribed 100 mg daily
dasatinib. However,
dasatinib was discontinued due to
thrombocytopenia, and within six months, the disease progressed to the lymphoid blastic phase. Hyper-
cyclophosphamide,
vincristine,
adriamycin and
dexamethasone chemotherapy combined with 140 mg
dasatinib or 600 mg
imatinib was prescribed. The two inhibitors were soon discontinued due to severe
thrombocytopenia and
jaundice, respectively. Myelosuppression persisted subsequent to the nadir. Bone marrow (BM) aspiration and biopsy revealed hypercellular marrow filled with blasts. Sequencing of the
leukemia cells revealed overlapping peaks for the wild-type sequence and the T315I mutant sequence. The patient was treated with 500 mg
bosutinib (which was later reduced to 300 mg) for pretransplant cytoreduction. After 5 months, the patient's spleen exhibited a reduction in volume and the percentage of blasts in the BM decreased from 96.1 to 17.5%. The patient successfully underwent cord blood
transplantation. The patient has been disease-free for 5 months subsequent to
transplantation. This case suggests that
bosutinib may be effective for cytoreduction prior to
stem cell transplantation, unless the
leukemia cells consistently harbor the T315I mutation.