Targeting chronic myeloid leukemia stem cells

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder that is characterized by the presence of the fusion oncogene BCR-ABL that encodes the tyrosine kinase BCR-ABL. Constitutive expression of BCR-ABL leads to the unregulated production of mature myeloid cells in the bone marrow and their subsequent release into the blood. Untreated, CML will progress from a chronic to accelerated phase over a number of years before quickly proceeding to a terminal blast crisis phase, reminiscent of acute leukemia. The advent of tyrosine kinase inhibitors has led to much improved management of the disease, but these drugs do not provide a cure as they are unable to eradicate the most primitive, quiescent fraction of CML stem cells. This review looks at recent research into targeting CML stem cells and focuses on major signalling pathways of interest.