Targeting the bone marrow microenvironment in acute leukemia.

Despite individual differences between certain leukemias, the overall survival rate in acute leukemia remains low at approximately 40%. Novel therapeutics, including targeted therapies like tyrosine kinase inhibitors, have been incorporated into treatment regimens, but most have failed at eradicating leukemic stem cells (LSCs). The causes of disease relapse, progression, and resistance to chemotherapy are as yet not entirely clear but thought to be linked to protection in the bone marrow microenvironment (BMM). In this review, we summarize current knowledge on the BMM in acute leukemias and examine the ongoing efforts to target the BMM, which include treatment strategies targeting (a) leukemia-BMM interactions, (b) leukemia-cell intrinsic pathways influenced by the BMM, and (c) direct BMM targeting strategies. It is likely that the future ploy against leukemia will involve these and other innovative strategies designed to eradicate the last remaining warrior - the LSC.