Methods and compositions for identifying leukemic stem cells

A method of treating a subject having or diagnosed with acute lymphocytic leukemia (ALL) or lymphoid blast crisis chronic myeloid leukemia (LBC CML) at increased risk of dying from ALL or LBC CML, comprising:

• (a) obtaining a biological cell sample from the subject;
• (b) isolating mononuclear cells from the sample of (a);
• (c) allowing the cells of (b) to take up a fluorescence substrate for the enzyme aldehyde dehydrogenase (ALDH) and labeling the cells with an anti-CD34 monoclonal antibody and an anti-CD38 monoclonal antibody;
• (d) isolating CD34+CD38− mononuclear cells from the cells of (c) using flow cytometry;
• (e) measuring the ALDH activity of the cells of (d);
• (f) comparing the levels of ALDH activity in the cells of (e) with the levels of ALDH activity in the cells of a control sample from a subject that does not have ALL or LBC CML;
• (g) identifying the cells of (f) that have an intermediate level of ALDH activity (CD34+CD38− ALDHint) in the sample from the subject when compared to the level of ALDH activity of the CD34+CD38− cells in the control sample as being leukemia stem cells (LSCs);
• (h) administering to the subject a treatment for ALL or LBC CML, selected from immunotherapy, an antibody-based therapy, hematopoietic stem cell transplantation, a tyrosine kinase inhibitor that targets a BCR/ABL mutation and/or chimeric antigen receptor T cell therapy, with or without chemotherapy, to decrease the subject's risk of dying from ALL or LBC CML;
• (i) repeating steps (a) through (f);
• and
• (j) determining that the subject has completed treatment for ALL or LBC CIVIL and is at decreased risk of dying from ALL or LBS CML when the presence of LSCs is not detected.