<qa>  What is the effect of giving imatinib mesylate together with decitaThis phase II trial is studying how well giving imatinib mesylate together with decitabine works in treating patients with accelerated or blast phase chronic myelogenous leukemia. Imatinib mesylate may stop the growth of cancer cells by blocking the enzymes necessary for cancer cell growth. Drugs used in chemotherapy use different ways to stop cancer cells from dividing so they stop growing or die. Giving imatinib mesylate together with decitabine may kill more cancer cells 