Imatinib Mesylate is believed to work by interfering with the abnormal protein by blocking it from telling the body to keep making more and more abnormal white blood cells. Imatinib Mesylate is approved by the FDA for the treatment of chronic myeloid leukemia (CML) and some types of acute lymphoblastic leukemia (ALL). Its use in combination with CLAG regimen is considered experimental for the treatment of Acute Myeloid Leukemia / CML blast crisis