**5.1 Imatinib (Gleevec)**

Imatinib mesylate (IM), a phenylaminopyrimidine TKI that is the first drug of its class characterized by BCR-ABL TKI has excellent changes in the strategy of treatment of CML in the last 20 years. In May 2001, FDA has approved imatinib for the treatment of CML patients. Arthralgia, myalgia, nausea, and fluid retention are the common side effects in imatinib. About 97% complete hematologic response and 83% cytogenetic response was documented after many years of regular follow up of CML patients received imatinib [36, 37]. Patients with hematological or cytogenetic resistance to standard dosage of imatinib (400 mg) were begun with tall dosage (600–800 mg). Some of patients are unlikely to be overcome by high doses due to some specific mutations, in these cases alternative target therapy should be considered for patients fails or with suboptimal response [38].
