Study Comparing Standard Dose and High-dose Imatinib Mesylate in Patients With Chronic Phase Philadelphia Chromosome Positive (Ph+) Chronic Myelogenous Leukemia (CML)

Inclusion Criteria: * Chronic myelogenous leukemia with Philadelphia chromosome * 18 years and older * Patients must have been taking imatinib mesylate standard dose for at least 12 months and have achieved a complete cytogenetic response but not a major molecular response. Exclusion Criteria: * Patients with cardiac problems such as congestive heart failure, or myocardial infarction within the last 6 months * Patients with an uncontrolled medical disease such as uncontrolled diabetes, chronic renal (kidney) disease or active uncontrolled infection. * Patients with other current primary malignancy or malignancy requiring active intervention Other protocol defined inclusion/exclusion criteria may apply.