Nilotinib vs Imatinib in Adult Patients With Philadelphia (Ph+) Chronic Myelogenous Leukemia in Chronic Phase (CML-CP)

Inclusion criteria: Diagnosis of Philadelphia chromosome positive chronic myelogenous leukemia in the chronic phase. Patients with suboptimal cytogenetic response to a dose of 400 mg imatinib (first line therapy) defined as: * 6 to \< 12 months of treatment and -have 36 - 95% Ph+ metaphases, or * 12 to \<18 months of treatment and have 1 - 35% Ph+ metaphases (Standard cytogenetics, no FISH \[fluorescence in situ hybridization\] analysis was allowed). Exclusion criteria: * Patient who have received more than 18 months of imatinib therapy * Patients who have achieved partial or complete cytogenetic response and lost that response prior to entering the study. * Prior treatment with greater than 400 mg/day imatinib. * Uncontrolled or significant cardiovascular disease. * Severe or uncontrolled medical conditions (i.e. uncontrolled diabetes, active or uncontrolled infection). * Use of therapeutic coumarin derivatives (i.e., warfarin, acenocoumarol, phenprocoumon) * Currently taking certain medications that could affect the rhythm of your heart. Other protocol-defined inclusion/exclusion criteria may apply