Inclusion Criteria:

          1. Male or female patients ≥ 18 years of age with a confirmed diagnosis of Chronic
             Myeloid Leukemia in chronic phase (CML-CP).

          2. Minimum of one year (12 calendar months) treatment with imatinib first line for CML-CP
             (patients have to be on imatinib 400 mg QD at randomization and had no dose change in
             the past three months).

             For Korea only: (i)a minimum of one year (12 calendar months) of prior treatment with
             imatinib for patients with BCR-ABL levels > 0.1%, ≤ 1% IS at the time of
             randomization. (ii) a minimum of two years (24 calendar months) of prior treatment
             with imatinib for patients with BCR-ABL levels > 0.01%, ≤ 0.1% IS at the time of
             randomization.

          3. BCR-ABL1 levels > 0.01% IS (International Scale) and ≤ 1% IS at the time of
             randomization as confirmed with a central assessment at screening; patients must not
             have achieved deep molecular response (MR4 IS) confirmed by 2 consecutive tests at any
             time during prior imatinib treatment. An isolated, single test result with BCR-ABL1
             levels < 0.01 % (MR4 IS) is allowed, however, it should not have been observed within
             the 9 months prior to randomization

          4. Patient must meet the following laboratory values before randomization:

               -  Absolute Neutrophil Count ≥ 1.5 x 10E9/L

               -  Platelets ≥ 75 x 10E9/L

               -  Hemoglobin ≥ 9 g/dL

               -  Serum creatinine < 1.5 mg/dL

               -  Total bilirubin ≤ 1.5 x ULN (Upper Limit of Normal) except for patients with
                  Gilbert's syndrome who may only be included with total bilirubin ≤ 3.0 x ULN

               -  Aspartate transaminase (AST) ≤ 3.0 x ULN

               -  Alanine transaminase (ALT) ≤ 3.0 x ULN

               -  Alkaline phosphatase ≤ 2.5 x ULN

               -  Serum lipase ≤ 1.5 x ULN

          5. Patients must have the following laboratory values ≥ Lower Limit of Normal or
             corrected to within normal limits with supplements prior to randomization: potassium
             increase of up to 6.0 mmol/L is acceptable if associated with creatinine clearance
             within normal limits ; calcium increase of up to 12.5 mg/dl or 3.1 mmol/L is
             acceptable if associated with creatinine clearance* within normal limits) ; magnesium
             increase up to 3.0 mg/dL or 1.23 mmol/L if associated with creatinine clearance within
             normal limits.

        Key Exclusion Criteria:

          1. Treatment failure according to European Leukemia Network (ELN) criteria 2013 during
             imatinib treatment.

          2. Known second chronic phase of CML after previous progression to Accelerated Phase
             (AP)/Blast Crisis (BC).

          3. Previous treatment with any tyrosine kinese inhibitors (TKIs) other than imatinib.

          4. History or current diagnosis of ECG abnormalities indicating significant risk or
             safety for subjects participating in the study such as:

               -  History of myocardial infarction, angina pectoris, coronary artery bypass graft
                  within 6 months prior to randomization

               -  Concomitant clinically significant arrhythmias

               -  Resting QTcF ≥ 450 msec (male) or ≥ 460 msec (female) prior to randomization

               -  Long QT syndrome, family history of idiopathic sudden death or congenital long QT
                  syndrome, or any of the following:

                    -  Risk factors for Torsades de Pointes

                    -  Concomitant medications with a "known" risk of Torsades de Pointes

                    -  inability to determine the QTcF interval

          5. Severe and/or uncontrolled concurrent medical disease that in the opinion of the
             investigator could cause unacceptable safety risks or compromise compliance with the
             protocol (e.g. uncontrolled diabetes, active or uncontrolled infection, uncontrolled
             clinically significant hyperlipidemia and high serum amylase)

          6. History of acute pancreatitis within 1 year prior to randomization or medical history
             of chronic pancreatitis; on-going acute liver disease or history of chronic liver
             disease

          7. History of other active malignancy within 3 years prior to randomization with the
             exception of basal cell skin cancer, indolent prostate cancer and carcinoma in situ
             treated curatively.

        Other protocol defined inclusion/exclusion may apply.