Inclusion Criteria:

- Men and women ≥18 years diagnosed with Chronic Phase Philadelphia chromosome positive
(CP Ph+) CML who have failed to achieve CCyR after 3-18 months of therapy with
imatinib 400 mg

- Treatment initiation with imatinib 400 mg within 6 months of initial CML diagnosis

- Able to tolerate chronic administration of imatinib at the highest dose (400-600 mg)
the subject has received in the past

- Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0-2

- Adequate hepatic and renal function

Exclusion Criteria:

- Eligible and willing to undergo immediate autologous/allogeneic stem cell transplant

- Previous diagnosis of accelerated/blast crisis CML

- Subjects with clonal evolution in Ph+ cells observed in ≥2 metaphases

- Previous documentation of T315I mutation

- Uncontrolled or significant cardiovascular disease

- Serious uncontrolled medical disorder/active infection

- History of significant bleeding disorder unrelated to CML

- Intolerance to imatinib ≥400 mg

- Concurrent malignancies other than CML