Inclusion Criteria:

• Diagnosis of Ph-positive or Bcr-positive CML in early chronic phase CML (i.e., time from diagnosis 12 months). Except for hydroxyurea, patients must have received no or minimal prior therapy, defined as <1 month of prior interferon-alpha (with or without cytarabine) and/or imatinib.
• Age >/= 16 years.
• ECOG performance of 0-2.
• Adequate end organ function, defined as the following: total bilirubin < 1.5 x upper limit of normal (ULN); SGPT < 2.5 x ULN; creatinine < 1.5 x ULN.
• Patients must sign an informed consent indicating they are aware of the investigational nature of this study, in keeping with the policies of the hospital.

Exclusion Criteria:

• New York Heart Association (NYHA) cardiac class 3-4 heart disease as well as impaired cardiac function defined as:

  • Left ventricular ejection fraction (LVEF) < 45% as determined by MUGA scan or electrocardiogram;
  • Complete left bundle branch block;
  • Use of cardiac pacemaker;
  • ST depression of > 1 mm in 2 or more leads and/or T wave inversions in 2 or more continuous leads;
  • Congenital long QT syndrome;
  • History of, or presence of significant ventricular or atrial tachyarrhythmias;
  • Clinically significant resting bradycardia (< 50 beats per minute [bpm]);
  • QTc > 450 msec on screening electrocardiogram [ECG] (using the QTcF formula);
  • Right bundle branch block plus left anterior hemiblock, bifascicular block;
  • Myocardial infarction within 12 months prior to starting Nilotinib;
  • Angina pectoris diagnosed or treated within the past 12 months;
  • Other clinically significant heart disease (e.g. congestive heart failure, uncontrolled hypertension, history of labile hypertension, or history of poor compliance with an antihypertensive regimen).
• Patients with active, uncontrolled psychiatric disorders including: psychosis, major depression, and bipolar disorders.
• Female patients of childbearing potential must have negative pregnancy test within 7 days before initiation of study drug dosing. Postmenopausal women must be amenorrheic for at least 12 months to be considered of non-childbearing potential. Surgical sterilization is considered non-childbearing potential. Male and female patients of reproductive potential must agree to employ an effective method of birth control (hormonal or barrier) throughout the study and for up to 3 months following discontinuation of study drug.
• Patients with severe and/or uncontrolled medical disease (i.e., uncontrolled diabetes, chronic renal disease, or active uncontrolled infection [persistent fever and worsening clinical condition]).
• Patient with known chronic liver disease (i.e., chronic active hepatitis, and cirrhosis).
• Patient with known diagnosis of human immunodeficiency virus (HIV) infection.

• Patients in late chronic phase (i.e., time from diagnosis to treatment >12 months) or blastic phase are excluded. Patients with de novo accelerated phase will be treated but analyzed separately. The definitions of CML phases are as follows:

  1. Early chronic phase: time from diagnosis to therapy < 12 months; Late chronic phase: time from diagnosis to therapy > 12 months.
  2. Blastic phase: presence of 30% blasts or more in the peripheral blood or bone marrow.

  3. Accelerated phase CML: presence of any of the following features:

     • Peripheral or marrow blasts 15% or more;
     • Peripheral or marrow basophils 20% or more;
     • Thrombocytopenia < 100 x 10(9)/L unrelated to therapy;
     • Documented extramedullary blastic disease outside liver or spleen due to past causes.
  4. Clonal evolution defined as the presence of additional chromosomal abnormalities other than the Ph chromosome is part of accelerated phase CML. Ph chromosome variants or complex Ph chromosome translocations are not considered to indicate disease acceleration. The investigators have recently found clonal evolution to have a variable prognostic impact and may be suppressed with interferon alpha (IFN-a) therapy. Hence these patients, like others with de novo accelerated phase, will be eligible, and analyzed separately.