Inclusion Criteria:

          -  Patients ≥ 18 years of age

          -  ECOG (Eastern Cooperative Oncology Group) Performance Status 0, 1, or 2

          -  Must have a diagnosis of Philadelphia chromosome positive (Ph+) chronic myeloid
             leukemia (CML) in chronic phase, with no previous evidence of accelerated or
             blast-phase disease.

          -  Must be actively receiving treatment for their CML with a tyrosine kinase inhibitor
             (TKI): imatinib, dasatinib, nilotinib or bosutinib, and must be on stable dose for > 1
             year.

          -  Must have an ongoing complete hematologic response (CHR) on a TKI

          -  Must have an ongoing complete cytogenetic response (CCyR) on a TKI

          -  Must be in a major molecular remission (MMR) on a TKI for a minimum of 1 year leading
             up to enrollment.

          -  Adequate end organ function

          -  Adequate electrolytes

          -  Adequate platelet count

          -  Adequate neutrophil count

          -  Written informed consent prior to any screening procedures

        Exclusion Criteria:

          -  Patients in complete molecular remission (CMR) on a TKI.

          -  Patients who have failed nilotinib or not tolerated nilotinib in the past

          -  Certain cardiovascular disorders

          -  Currently receiving treatment with strong CYP3A4 inhibitors which cannot be
             discontinued prior to starting study drug

          -  Actively receiving herbal medicines that are strong CYP3A4 inhibitors and/or inducers
             and treatment cannot be discontinued prior to starting study drug

          -  Currently receiving treatment with any medications that have the potential to prolong
             the QT interval that cannot be discontinued prior to starting study drug

          -  Impaired gastrointestinal (GI) function or GI disease that may significantly alter the
             absorption of the drug

          -  Acute or chronic pancreatic disease within the last year

          -  Cytopathologically confirmed Central Nervous System (CNS) infiltration

          -  Another primary malignancy that requires systemic chemotherapy or radiation

          -  Acute or chronic liver disease or severe renal disease considered unrelated to the
             cancer

          -  History of significant congenital or acquired bleeding disorder unrelated to cancer

          -  Major surgery within 4 weeks prior to Day 1 of the study or who have not recovered
             from prior surgery

          -  Past treatment with ruxolitinib

          -  Treatment with other investigational agent within 30 days of Day 1

          -  Inability to grant consent or history of non-compliance to medical regimens

          -  Women who are breastfeeding

          -  Women of child-bearing potential, unless they are using highly effective contraception