Inclusion Criteria

          1. Patients 18 years or older

          2. Part I: Patients with one of the following histologically- or cytologically-proven
             conditions: relapsed/refractory AML, relapsed/refractory MDS, or advanced CML in AP or
             BP (i.e., Acute Group patients).

          3. Part II: Patients with one of the following documented conditions: CML in CP that is
             Philadelphia chromosome (Ph)-positive (by cytogenetics) or BCR-ABL1-positive by
             fluorescent in situ hybridization [FISH], or PCR), as well as resistant to at least 2
             FDA-approved tyrosine kinase inhibitors (TKIs); or a myeloproliferative neoplasia
             which includes: PMF and myelofibrosis secondary to polycythemia vera (PV) and
             essential thrombocythemia (ET) myelofibrosis (MF) (with intermediate-1, intermediate-2
             or high risk disease according to the International Working Group [IWG] prognostic
             scoring system) (i.e., Non-Acute Group patients).

          4. Part III:

               -  Arm A: Patients with AML who are 65 years of age or older with refractory or
                  relapsed disease, or who have not received prior therapy but are not eligible to
                  receive intensive frontline chemotherapy (i.e., Acute Group patients);

               -  Arm B: Patients with CML in AP or BP, either newly diagnosed or failing TKI
                  therapy (i.e., Acute Group patients);

               -  Arm C: Patients with CML in CP after failure of 2 FDA-approved TKIs (i.e.,
                  Non-Acute group patients)

          5. Performance status 0-2 of the Eastern Cooperative Oncology Group (ECOG) scale

          6. Patients must have been off all prior therapy for leukemia except hydroxyurea for 1
             week prior to entering this study and recovered from the toxic effects of that therapy

          7. Adequate organ function as defined by:

               -  Serum creatinine ≤ 2.0 mg/dL or calculated creatinine clearance ≥60 mL/min

               -  Total bilirubin ≤2 x ULN (≤5 x ULN if considered due to Gilbert's syndrome or
                  hemolysis)

               -  Alanine aminotransferase (ALT) ≤3xULN

          8. Patients must sign an informed consent indicating that they are aware of the
             investigational nature of this study.

          9. Women of childbearing potential and men should practice effective methods of
             contraception. Women of childbearing potential should have a negative urine or serum
             pregnancy test (minimum sensitivity 25 IU/L or equivalent units of human chorionic
             gonadotropin within 7 days prior to the start of PRI 724.

        Exclusion Criteria

          1. Patients receiving any other investigational agents

          2. Patients who are pregnant or breast-feeding

          3. Known hypersensitivity to any of the components of PRI-724

          4. Pretreatment QTcF interval >470 msec (females) or >450 msec (males)

          5. Known active hepatitis B, hepatitis C

          6. Serious uncontrolled medical disorder or active systemic infection or current unstable
             or decompensated medical condition, which makes it undesirable or unsafe for the
             patient to participate in the study including: New York Heart Association (NYHA) Class
             3 or 4, myocardial infarction within 3 months, uncontrolled angina within 3 months,
             history of clinically significant ventricular arrhythmia, diabetes mellitus with
             ketoacidosis, or chronic obstructive pulmonary disease (COPD) requiring
             hospitalization in 6 months prior to the start of treatment with PRI-724.

          7. Any other condition, including mental illness or substance abuse deemed by the
             Investigator to be likely to interfere with a patient's ability to sign informed
             consent, cooperate, and participate in the study

          8. Patients on full dose anticoagulants or any dose of warfarin; patients on prophylactic
             dose of low-molecular weight or unfractionated heparin are allowed.

          9. Patients who have demonstrated intolerance to dasatinib 100 mg daily will not be
             eligible for Part III/Arm B or C of the study.