Inclusion Criteria:

          -  Males and females ≥ 18 years of age

          -  Phase 1: Confirmed relapsed or refractory AML with a documented FLT3 and/or Ras
             mutation, or ≥ 60 years with newly diagnosed FLT3+ and/or Ras+ AML and not eligible
             for standard induction chemotherapy or FLT3+ and/or Ras+ higher-risk MDS/CMML (defined
             as ≥ 10% marrow blasts or ≥ 5% peripheral blood blasts or Revised International
             Prognostic Scoring System [IPSS-R] score ≥ 3.5) and relapsed or refractory to prior
             therapy

          -  Phase 2: Confirmed relapsed or refractory AML with a documented FLT3 and/or Ras
             mutation, or age ≥ 60 years with newly diagnosed FLT3+ and/or Ras+ AML and not
             eligible for standard induction chemotherapy

          -  At least 3 weeks beyond the last cancer treatment for the disease under study, major
             surgery and recovered from all acute toxicities (≤ Grade 1) by first dose of study
             drug (C1D1). Hydroxyurea used to control peripheral blast counts is permitted during
             the first 2 cycles.

          -  Adequate performance status Eastern Cooperative Oncology Group (ECOG) ≤ 2

          -  Adequate renal and hepatic function:

               -  creatinine ≤ 1.5 mg/dL OR calculated creatinine clearance ≥ 45 mL/minute

               -  total bilirubin ≤ 2 times the upper limit of normal (ULN) unless due to Gilbert's
                  disease or thought to be due to underlying AML

               -  ALT and AST ≤ 5 times ULN

          -  Negative serum pregnancy test within 14 days prior to the first dose of study therapy
             for women of child-bearing potential (WCBP). Sexually active WCBP and male subjects
             must agree to use adequate methods to avoid pregnancy throughout the study and for 28
             days after completion of study treatment.

          -  Ability to provide written informed consent

        Exclusion Criteria:

          -  History of clinically significant cardiac impairment, congestive heart failure (CHF)
             New York Heart Association (NYHA) Class III or IV, unstable angina, or myocardial
             infarction during the previous 6 months, or serious cardiac arrhythmia

          -  QT interval corrected for rate (QTc) ≥ 450 msec for males and ≥ 460 msec for females
             on the ECG obtained at Screening using Fridericia method for QTc calculation (average
             of 3 readings)

          -  Concomitant medication(s) that may cause QTc prolongation or induce Torsades de
             Pointes with the exception of anti-microbials used as standard of care to prevent or
             treat infections and other such drugs that are considered by the investigator to be
             essential for the care of the patient. However, if such medications are deemed to be
             necessary during the study, more extensive ECG monitoring will be added during the
             period of concomitant drug administration.

          -  Presence of active central nervous system (CNS) leukemia. Subjects adequately treated
             for CNS leukemia documented by 2 consecutive cerebrospinal fluid samples negative for
             leukemia cells are eligible. Subjects with no history of CNS leukemia will not be
             required to undergo cerebrospinal fluid sampling for eligibility.

          -  Known positive for human immunodeficiency virus (HIV), hepatitis B virus surface
             antigen (HBsAg), or hepatitis C virus HCV)

          -  Active, uncontrolled infection

          -  Known hypersensitivity to any study drug component

          -  History of another malignancy; Exception: Patients disease-free for 2 years or treated
             in situ carcinoma

          -  Any other medical intervention or other condition which, in the opinion of the
             Principal Investigator, could compromise adherence to study requirements or confound
             the interpretation of study results

          -  Pregnancy or lactation