Inclusion Criteria:

          1. A history of AML or MDS with at least one of the following features:

             AML: High-risk AML as defined by the 2017 European LeukemiaNet criteria (e.g. complex
             karyotype with ≥3 changes), AML with high-risk mutations (e.g. TP53, RUNX1, or ASXL1
             mutations), transplant being performed in second remission or beyond, or AML with
             active disease or minimal residual disease positivity before or after transplant.

             MDS: MDS with high or very-high risk cytogenetic changes as used indefined by the
             Revised International Prognostic Scoring System (e.g. complex karyotype with ≥3
             changes),53 the presence of TP53 mutation, high-risk or very high-risk MDS not
             responding to 4 cycles of hypomethylating agents, MDS progressing following initial
             response, persistence of MDS after transplant, or transplant being performed in second
             remission or beyond.

          2. Receipt of allogeneic hematopoietic stem cell transplant 6-20 weeks prior to
             enrollment

          3. Disease status: <5% bone marrow blast at the time of enrollment

          4. All donor sources and conditioning regimens are allowed

          5. Adults, Age ≥19 years (for the state of Nebraska)

          6. Karnofsky Performance Status (KPS) of ≥70

          7. Absolute neutrophil count (ANC) greater than 1000/µL without the use of granulocyte
             colony stimulating factor in the past 2 weeks, and platelet count ³75,000/µL without
             platelet transfusion in the past 2 weeks.

          8. Able to take oral medication.

          9. Female patient of reproductive potential must have a negative serum or urine pregnancy
             test ≤7 days prior to starting the study drug.

         10. Male and female patients of reproductive potential must be willing to avoid pregnancy
             or fathering children from enrollment to two months after the end of study treatment.
             This will require either a total abstinence, OR exclusively non-heterosexual activity
             (when this is in line with the preferred and usual lifestyle of the subject), OR two
             methods of contraception

         11. Written informed consent to participate in the study.

        Exclusion Criteria:

          1. A history of acute graft-versus-host disease grade III/IV or initiation of any new
             immunosuppressive agent for treatment of graft-versus-host disease within 4 weeks
             prior to enrollment. Oral beclomethasone or budesonide, empirically used for possible
             but not biopsy-proven graft-versus-host disease, will not be considered an exclusion
             criterion.

          2. Use of prednisone at a dose of ≥0.25 mg/kg/day (or equivalent dose of another
             glucocorticoid) at the time of enrollment

          3. Active uncontrolled bacterial, fungal, parasitic, or viral infection. Infections are
             considered controlled if appropriate therapy has been instituted and, at the time of
             screening, no signs of infection progression are present. Progression of infection is
             defined as hemodynamic instability attributable to sepsis, new symptoms, worsening
             physical signs or radiographic findings attributable to infection. Persisting fever
             without other signs or symptoms will not be interpreted as progressing infection

          4. Presence of known HIV infection, active hepatitis B or C infection.

          5. Total bilirubin, aspartate transaminase, alanine transaminase 2 ´ the upper limit of
             the normal range. Patients with elevated bilirubin secondary to Gilbert syndrome will
             not be excluded.

          6. Creatinine clearance <30 mL/min

          7. Presence of uncontrolled cardiopulmonary conditions such as ongoing cardiac
             arrhythmias, unstable angina or myocardial infarction, New York Heart Association
             class III/IV congestive heart failure, or severe chronic obstructive pulmonary disease
             or other pulmonary condition resulting in a requirement of supplemental oxygen or
             having a resting O2 saturation <90% by pulse oximetry

          8. Pregnancy or breastfeeding.

          9. Known hypersensitivity, or intolerance to any of the study medications, or excipients.

         10. Treatment with any other investigational agent, device, or procedure, within 21 days
             (or 5 half-lives, whichever is greater)

         11. Patients on dopamine antagonists for treatment of psychotic disorder or Parkinson's
             disease will be excluded. A brief use of drugs such as clozapine or haloperidol for a
             few days for treatment of nausea or other indication will not be prohibited. The use
             of tricyclic antidepressants does not constitute an exclusion criterion.

         12. Any other condition that is judged by the physician to potentially interfere with
             compliance to the study protocol or pose a significant risk to the patient.