Key Inclusion Criteria:

          -  Part A: Patients with relapsed or refractory AML, or newly-diagnosed AML secondary to
             MPN

          -  Part B:Patients with relapsed or refractory AML secondary to MPN (myelofibrosis [MF],
             polycythemia vera [PV], or essential thrombocythemia [ET]); patients may have been
             treated with ≥1 prior lines of therapy for their AML secondary to MPN.

          -  Adequate hepatic and renal function

          -  Appropriate prior treatment with an FLT3 or IDH1/2 inhibitor where applicable

        Key Exclusion Criteria:

          -  Patients who are TP53 mutation positive

          -  Prior treatment with an MDM2 antagonist therapy

          -  Patients treated with ≥ 18 g/m2 of cytarabine within the prior 90 days are not
             eligible to be treated with cytarabine on this study but may be treated with
             decitabine (for Part A) .

          -  Patients previously treated with decitabine are not eligible to receive decitabine on
             this study but may be treated with cytarabine (for Part A) .

          -  Patients who have received an allogeneic HSCT within 90 days of enrollment or who have
             active graft-versus-host disease requiring active therapy (for Part A)

          -  Allogeneic stem cell transplant within 3 months; autologous stem cell transplant
             within 3 months or active graft-versus-host disease prior to first dose of study
             treatment (for Part B)

          -  Patients who have received immunosuppressive therapy for graft-versus-host disease
             within 1 month prior to enrollment into this study

          -  Patients who are eligible for an allogeneic HSCT per the opinion of the investigator
             and have a donor. Patients who are HSCT-eligible in the opinion of the investigator,
             but who refuse a transplant, are eligible for the study.

          -  Patients with known CNS involvement with AML, acute promyelocytic leukemia (APL), or a
             history of bleeding diathesis

          -  Patients who have had major surgery within 28 days prior to the first treatment with
             KRT-232

          -  Women who are pregnant or breastfeeding