Inclusion Criteria:

   1. Confirmed diagnosis of primary or secondary AML (any subtype except acute
   promyelocytic leukemia) according to World Health Organization (WHO) 2016
   classification

   2. Unlikely to benefit from standard of care therapy defined by any one of the following
   criteria:

      1. Primary induction failure (PIF) defined as leukemia refractory to ≥ 1 induction
      attempts. Induction attempts include 1 high-dose and/or 2 standard-dose
      cytarabine

         - an anthracyclines/anthracenedione ± an anti-metabolite, with or without
         growth factor or targeted therapy containing regimens.

      2. For adults who are age 75 years or older, or who have comorbidities that preclude
      use of intensive induction chemotherapy; PIF is defined as AML refractory to one
      of the following less intensive regimens:

         - ≥ 2 but ≤ 4 cycles of Bcl-2 inhibitors in combination with azacitidine,
         decitabine, or low dose cytarabine

         - ≥ 2 but ≤ 4 cycles of gemtuzumab ozogamicin monotherapy

         - ≥ 6 but ≤ 8 cycles ivosidenib or enasidenib

      3. Leukemia in relapse after achieving CR

         - Early Relapse: disease recurrent within ≤ 6 month of documented remission

         - Late Relapse: disease recurrent within > 6 month of documented remission

         - Refractory-Relapse: refractory to ≥ 1 unsuccessful salvage attempts

   3. Patients with AML post hematopoietic stem cell transplant (HSCT) [permitted in Cohort
   Expansion Phase only] must meet the following criteria:

      - There must be histological confirmation of AML relapse after HSCT

      - Undergone allogeneic HSCT (alloSCT) > 90 days prior to enrollment from a match
      related donor, matched unrelated donor, cord blood donor, or haplo- identical
      donor

      - Off all immunosuppressive medications for a minimum of 2 weeks with the exception
      of physiologic doses (<10 mg) of corticosteroids

      - No history of Grade ≥ 3 veno-occlusive disease, or active graft versus host
      disease

   4. Patients with known central nervous system (CNS) involvement with AML are eligible if
   they have been treated and cerebrospinal fluid is clear for at least 2 weeks prior to
   enrollment into the study. CNS therapy (radiotherapy or chemotherapy) should continue
   as medically indicated during the study treatment.

   5. Patients with extramedullary disease are permitted if bone marrow blast count is >5%

   6. Adequate organ function as defined in the protocol

   7. Life expectancy >12 weeks

   8. Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 2 at screening

Exclusion Criteria:

   1. Circulating blast count >30,000/µL by morphology or flow cytometry (cytoreductive
   therapies such as leukapheresis or hydroxyurea are allowed)

   2. Uncontrolled or untreated bacterial, fungal, or viral infections, including HIV,
   Hepatitis B or C infection, or uncontrolled infection of any etiology

   3. Uncontrolled angina, severe uncontrolled ventricular arrhythmias, or electrocardiogram
   (ECG) suggestive of acute ischemia or active conduction system abnormalities

   4. Severe renal impairment, defined as creatinine clearance <40 mL/min

   5. New progressive pulmonary infiltrates on screening chest x-ray or chest CT scan that
   have not been evaluated with bronchoscopy. Infiltrates attributed to infection must be
   stable/improving after 1 week of appropriate therapy (4 weeks for presumed or proven
   fungal infections).

   6. Known hypersensitivity to one or more of the study agents

   7. Received any investigational drugs within the 14 days prior to the first dose of
   fludarabine (wash-out period of at least 5 half-lives from the last dose of any
   investigational therapy prior to screening period or 14 days, whichever is longer)

   8. Pregnant or nursing (lactating) women

   9. Any condition that, in the opinion of the Investigator, would prevent the participant
   from consenting to or participating in the study