Inclusion Criteria:

          -  Willing and able to provide informed consent

          -  Age 18 and older

          -  Diagnosis of AML or MDS according to the WHO criteria

          -  AML relapsed or refractory to at least one attempt at induction or subjects not
             candidates for aggressive induction regimens

          -  MDS refractory to treatment with HMA therapy or with recurrence or progression of MDS
             following a response to an HMA

          -  Has adequate organ function: AST and ALT < 3X the ULN, serum bilirubin < 2X the ULN,
             serum creatinine of < 2 mg/dL, or a calculated creatinine clearance of > 50 mL/minute

          -  ECOG Performance Score of 0 -2

          -  Recovered from the effects of any prior systemic therapy, radiotherapy or surgery

          -  Willing to use physician approved birth control method

        Exclusion Criteria:

          -  Current CNS Leukemia

          -  Acute promyelocytic leukemia or AML with a t(15;17) (q22;q12) cytogenetic abnormality
             or Bcr/Abl positive leukemia

          -  < 60 days from ASCT; has chronic graft-versus host disease (GVHD) or requires
             continued treatment with systemic immunosuppressive agents

          -  Uncontrolled infection

          -  Known HIV, hepatitis B or hepatitis C.

          -  Other active malignancy that requires therapy

          -  If female, is lactating or breast feeding

          -  Hypersensitivity to PEG or other component of AEB1102 (Co-ArgI-PEG)