1. Written informed consent must be obtained prior to any screening procedures

          2. Male or female patients ≥ 18 years of age who present with one of the following:

             Arms 1-3:

               -  Refractory/relapsed AML following ≥1 prior therapies and are deemed by the
                  investigator not to be candidates for standard therapy, including re-induction
                  with cytarabine or other established chemotherapy regimens for patients with AML
                  (patients who are suitable for standard re-induction chemotherapy or
                  hematopoietic stem cell transplantation and willing to receive it are excluded)

               -  De novo AML patients who are suitable for treatment with decitabine (patients who
                  are suitable for standard induction chemotherapy or hematopoietic stem cell
                  transplantation and willing to receive it are excluded)

               -  High risk MDS (patients who are suitable for standard re-induction chemotherapy
                  or hematopoietic stem cell transplantation and willing to receive it are
                  excluded)

             Arms 4-5:

               -  Refractory / relapsed AML following ≥1 prior therapies (Arms 4a & 5a)

               -  High risk MDS who have failed hypomethylating agent therapy (Arms 4b & 5b) (Note:
                  hypomethylating agent failure is defined as progressive disease on
                  hypomethylating agent therapy or lack of clinically meaningful response as deemed
                  by investigator after at least 4 cycles of hypomethylating agent therapy.)

          3. Patient has an Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2

          4. Patient must be a candidate for serial bone marrow aspirate and/or biopsy according to
             the institutions guidelines and be willing to undergo a bone marrow aspirate
             and/biopsy at screening, during and at the end of therapy on this study. Exceptions
             may be considered after documented discussion with Novartis.

          5. Arms 1-3: Patients must be fit for standard treatment with decitabine as determined by
             the investigator and as per local decitabine package insert.