Inclusion Criteria:

   1. Male or female subjects ≥ 55 years of age

   2. Newly diagnosed, histologically confirmed de novo AML or AML secondary to prior
   myelodysplastic disease or CMML (Chronic myelomonocytic leukemia)

   3. First Complete remission (CR)/ Complete remission with incomplete blood count recovery
   (CRi) with induction therapy + consolidation therapy within 4 months (+/- 7 days of
   achieving CR or CRi)

   4. Eastern Cooperative Oncology Group (ECOG) performance status - 0, 1, 2, 3

Inclusion Criteria in the Extended Phase of the study:

At the Investigator's discretion and with approval of the sponsor, subjects meeting all of
the following eligibility criteria are eligible to enter the extension phase:

   1. All subjects randomized into the oral azacitidine or placebo arm and are continuing in
   either the Treatment Phase or Follow-up Phase of the CC-486-AML-001 study;

      - Subjects randomized to oral azacitidine treatment arm and continuing in the
      Treatment Phase demonstrating clinical benefit as assessed by the Investigator
      are eligible to receive oral azacitidine in the EP;

      - Subjects randomized into placebo arm of the study will not receive oral
      azacitidine in the EP, but will be followed for survival in the EP;

      - Subjects currently in the in the Follow-up Phase will continue to be followed for
      survival in the EP;

   2. Subjects who have signed the informed consent for the EP of the study;

   3. Subjects who do not meet any of the criteria for study discontinuation

Exclusion Criteria:

   1. AML with inv(16), t(8;21), t(16;16), t(15;17), or t(9;22) or molecular evidence of
   such translocations

   2. Prior bone marrow or stem cell transplantation

   3. Have achieved CR/CRi following therapy with hypomethylating agents

   4. Diagnosis of malignant disease within the previous 12 months

   5. Proven Central Nervous System (CNS) leukemia