Inclusion Criteria:

- Age 18 years or older at the time of signing the informed consent document

- Diagnosis of Myelodysplastic Syndromes, Chronic Myelomonocytic Leukemia and Acute
Myeloid Leukemia

- Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2

- At least 3 month life expectancy

- Adequate organ function, defined as:

- Serum bilirubin ≤ 1.5 times the upper limit of normal (ULN);

- Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5
times the ULN;

- Serum creatinine ≤ 1.5 times the ULN;

- Serum bicarbonate ≥ 20 mEq/L

- Females of childbearing potential (FCBP) must:

- Agree to use at least two effective contraceptive methods (oral, injectable, or
implantable hormonal contraceptive; tubal ligation; intra-uterine device;
barrier contraceptive with spermicide; or vasectomized partner) throughout the
study, and for 3 months following the last dose of oral azacitidine; and

- Have a negative serum or urine pregnancy test (investigator's discretion;
sensitivity of at least 25 mIU/mL) at screening; and

- Have a negative serum or urine pregnancy test (investigator's discretion;
sensitivity of at least 25 mIU/mL) within 72 hours prior to Day 1 of the
pharmacokinetic (PK) phase (note that the screening pregnancy test can be used
as the test prior to Day 1 of the PK phase if it is performed within the 72 hour
timeframe).

- Males with partners who are FCBP must agree that they and their partners will use at
least two effective contraceptive methods throughout the study and will avoid
fathering a child for 3 months following the date of last oral azacitidine dosing

- Understand and voluntarily sign an informed consent document prior to the start of
any study related assessments/procedures

- Able to adhere to the study visit schedule and other protocol requirements

Exclusion Criteria:

- Suspected or proven acute promyelocytic leukemia based on morphology,
immunophenotype, molecular assay, or karyotype

- Previous treatment with azacitidine or other demethylating agents within 21 days
prior to starting study therapy or ongoing adverse events from previous treatment,
regardless of the time period

- Anticancer therapy (standard or investigational) within 21 days prior to starting
study therapy or ongoing adverse events from previous treatment, regardless of the
time period

- Use of any proton pump inhibitor or any other agent that may affect gastric acid
level within 28 days prior to study therapy (only applicable to Part II of the PK
phase)

- Concurrent use of erythropoiesis-stimulating agents (ESAs) and other red blood cell
hematopoietic growth factors, except that the subject is on a stable dose for at
least 4 weeks (28 days) prior to starting study therapy

- Concurrent use of iron-chelating agents, except that the subject is on a stable dose
for at least 8 weeks (56 days) prior to starting study therapy

- Concurrent corticosteroid use, except for medical conditions other than
Myelodysplastic Syndrome and provided the subject is on a stable or decreasing dose
for ≥ 1 week prior to start study therapy

- Pregnant or lactating females

- Any known or suspected hypersensitivity to azacitidine or mannitol or any other
ingredient used in the manufacture of oral azacitidine (see the azacitidine IB)

- Uncontrolled systemic fungal, bacterial, or viral infection (defined as ongoing
signs/symptoms related to the infection without improvement despite appropriate
antibiotics or other treatment)

- Active viral infection with known human immunodeficiency virus (HIV) or viral
hepatitis type B or C

- Presence of gastrointestinal disease, malignant hepatic tumors, or other conditions
known to interfere with the absorption, distribution, metabolism, or excretion of
drugs

- Current congestive heart failure (New York Heart Association Class III-IV Appendix
G), unstable angina or angina requiring surgical or medical intervention within 6
months prior to starting study therapy, myocardial infarct within 6 months prior to
starting study therapy, or uncontrolled cardiac arrhythmia (defined as arrhythmia
that is symptomatic or requires treatment or asymptomatic sustained ventricular
tachycardia). Subjects with controlled atrial fibrillation that is asymptomatic are
eligible

- Any significant medical condition, laboratory abnormality, or psychiatric illness
that would prevent the subject from participating in the study

- Any condition, including the presence of laboratory abnormalities, which places the
subject at unacceptable risk if he/she were to participate in the study

- Any condition that confounds the ability to interpret data from the study