The purpose of this study is to determine how the body absorbs decitabine when taken orally in patients with Myelodysplastic Syndrome (MDS). Safety will also be assessed for this oral dose.

Cohorts are dosed sequentially, and escalation may stop before the 5th cohort is dosed. Each cycle will be approximately 4 weeks in length. Following Cycle 1, patients may receive an additional 4 follow-up cycles of decitabine. Cycles 2-5 will include a 20 mg/m^2 1-hour IV infusion of decitabine on Days 1-5 for all cohorts.

Inclusion Criteria:

1. Histologically confirmed de novo or secondary MDS.
2. Age greater than or equal to 18 years.
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2.
4. Adequate renal and hepatic function (creatinine less than or equal to 2.0 mg/dL, total bilirubin less than 2.0 mg/dL, aspartate aminotransferase [AST] or alanine aminotransferase [ALT] less than 3 times the upper limit of normal).
5. Life expectancy of at least 6 weeks.
6. If currently receiving 5 day decitabine regimen, patient must be scheduled to receive one more cycle of 5 day decitabine.
7. Recovered from all toxic effects of all prior therapy before entry into this study.
8. Women of childbearing potential and all men must agree to practice a medically approved form of contraception (one of the following must be used: condoms [male or female] with a spermicidal agent, diaphragm or cervical cap with a spermicidal agent, intrauterine device, hormonal contraception, abstinence) during the course of the study and up to 2 months following the last dose of decitabine.

Exclusion Criteria:

1. Candidates for up front high dose induction chemotherapy. MDS patients who are scheduled to receive decitabine prior to a bone marrow transplant or stem cell transplant are allowed.
2. History of treatment failure with decitabine.
3. Received any experimental agent within the preceding 30 days prior to screening.
4. Uncontrolled cardiac or pulmonary disease.
5. History of intestinal surgery, pancreatic surgery, or gastric surgery.
6. Any clinically relevant disease, disorder (including psychiatric disorders), or condition, in the opinion of the Investigator, which may interfere with the objectives of the study, especially with the gastrointestinal (GI) absorption of the study drug, and/or with the safety of the subject in the study.
7. Current active colitis of any etiology (Clostridium difficile colitis, ulcerative colitis, Crohn's disease, etc.) or a recent (less than 2 weeks) episode of colitis.
8. Pregnant or lactating. Female patients of childbearing potential must have had a negative serum pregnancy test at screening and a negative urine pregnancy test on Day 1 prior to dosing.
9. Known positive serology for human immunodeficiency virus (HIV).
10. Active viral, fungal, or bacterial infection. No patient may enter the study unless infections have been fully treated.