Inclusion Criteria:

- Histologically or cytologically confirmed myeloid metaplasia with myelofibrosis
(MMM), including all of the following subtypes:

- Chronic idiopathic myelofibrosis

- Agnogenic myeloid metaplasia

- Post-thrombocythemic myelofibrosis

- Post-polycythemic myelofibrosis

- Diffuse bone marrow fibrosis

- Absence of Philadelphia chromosome OR BCR-ABL rearrangement in peripheral blood cells

- Meets 1 of the following criteria:

- Anemia (hemoglobin < 11 g/dL)

- Palpable splenomegaly*

- Morphologic evidence of advanced phase disease, including accelerated phase (10-19%
blasts), or evidence of evolution to acute leukemia (≥ 20% blasts) allowed

- No known CNS disease

- Performance status - ECOG 0-2

- Performance status - Karnofsky 60-100%

- No concurrent combination antiretroviral therapy for HIV-positive patients

- Bilirubin ≤ 2 mg/dL unless associated with hemolytic anemia as a result of
predominantly unconjugated hyperbilirubinemia

- AST and ALT ≤ 3 times upper limit of normal (unless due to disease)

- Creatinine ≤ 2 mg/dL

- No symptomatic congestive heart failure

- No unstable angina pectoris

- No cardiac arrhythmia

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No history of allergic reaction attributed to compounds of similar chemical or
biologic composition to decitabine

- No ongoing or active infection

- No other uncontrolled illness

- No psychiatric illness or social situation that would preclude study compliance

- At least 2 weeks since prior growth factors (e.g., epoetin alfa, filgrastim [G-CSF],
or sargramostim [GM-CSF])

- No concurrent prophylactic G-CSF or GM-CSF

- No concurrent epoetin alfa

- At least 4 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosoureas)

- No prior decitabine

- No other concurrent chemotherapy

- At least 4 weeks since prior androgenic steroids

- No concurrent androgenic steroids

- Prior splenic irradiation allowed

- At least 4 weeks since prior radiotherapy

- No concurrent radiotherapy

- Recovered from all prior therapy

- At least 4 weeks since other prior therapy

- No other concurrent investigational agents

- No other concurrent antineoplastic agents