MS-275 and Azacitidine in Treating Patients With Myelodysplastic Syndromes, Chronic Myelomonocytic Leukemia, or Acute Myeloid Leukemia

Inclusion Criteria:

* Diagnosis of 1 of the following:

  * Histologically confirmed myelodysplastic syndromes (MDS) by bone marrow aspiration and/or biopsy
  * International Prognostic Scoring System (IPSS) score of intermediate-1, intermediate-2, or high
  * International Prognostic Scoring System (IPSS) score of intermediate-1, intermediate-2, or high
  * Low IPSS score allowed provided patient has a clinically significant cytopenia (i.e., absolute neutrophil count \< 1,000/mm\^3, untransfused hemoglobin \< 8 g/dL, platelet count \< 20,000/mm\^3, or anemia requiring transfusion)
  * Chronic myelomonocytic leukemia
  * Acute myeloid leukemia (AML)
  * Relapsed or refractory disease
* Untreated AML allowed provided patient meets \>= 1 of the following criteria:

  * Age 60 and over
  * AML arising in the setting of an antecedent hematologic disorder
  * High-risk cytogenetic abnormalities
  * Medical conditions that may compromise the ability to give cytotoxic chemotherapy as the primary modality
  * Refused cytotoxic chemotherapy
* WBC \< 30,000/mm3 for \>= 2 weeks before study entry
* Acute promyelocytic leukemia allowed provided patient is in at least second relapse and has already received treatment regimens containing arsenic trioxide and isotretinoin
* No clinical evidence of CNS or pulmonary leukostasis or CNS leukemia
* Peformance status:

  * Zubrod 0-2
* Life expectancy:

  * At least 6 months
* Hematopoietic:

  * See Disease Characteristics

    * Hemoglobin ≥ 8 g/dL (transfusion allowed)
    * No disseminated intravascular coagulation
* Renal:

  * Creatinine normal OR
  * Creatinine clearance \>= 60 mL/min
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception during and for 3 months after study treatment
* No untreated, active infection
* No other serious or uncontrolled medical condition
* More than 3 weeks since prior hematopoietic growth factors for this malignancy
* At least 3 weeks since prior hydroxyurea (2 weeks for AML patients)
* No concurrent hydroxyurea
* Recovered from all prior therapy
* At least 2 weeks since prior cytotoxic therapy (AML patients)
* More than 3 weeks since other prior therapy for this malignancy
* No other concurrent investigational or commercial agents or therapies for this malignancy
* No concurrent valproic acid
* Hepatic:

  * Bilirubin normal unless due to hemolysis or Gilbert's syndrome
  * AST and ALT =\< 2.5 times upper limit of normal