Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed diagnosis of 1 of the following:

- Acute myelogenous leukemia (AML), meeting the following criteria:

- In first relapse after first treatment-induced complete remission (CR)
(closed to accrual as of 06/09/05)

- Duration of first CR less than 12 months

- No prior treatment for first relapse except hydroxyurea

- FAB type M0, M1, M2, M4-7

- No acute promyelocytic leukemia

- No prior treatment with a standard induction regimen containing cytotoxic
agents* (for patients 60 years of age or older)

- High-risk myelodysplasia, meeting the following criteria:

- 60 years of age and over

- No prior cytotoxic chemotherapy* except hydroxyurea

- Prior gemtuzumab ozogamicin allowed

- High risk defined as International Prognostic Scoring System score ≥ 1.5,
defined by cytogenetics, % marrow blasts, and lineage cytopenias NOTE:
*Prior low-dose, single-agent cytarabine, decitabine, or azacitidine not
considered prior cytotoxic chemotherapy

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- ECOG 0-2

Life expectancy

- Not specified

Hematopoietic

- Not specified

Hepatic

- Bilirubin ≤ 2.0 mg/dL

- ALT or AST ≤ 5 times upper limit of normal

- Chronic hepatitis allowed

Renal

- Creatinine ≤ 2.0 mg/dL

Cardiovascular

- No myocardial infarction within the past 3 months

- No symptomatic coronary artery disease

- No uncontrolled arrhythmias

- No uncontrolled congestive heart failure

- No other active heart disease

Other

- No uncontrolled active infection

- Not pregnant or nursing

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy

- Up to 4 leukapheresis procedures allowed during the first 15 days of study treatment

Chemotherapy

- See Disease Characteristics

- Concurrent additional hydroxyurea (maximum dose of 5 g daily for up to 4 days)
allowed between days 4 and 15 of each study course to control elevated blast levels

Endocrine therapy

- Not specified

Radiotherapy

- Not specified

Surgery

- Not specified

Other

- Recovered from all prior therapy

- At least 72 hours since prior anti-leukemic treatment with a non-cytotoxic agent

- No concurrent disulfiram (Antabuse)

- No other concurrent anticancer drugs except anagrelide within the first 15 days of
study treatment to control elevated platelet counts

- No other concurrent treatment for leukemia, except hydroxyurea used during study
treatment

- No other concurrent investigational drugs