DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed hematologic malignancy of 1 of the following types:

  • Acute myeloid leukemia, except acute promyelocytic leukemia
  • Acute lymphoblastic leukemia
  • Chronic myelogenous leukemia in blast crisis
• Refractory or relapsed disease after most recent therapy AND considered ineligible for potential curative therapy, including allogeneic stem cell transplantation
• Multilineage bone marrow failure due to leukemia allowed

• Total peripheral blood blast count < 30,000/mm^3

  • No rapidly increasing peripheral blood blast counts (i.e., increase in absolute blast count > 50% within 1 week) OR uncontrolled peripheral blood blast counts (i.e., absolute blast count > 30,000/mm^3) despite hydroxyurea treatment
• No active and/or untreated CNS leukemia

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2 OR
• Karnofsky 60-100%

Life expectancy

• More than 2 months

Hematopoietic

• See Disease Characteristics
• No bleeding diathesis

Hepatic

• Bilirubin ≤ 2 mg/dL
• AST and ALT ≤ 5 times upper limit of normal (ULN)

Renal

• Creatinine normal OR
• Creatinine clearance ≥ 60 mL/min

Cardiovascular

• No uncontrolled hypertension (i.e., persistent grade 3 hypertension despite treatment)
• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No ongoing or active infection
• No history of allergic reactions attributed to compounds of similar chemical or biological composition to the study drug
• No psychiatric illness or social situation that would preclude study compliance
• No other uncontrolled illness

PRIOR CONCURRENT THERAPY:

Biologic therapy

• At least 3 weeks since prior biologic therapy, including myeloid growth factors

Chemotherapy

• See Disease Characteristics
• At least 3 weeks since prior cytotoxic chemotherapy, except hydroxyurea
• Prior hydroxyurea used to control blast counts allowed provided it is discontinued within 48 hours of the initiation of the study drug

Endocrine therapy

• Not specified

Radiotherapy

• At least 2 weeks since prior radiotherapy

Surgery

• Not specified

Other

• Recovered from all prior therapy
• No other concurrent investigational agents
• No other concurrent anticancer therapy
• No concurrent combination antiretroviral therapy for HIV-positive patients

• No concurrent therapeutic anticoagulation

  • Concurrent prophylactic anticoagulation (i.e., low-dose warfarin) for venous or arterial access devices allowed provided requirements for PT, INR, or PTT are met

• No concurrent cytochrome P450 enzyme-inducing antiepileptic drugs, including any of the following:

  • Phenytoin
  • Carbamazepine
  • Phenobarbital
• No concurrent rifampin
• No concurrent Hypericum perforatum (St. John's wort)