DISEASE CHARACTERISTICS: Histologically, morphologically, or cell surface marker confirmed adult acute myeloid leukemia (AML) Recurrent or refractory after at least 1 prior induction therapy OR Relapsed after remission of less than 1 year duration Antecedent myelodysplasia that has evolved to AML allowed Ineligible for allogeneic stem cell transplantation or failed prior transplantation No CNS leukemia

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Zubrod 0-2 Life expectancy: At least 12 weeks Hematopoietic: WBC no greater than 10,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL Transaminases less than 5 times upper limit of normal Albumin at least 3 g/dL Renal: Creatinine no greater than 1.5 mg/dL Cardiovascular: Cardiac ejection fraction at least 50% normal No myocardial infarction within the past 6 months No disseminated intravascular coagulation Pulmonary: FEV1 at least 70% normal Other: No uncontrolled infections No other concurrent serious medical problems or psychiatric disorders No prior severe penicillin allergy (hives or anaphylactic reactions) Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics No concurrent growth factors Chemotherapy: See Disease Characteristics Recovered from prior chemotherapy Prior hydroxyurea or low-dose cytarabine (less than 100 mg subcutaneously) to lower blast counts allowed if discontinued on day 1 of study therapy No concurrent antineoplastic chemotherapy Endocrine therapy: Concurrent corticosteroids allowed, including antiemetics Radiotherapy: Recovered from prior radiotherapy No concurrent radiotherapy Surgery: Not specified