RATIONALE: Drugs used in chemotherapy use different ways to stop cancer cells from dividing so they stop growing or die.

PURPOSE: Phase I trial to study the effectiveness of dolastatin 10 in treating patients who have refractory or relapsed acute leukemia, chronic myelogenous leukemia in blast phase, or myelodysplastic syndrome.

OBJECTIVES: I. Determine the maximum tolerated dose and dose limiting toxicity of dolastatin 10 in patients with chronic myelogenous leukemia in blast phase, refractory or relapsed acute leukemia, or myelodysplastic syndromes. II. Assess the possible antileukemia effect of this treatment in these patients.

OUTLINE: This is a dose escalation study. Patients receive dolastatin 10 intravenous (IV) bolus once every 3 weeks. Patients receive 2-12 courses of therapy in the absence of disease progression and unacceptable toxicity. In the absence of dose limiting toxicity (DLT) in the first cohort of 3 patients, subsequent cohorts of 3 patients each receive escalating doses of dolastatin 10. If DLT occurs in 2 of 3 patients at a given dose level, then dose escalation ceases and the next lower dose is declared the maximum tolerated dose. Patients are followed until death.

PROJECTED ACCRUAL: This study will accrue up to 25 patients within 8 months.

DISEASE CHARACTERISTICS: Histologically diagnosed chronic myelogenous leukemia in blastic phase, refractory or relapsed acute leukemia, or myelodysplastic syndromes (refractory anemia with excess blasts (RAEB), RAEB in transformation, or chronic myelomonocytic leukemia)

PATIENT CHARACTERISTICS: Age: Not specified Performance status: 0-2 Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Bilirubin no greater than 1.5 mg/dL SGPT no greater than 2 times upper limit of normal Renal: Creatinine no greater than 1.5 mg/dL OR Creatinine clearance greater than 60 mL/min Other: Not pregnant or nursing Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: At least 4 weeks since prior chemotherapy and recovered (unless evidence of rapid disease progression) Endocrine therapy: Not specified Radiotherapy: Not specified Surgery: Not specified