DISEASE CHARACTERISTICS:

• Diagnosis of myelodysplastic syndromes (MDS), including the following subtypes:

  • Refractory anemia (RA)
  • RA with ringed sideroblasts (RARS)
  • Refractory cytopenia with multilineage dysplasia (RCMD)
  • RCMD and ringed sideroblasts (RCMD-RS)
  • RA with excess blasts (RAEB-1, < 5% blasts)

• Meets 1 of the following hematologic parameters:

  • Anemia requiring transfusion support with ≥ 1 unit of packed red blood cells per month for ≥ 2 months accompanied with ≥ 1 of the following laboratory values:

    • Anemia, defined as hemoglobin < 9 g/dL OR reticulocyte count < 60,000/mm^3
    • Thrombocytopenia, defined as platelet count < 50,000/mm^3
    • Neutropenia, defined as absolute neutrophil count < 500/mm^3

• Disease status must meet 1 of the following criteria:

  • No suitable sibling marrow donor match
  • Suitable sibling marrow match available, but patient refuses transplantation
  • Prior response to horse-antithymocyte globulin (h-ATG) or h-ATG with cyclosporine
• No chronic myelomonocytic leukemia, RAEB-2 (5-19% blasts), or secondary MDS
• Not refractory to prior ATG or ATG with cyclosporine
• No transformation to acute leukemia (RAEB-T, > 20% blasts in marrow)
• High or intermediate probability of response predicted

PATIENT CHARACTERISTICS:

Age

• 18 to 72

Performance status

• Not specified

Life expectancy

• At least 6 months

Hematopoietic

• See Disease Characteristics

Hepatic

• No concurrent severe hepatic disease that would preclude study treatment

Renal

• No concurrent severe renal disease that would preclude study treatment

Cardiovascular

• No concurrent severe cardiac disease that would preclude study treatment

Pulmonary

• No concurrent severe pulmonary disease that would preclude study treatment

Other

• Not pregnant
• No nursing during and for 3 months after the completion of study treatment
• Negative pregnancy test
• Fertile patients must use effective contraception during and for ≥ 6 months after completion of study treatment
• HIV negative
• No active infection
• No other malignancy except nonmelanoma skin cancer
• No prior hypersensitivity to study drugs or its components
• No concurrent severe neurologic, infectious, or metabolic disease that would preclude study treatment
• No moribund status
• No contact with anyone receiving oral polio vaccine

PRIOR CONCURRENT THERAPY:

Biologic therapy

• See Disease Characteristics
• At least 4 weeks since prior biologic therapy
• Prior or concurrent filgrastim (G-CSF)*, epoetin alfa, or transfusion support allowed
• No vaccine therapy during and for ≥ 1 year after completion of study treatment NOTE: *G-CSF can be used before, during, and after study treatment for patients with documented neutropenia < 500/mm3 as long as they meet the criteria for anemia and/or thrombocytopenia

Chemotherapy

• At least 4 weeks since prior chemotherapy
• No prior combination chemotherapy

Endocrine therapy

• At least 4 weeks since prior hormonal therapy

Radiotherapy

• At least 4 weeks since prior radiotherapy

Surgery

• Not specified

Other

• At least 2 weeks since prior herbal supplements (e.g., Echinacea purpurea or Usnea barbata [Old Man's Beard])
• No concurrent herbal supplements