Antithymocyte Globulin Compared With Supportive Care in Treating Patients With Myelodysplastic Syndrome

DISEASE CHARACTERISTICS:

Histologically or cytologically confirmed early myelodysplastic syndrome (MDS) with less than 10% bone marrow blasts

Refractory anemia (RA)
RA with excess blasts (RAEB)
Hypocellular myelodysplasia
Low or intermediate-1 prognostic risk

Transfusion-dependent

Need for 2 or more units of red blood cells or platelets per month for 2 or more months prior to study OR

History of prior transfusions and 2 consecutive (at least 21 days apart) hemoglobin levels less than 8.0 g/dL or platelet counts less than 20,000/mm^3 during the past 2 months

Hemoglobin no greater than 12.0 g/dL after prior transfusion
No myelosclerosis occupying more than 30% of bone marrow space
No RA with ringed sideroblasts, RAEB in transformation, or chronic myelomonocytic leukemia
No therapy-related MDS
No history of immune-related hematologic disorder (e.g., idiopathic thrombocytopenic purpura)

PATIENT CHARACTERISTICS:

Age:

18 and over

Performance status:

ECOG 0-2

Life expectancy:

At least 3 months

Hematopoietic:

See Disease Characteristics
No other causes of cytopenia unrelated to MDS (e.g., gastrointestinal blood loss)
Iron present on marrow examination OR
Transferrin saturation at least 20% and ferritin at least 50 ng/mL

Hepatic:

Bilirubin no greater than 2 mg/dL OR
SGOT/SGPT no greater than 2 times normal
No active or chronic hepatitis B or C

Renal:

Creatinine no greater than 2 mg/dL

Cardiovascular:

No symptomatic cardiac disease
No congestive heart failure (even if medically controlled)
No myocardial infarction within the past 6 months

Pulmonary:

No severe pulmonary disease
If history of pulmonary insufficiency, must have pO_2 at least 90 mm/Hg on room air or pCO_2 no greater than 40 mm/Hg

Other:

No history of unresolved B12 or folate deficiency since diagnosis of MDS
No untreated acute or chronic infection (afebrile for 7 days without antibiotics prior to study)
No active or chronic HIV
No concurrent cytomegalovirus infection
No other malignancy within the past 2 years except adequately treated localized squamous cell or basal cell skin cancer or carcinoma in situ of the cervix
No concurrent drug or alcohol abuse
No significant medical or psychosocial problems
No known allergy to rabbit protein
Not pregnant or nursing
Negative pregnancy test
Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

At least 8 weeks since prior biologic agents, colony-stimulating factors, or epoetin alfa for MDS
At least 8 weeks since other prior investigational biologic agents
No prior or concurrent bone marrow transplantation
No concurrent epoetin alfa
No concurrent growth factors except filgrastim (G-CSF) or sargramostim (GM-CSF) for neutropenic fevers
No other concurrent biologic agents

Chemotherapy:

At least 8 weeks since prior cytotoxic drugs for MDS
Concurrent chemotherapy for clinical indications of disease progression or leukemic transformation allowed

Endocrine therapy:

At least 8 weeks since prior androgenic hormonal therapy for MDS
At least 8 weeks since prior danazol for MDS

Radiotherapy:

No prior radiotherapy

Surgery:

No prior organ transplantation

Other:

At least 8 weeks since prior investigational drugs
At least 8 weeks since prior immunosuppressive drugs or other drugs for MDS
No concurrent immunosuppressive therapy
No other concurrent experimental drugs