Imatinib Mesylate in Treating Patients With Myelofibrosis

DISEASE CHARACTERISTICS: * Diagnosis of myelofibrosis with myeloid metaplasia (MMM), defined by all of the following: * Leukoerythroblastic blood picture * Fibrosis involving \> 1/3 sectional area of bone marrow biopsy * Splenomegaly (unless patient has undergone prior splenectomy) * Philadelphia chromosome negative * No myelodysplastic syndrome * No systemic disorders associated with marrow fibrosis * Red blood cell transfusion dependent, defined by 1 of the following: * Patient has required ≥ 2 units of red blood cells every 4 weeks within the past 8 weeks * Hemoglobin ≤ 8 g/dL on ≥ 3 occasions (≥ 2 weeks apart ) over the past 8 weeks * No evidence of disease transformation to acute myelogenous leukemia, defined as \> 20% blasts in bone marrow and/or peripheral blood PATIENT CHARACTERISTICS: Performance status * ECOG 0-3 Life expectancy * Not specified Hematopoietic * Absolute neutrophil count \> 1,000/mm\^3 * Platelet count \> 50,000/mm\^3 Hepatic * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * AST or ALT ≤ 2 times ULN (unless due to extramedullary hematopoiesis in the liver) Renal * Creatinine ≤ 1.5 times ULN Cardiovascular * No New York Heart Association grade III-IV heart disease Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective barrier method contraception during and for 3 months after completion of study treatment * No serious, uncontrolled medical condition * No patients who are considered potentially unreliable or with a history of noncompliance to medical regimens PRIOR CONCURRENT THERAPY: Biologic therapy * More than 2 weeks since prior interferon alfa Chemotherapy * No concurrent chemotherapy except hydroxyurea to control elevated blood counts Endocrine therapy * More than 4 weeks since prior corticosteroids, danazol, or other androgens for MMM Other * More than 4 weeks since other prior treatment for MMM * No other concurrent experimental drug therapy for MMM