RATIONALE: STI571 may interfere with the growth of cancer cells and may be an effective treatment for soft tissue sarcoma.

PURPOSE: Phase I/II trial to study the effectiveness of STI571 in treating patients who have recurrent or refractory soft tissue sarcoma.

OBJECTIVES: I. Determine the maximum tolerated dose and associated toxicity of STI571 in patients with refractory or recurrent soft tissue sarcoma. II. Determine the pharmacokinetic profile of this treatment regimen in these patients. III. Determine the objective response and duration of response in these patients with this treatment regimen.

OUTLINE: This is a dose escalation and dose efficacy, multicenter study. In the dose efficacy portion, patients are stratified according to disease type (gastrointestinal stromal tumor vs all other soft tissue sarcomas). Phase I: Patients receive oral STI571 daily for a maximum of 24 months in the absence of disease progression or unacceptable toxicity. Cohorts of 3-8 patients receive escalating doses of STI571 until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose at which 2 of 6-8 patients experience dose limiting toxicities. The recommended phase II dose is defined as the dose preceding the MTD. Phase II: Patients receive the recommended phase II dose of STI571 as in phase I. Patients are followed every 8 weeks until disease progression, and then every 16 weeks thereafter.

PROJECTED ACCRUAL: Approximately 47-72 patients (7-32 in phase I and 40 in phase II) will be accrued for this study.

DISEASE CHARACTERISTICS: Histologically confirmed soft tissue sarcoma Malignant fibrous histiocytoma Liposarcoma Rhabdomyosarcoma Synovial sarcoma Malignant paraganglioma Fibrosarcoma Leiomyosarcoma Angiosarcoma Hemangiopericytoma Neurogenic sarcoma Unclassified sarcoma Miscellaneous sarcoma (including mixed mesodermal tumors of the uterus) Gastrointestinal stromal tumor (GIST) (must be c-kit positive) No malignant mesothelioma, chondrosarcoma, neuroblastoma, osteosarcoma, Ewing's sarcoma, or embryonal rhabdomyosarcoma Phase I study and nonGIST phase II study patients: Must have received one prior first line combination chemotherapy regimen or two first line single agent regimens Adjuvant chemotherapy not considered first line, unless disease progression within 6 months of treatment Phase II GIST patients: No more than one prior first line combination chemotherapy regimen or two first line single agent regimens Adjuvant chemotherapy not considered first line, unless disease progression within 6 months of treatment Measurable disease with evidence of progression in past 6 weeks Osseous lesions and pleural effusions not considered measurable No symptomatic or known CNS metastases

PATIENT CHARACTERISTICS: Age: 15 and over Performance status: WHO 0-1 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.8 mg/dL Albumin at least 25 g/L Renal: Creatinine no greater than 1.4 mg/dL OR Creatinine clearance greater than 65 mL/min Cardiovascular: No history of cardiovascular disease Other: No prior or concurrent second primary malignant tumors except adequately treated carcinoma in situ of the cervix or basal cell carcinoma No other severe illness (including psychosis) Not pregnant Fertile patients must use effective contraception during and for 6 months following study

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy No other concurrent local or systemic chemotherapy Endocrine therapy: No concurrent systemic corticosteroid therapy Radiotherapy: No prior radiotherapy to sole index lesion Concurrent radiotherapy to any lesion allowed if not the sole target lesion Surgery: Not specified Other: No prior embolization to sole index lesion No other concurrent investigational drug No concurrent warfarin