DISEASE CHARACTERISTICS:

• Histologically confirmed gastrointestinal stromal tumor

  • Advanced disease, defined as unresectable mestastatic or primary disease
• Kit-expressing tumor

• Limited* or generalized** disease progression after adequate therapy with imatinib mesylate (≥ 400 mg/day for at least 6 weeks), as defined by both of the following:

  • Increase in unidimensional tumor size of ≥ 10% AND did not meet criteria for partial response by CT scan density
  • Any new lesions, including new tumor nodules in a previous cystic tumor NOTE: *Some, but not all, tumor foci progressing AND not amenable to local therapy

NOTE: **Widespread progression of all tumor foci

• Measurable disease by CT scan

  • If a targeted lesion has been previously embolized or irradiated, there must be objective evidence of disease progression

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2

Life expectancy

• Not specified

Hematopoietic

• Absolute neutrophil count ≥ 1,000/mm^3
• Platelet count ≥ 100,000/mm^3

Hepatic

• SGOT or SGPT ≤ 2.5 times upper limit of normal (ULN) (5 times ULN if liver metastases are present)
• PT and PTT ≤ 1.5 times ULN
• Bilirubin ≤ 1.5 times ULN
• No uncontrolled chronic liver disease

Renal

• Creatinine ≤ 1.5 times ULN
• No uncontrolled chronic renal disease

Cardiovascular

• No New York Heart Association class III or IV cardiac disease
• No congestive heart failure
• No acute myocardial infarction within the past 2 months

Other

• Intellectually, emotionally, and physically able to maintain an ambulatory infusion pump
• No uncontrolled diabetes
• No uncontrolled seizure disorder
• No active uncontrolled infection
• HIV negative
• No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix
• No other concurrent significant medical disease
• 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

PRIOR CONCURRENT THERAPY:

Biologic therapy

• At least 4 weeks since prior biologic therapy

Chemotherapy

• At least 4 weeks since prior chemotherapy

Endocrine therapy

• Not specified

Radiotherapy

• See Disease Characteristics
• At least 4 weeks since prior radiotherapy and recovered

Surgery

• No prior organ allografts

Other

• Recovered from all prior therapy such that severity is ≤ grade 1 for nonhematological toxicities except nausea and vomiting controlled with standard anti-emetic regimens, alopecia, fatigue, and peripheral edema
• At least 4 weeks since prior embolization
• At least 4 weeks since prior imatinib mesylate
• At least 4 weeks since other prior therapy

• No concurrent warfarin

  • Low-dose warfarin or low molecular weight heparin allowed for prophylaxis