DISEASE CHARACTERISTICS:

• Histologically confirmed gastrointestinal stromal tumor (GIST)

  • Metastatic or unresectable disease

    • Determined to be unresectable for cure
• Measurable and/or nonmeasurable disease by MRI or CT scan
• No known brain metastasis

PATIENT CHARACTERISTICS:

• Zubrod performance status 0-3
• Platelet count ≥ 100,000/mm^3
• Absolute neutrophil count ≥ 1,000/mm^3
• Hemoglobin ≥ 9 g/dL (transfusion allowed)
• Bilirubin ≤ 2.0 times upper limit of normal (ULN)
• SGOT/SGPT ≤ 2.5 times ULN (5 times ULN with liver involvement)
• Creatinine ≤ 1.5 times ULN
• Urine protein:creatinine ratio < 1
• INR ≤ 1.5
• PTT normal
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective barrier contraception during and for up to 6 months after completion of study treatment
• No cerebrovascular accident, transient ischemic attack, myocardial infarction, or unstable angina within the past 6 months
• No serious cardiac arrhythmia requiring medication
• No New York Heart Association class II-IV congestive heart failure
• No clinically significant peripheral vascular disease
• No abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess within the past 28 days

• No contraindication to oral medications (e.g., severe dysphagia)

  • G- or J-tubes allowed
• No history of hypertension unless well controlled (i.e., blood pressure < 160/90 mm Hg) and on a stable regimen of antihypertensive therapy
• No serious nonhealing wound, ulcer, or bone fracture

• No other prior malignancy except for any of the following:

  • Adequately treated basal cell or squamous cell skin cancer
  • In situ cervical cancer
  • Adequately treated stage I or II cancer that is currently in complete remission
  • Any other cancer for which the patient has been disease free for ≥ 5 years
• No significant traumatic injury in the past 28 days

PRIOR CONCURRENT THERAPY:

• Recovered from prior therapy
• At least 28 days since prior chemotherapy

• At least 28 days since prior radiotherapy

  • Evidence of progressive disease within the radiation field or disease outside the radiation field

• No prior bevacizumab or other agents targeting vascular endothelial growth factor (VEGF), VEGF receptor, or platelet-derived growth factor receptor (PDGFR) for advanced disease

  • These agents may have been used in the adjuvant setting provided no recurrence for ≥ 12 months after completion of therapy
• More than 28 days since prior major surgery or open biopsy
• No anticipated need for major surgery
• More than 7 days since prior fine-needle aspiration or core biopsies
• More than 7 days since prior procedure to place a portacath
• No other concurrent anticancer biologic agents, chemotherapy, radiotherapy, or any other anticancer agents

• No concurrent therapeutic warfarin for anticoagulation

  • Concurrent low-molecular weight heparin or other agents for therapeutic anticoagulation or mini-dose warfarin for prophylaxis allowed
• No other concurrent investigational agents