A Phase III Randomized Study of Imatinib, with or without Bevacizumab (NSC-704865), in Patients with Metastatic or Unresectable Gastrointestinal Stromal Tumors

Biopsy-proven diagnosis of GIST that is distantly metastatic or unresectable. CT or MRI for any measurable dz within 28 days prior to reg. CT or MRI for non-measurable dz within 42 days prior to reg. Scans must be submitted for central review. Archived tissue must be submitted. Must seek additional consent for submission of PET scans. No known brain mets. Zubrod 0-3. At least 18 years of age. Must have resolution of transient toxicities from any prior chemo, RT or surgery to </= Grade 1. May have received traditional chemo agents in any setting, provided at least 28 days have elapsed and patient has recovered from toxicities. No prior therapy with bevacizumab or other agents targeting VEGF, VEGFR, or PDGFR is allowed for advanced disease. Those agents may have been used in the adjuvant setting if patient did not recur for at least 12 months following completion of therapy. Pts may be receiving imatinib prior to registration if they have not received more than 30 days of imatinib, they have not been restaged, and they have no clinical signs of progression. Prior RT is allowed provided at least 28 days have elapsed and there is evidence of progressive disease within the radiation field or disease outside the radiation field. Must not have had a major surgical procedure, open biopsy, or significant traumatic injury within 28 days prior to reg, or anticipation of need for major surgical procedure during the course of the study. No FNA or core biopsies within 7 days prior to reg. No procedure to place a portacath is allowed within 7 days prior to reg. Within 28 days prior to reg: total bilirubin </= 2.0 x IULN; SGOT or SGPT </= 2.5 x IULN (</= 5 x IULN for patients with liver involvement); serum creatinine </= 1.5 x IULN; UPC ratio </= 1; ANC >/= 1,000/mcl; platelets >/= 100,000/mcl; hemoglobin >/= 9 gm/dl; INR </= 1.5; PTT </= IULN. Must not be taking therapeutic doses of coumadin as anticoagulation. Patients requiring therapeutic anticoagulation may use low-molecular weight heparin or other agents, and mini-dose coumadin as prophylaxis is allowed. Must not have had a CVA, TIA, myocardial infarction or unstable angina within 6 months prior to reg. Must not have serious cardiac arrhythmia requiring medication, NYHA Class II or greater congestive heart failure, or clinically significant peripheral vascular disease. Must not have had an abdominal fistula, GI perforation or intra-abdominal abscess within 28 days prior to reg. Must not plan to use other investigational agents while on protocol treatment. Must have no contra-indication to oral medications (patients with G- or J- tubes are eligible). Must not have blood pressure > 160/90. Pts with hx of hypertension must be on a stable regimen of anti-hypertensive therapy. Must not have serious, non-healing wound, ulcer, or bone fracture.