Gemcitabine and Imatinib Mesylate as First-Line Therapy in Patients With Locally Adv. or Metastatic Pancreatic Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed pancreatic adenocarcinoma or poorly differentiated carcinoma (originating in the pancreas) Locally advanced or metastatic disease Not eligible for curative resection Must have measurable or evaluable disease as defined by RECIST criteria No CA19-9 elevation as only evidence of disease No known brain metastases PATIENT CHARACTERISTICS: ECOG performance status 0-2 Absolute neutrophil count ≥ 1,500/mm³ Platelet count ≥ 125,000/mm³ Bilirubin < 1.5 times upper limit of normal (ULN) AST and ALT ≤ 2.5 times ULN Alkaline phosphatase < 3 times ULN Creatinine ≤ 1.5 times ULN OR creatinine clearance ≥ 60 mL/min Not pregnant or nursing Negative pregnancy test Fertile patients must use effective nonhormonal contraception No coexisting medical condition that would preclude study compliance No inability to ingest tablets No active illness (e.g., active or uncontrolled infection, uncontrolled cardiac disease) that would preclude study participation No chronic uncontrolled diarrhea and/or daily emesis No other cancer within the past 5 years except for surgically removed noninvasive nonmelanoma skin cancer or in situ cervical cancer PRIOR CONCURRENT THERAPY: No prior chemotherapy for metastatic disease No prior gemcitabine No prior imatinib mesylate Prior surgical resection and adjuvant fluorouracil chemotherapy allowed provided there was an interval of > 6 months between the last dose of adjuvant chemotherapy and recurrence of pancreatic cancer Prior fluorouracil as a radiosensitizing agent allowed At least 4 weeks since prior radiotherapy and recovered Must have evidence of disease outside the radiation fields OR radiologically confirmed disease progression within the radiation fields after completion of radiotherapy No concurrent therapeutic warfarin Prophylactic warfarin ≤ 1 mg daily allowed for prophylaxis of central venous catheter thrombosis Low molecular weight heparin or heparin allowed for anticoagulation No concurrent chronic systemic corticosteroids No other concurrent agents or therapies, including chemotherapy, immunotherapy, hormonal cancer therapy, radiotherapy, or cancer surgery No other concurrent experimental medications No concurrent filgrastim (G-CSF) or sargramostim (GM-CSF)