Bevacizumab and Gemcitabine in Treating Patients With Advanced Pancreatic Cancer

Inclusion Criteria: * Histologically or cytologically confirmed pancreatic adenocarcinoma * Not amenable to curative treatment with surgery or radiotherapy * Locally advanced disease must extend outside the boundaries of a standard radiation port * At least 1 unidimensionally measurable lesion * At least 20 mm by conventional techniques OR at least 10 mm by spiral CT scan * Pleural effusions and ascites not considered measurable lesions * No obvious tumor involvement of major vessels on CT scan * No known brain metastases * Performance status - ECOG 0-2 * More than 3 months * WBC at least 3,000/mm\^3 * Absolute neutrophil count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 * No prior bleeding diathesis * Bilirubin normal * AST/ALT no greater than 2.5 times upper limit of normal * PT INR no greater than 1.5 * Creatinine no greater than 1.5 mg/dL * Creatinine clearance at least 60 mL/min * Urine protein less than 500 mg/24 hours if at least 1+ proteinuria * No significant renal impairment * No prior cardiovascular accident * No prior deep vein thrombosis * No myocardial ischemia or infarction within the past 6 months * No uncompensated coronary artery disease within the past 6 months * No uncontrolled hypertension * No symptomatic congestive heart failure * No cardiac arrhythmia * No clinically significant peripheral artery disease * No arterial thromboembolic event within the past 6 months, including any of the following: * Transient ischemic attack * Cerebrovascular accident * Unstable angina * Myocardial infarction * No prior pulmonary embolism * No concurrent uncontrolled illness * No ongoing or active infection * No other concurrent active malignancy within the past 5 years except nonmelanoma skin cancer or carcinoma in situ of the cervix * No psychiatric illness or social situation that would preclude study entry * No prior allergic reaction attributed to compounds of similar chemical or biologic composition to bevacizumab or other agents (Chinese hamster ovary cell products or other recombinant human antibodies) used in this study * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No prior bevacizumab * No prior cytotoxic chemotherapy for metastatic disease * No prior gemcitabine * At least 4 weeks since prior adjuvant chemotherapy and recovered * At least 4 weeks since prior radiotherapy and recovered * No prior radiotherapy to sole site of measurable disease * At least 6 weeks since prior major surgery * At least 30 days since prior investigational agents * At least 1 month since prior and no concurrent thrombolytic agents or full-dose anticoagulants (except to maintain patency of pre-existing permanent indwelling IV catheters) * No concurrent chronic daily aspirin (more than 325 mg/day) or nonsteroidal anti-inflammatory drugs known to inhibit platelet function * No other concurrent investigational agents * No concurrent combination antiretroviral therapy for HIV-positive patients * No other concurrent anticancer therapy