Sorafenib and Gemcitabine in Treating Patients With Locally Advanced or Metastatic Pancreatic Cancer

Inclusion Criteria: * Histologically or cytologically confirmed adenocarcinoma of the pancreas * Locally advanced or metastatic disease * Locally advanced disease must extend outside the boundaries of a standard radiotherapy port * Not amenable to curative surgery or radiotherapy * Measurable disease * At least 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques OR ≥ 10 mm by spiral CT scan * Pleural effusion and ascites are not considered measurable lesions * Outside prior radiotherapy port * No known brain metastases * Performance status - ECOG 0-1 * Performance status - Karnofsky 70-100% * More than 3 months * WBC ≥ 3,000/mm\^3 * Absolute neutrophil count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 * No evidence of bleeding diathesis * Bilirubin normal * AST and/or ALT ≤ 2.5 times upper limit of normal * Creatinine normal * Creatinine clearance ≥ 60 mL/min * No uncontrolled hypertension * No symptomatic congestive heart failure * No unstable angina pectoris * No cardiac arrhythmia * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No active or ongoing infection * No other active malignancy * No history of allergic reaction attributed to compounds of similar chemical or biological composition to sorafenib or other study agents * No psychiatric illness or social situation that would preclude study compliance * No other uncontrolled illness * No prior antiangiogenic agents * No prior cytotoxic chemotherapy for metastatic disease * At least 4 weeks since prior adjuvant chemotherapy (6 weeks for nitrosoureas or mitomycin) and recovered * No prior gemcitabine * See Disease Characteristics * At least 4 weeks since prior radiotherapy and recovered * No prior investigational drugs * No prior sorafenib * No prior MAPK signaling agents * Concurrent warfarin anticoagulation allowed provided the following criteria are met: * Therapeutic on a stable warfarin dose * INR ≤ 3 * Undergo weekly INR testing * No active bleeding or pathological condition that carries a high risk of bleeding * No concurrent combination antiretroviral therapy for HIV-positive patients * No other concurrent investigational agents * No other concurrent anticancer therapies