This randomized phase II is studying how well giving sorafenib with or without gemcitabine works in treating patients with metastatic pancreatic cancer. Sorafenib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth and by blocking blood flow to the tumor. Drugs used in chemotherapy, such as gemcitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving sorafenib together with gemcitabine may kill more tumor cells.

PRIMARY OBJECTIVES:

I. To determine the objective response rate in patients with metastatic pancreatic cancer treated with concurrent gemcitabine and BAY43-9006 and sequential BAY 43-9006 followed by gemcitabine/BAY 43-9006 at progression.

SECONDARY OBJECTIVES:

I. To determine the six month overall survival rate, 3 month progression free survival rate, time to tumor progression and overall survival of patients with metastatic pancreatic cancer treated with concurrent gemcitabine and BAY43-9006 and sequential BAY 43-9006 followed by gemcitabine/BAY 43-9006 at progression.

II. To determine the safety profile of gemcitabine and BAY43-9006 in patients with metastatic pancreatic cancer and compared to those treated with single agent BAY 43-9006.

III. To determine whether mRNA expression levels of genes involved in the gemcitabine pathway (RR, dck, dcd) and genes involved in the Raf pathway (cyclin D, VEGFR2, p21) will predict for time to progression, overall survival, and response, in patients with metastatic pancreatic cancer treated with concurrent gemcitabine and BAY43-9006 and sequential BAY 43-9006 followed by gemcitabine/BAY 43-9006 at progression.

IV. To determine whether genomic polymorphisms of genes (measured in peripheral blood mononuclear cells) involved in the gemcitabine pathway (RR) and genes involved in the ras pathway (VEGFR2, cyclin D, p21) will predict for time to progression, overall survival, tumor response, and toxicity in patients with advanced cancer of the pancreas treated with concurrent gemcitabine and BAY43-9006 and sequential BAY 43-9006 followed by gemcitabine/BAY 43-9006 at progression.

OUTLINE: This is a randomized, multicenter study. Patients are randomized to 1 of 2 treatment arms.

ARM I: Patients receive oral sorafenib twice daily on days 1-28. Patients experiencing disease progression cross over to Arm II.

ARM II: Patients receive oral sorafenib as in Arm I and gemcitabine IV over 100 minutes on days 1, 8, and 15.

In both arms, courses repeat every 28 days in the absence of disease progression or unacceptable toxicity.

After completion of study treatment, patients are followed periodically.

Inclusion Criteria:

• Patients must have histologically or cytologically confirmed metastatic pancreatic carcinoma
• Patients must have measurable disease, defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded) as >= 20 mm with conventional techniques or as >= 10 mm with spiral CT scan
• No prior chemotherapy for metastatic disease is allowed; prior adjuvant chemotherapy is allowed provided that patients did not receive gemcitabine and the chemotherapy completed > 6 months prior to initiation of study therapy
• Available tumor biopsy specimen (paraffin embedded or fresh frozen) that was obtained at the time of diagnosis and/or prior to study entry is required
• Life expectancy of greater than 3 months
• ECOG performance status =< 1
• Leukocytes >= 3,000/μL
• Absolute neutrophil count >= 1,500/μL
• Platelets >= 100,000/μL
• Hemoglobin >= 9 mg/dL
• Total bilirubin =< 1.5 X institutional upper limit of normal
• AST(SGOT)/ALT(SGPT) =< 3 X institutional upper limit of normal, unless the liver is involved with tumor, in which the AST (SGOT)/ALT (SGPT) must be =< 5 X institutional upper limit of normal
• Creatinine =< 1.5 X institutional upper limit of normal OR creatinine clearance >= 60 mL/min/1.73 m^2
• The effects of BAY 43-9006 on the developing human fetus at the recommended therapeutic dose are unknown; for this reason and because raf kinase inhibitor agents as well as other therapeutic agents used in this trial are known to be teratogenic, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation; should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately
• Ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria:

• Because BAY 43-9006 is at least partially metabolized by the CYP 3A enzyme in the liver, the possible effect that inhibitors of CYP 3A may have on BAY 43-9006 is unknown; therefore, patients taking inhibitors of CYP 3A (such as ketoconazole, itraconazole, and ritonavir) may not be enrolled in this study
• Patients may not be receiving any other investigational agents
• Patients with known brain metastases should be excluded from this clinical trial because of their poor prognosis and because they often develop progressive neurologic dysfunction that would confound the evaluation of neurologic and other adverse events
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to BAY 43-9006 or gemcitabine
• Secondary primary malignancy (except in situ carcinoma of the cervix, in situ cancer of the prostate, in situ cancer of the breast or adequately treated nonmelanomatous carcinoma of the skin or other malignancy treated at least 5 years previously with no evidence of recurrence); concurrent or history of another malignancy =< 5 years
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, uncontrolled hypertension, or psychiatric illness/social situations that would limit compliance with study requirements
• Pregnant women are excluded from this study because BAY 43-9006 is a kinase inhibitor agent with the potential for teratogenic or abortifacient effects; because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with BAY 43-9006, breastfeeding should be discontinued if the mother is treated with BAY 43-9006
• Patients with immune deficiency are at increased risk of lethal infections when treated with marrow-suppressive therapy; therefore, HIV-positive patients receiving combination anti-retroviral therapy are excluded from the study because of possible pharmacokinetic interactions with BAY 43-9006; appropriate studies will be undertaken in patients receiving combination anti-retroviral therapy when indicated
• Patients with evidence of bleeding diathesis
• Patients receiving therapeutic doses of anticoagulation; prophylactic anticoagulation (i.e. low dose warfarin) of venous or arterial access devices is allowed

Adverse Events occured over a 36 month period.

"Other Adverse Events" include all events that were not severe adverse events regardless of grade or relation to treatment.