Vismodegib and Gemcitabine Hydrochloride in Treating Patients With Advanced Pancreatic Cancer

PRIMARY OBJECTIVES: I. To obtain tumor biopsies before and after therapy with GDC-0449 (vismodegib) to evaluate the effect of inhibition of hedgehog signaling on pancreatic cancer stem cells by: evaluating the tumor for number and percentage of pancreatic cancer stem cells before and after treatment with GDC-0449. SECONDARY OBJECTIVES: I. To assess progression free survival (PFS) at 3 months following treatment with GDC-0449 and gemcitabine (gemcitabine hydrochloride). II. To assess response rate to treatment and overall survival in patients with advanced pancreas cancer treated with GDC-0449 alone and in combination with gemcitabine. III. To evaluate the toxicity of GDC-0449 alone and in combination with gemcitabine. OUTLINE: Patients receive vismodegib orally (PO) once daily (QD) on days 1-28 and gemcitabine hydrochloride intravenously (IV) over 30 minutes on days 1, 8, and 15 (beginning in course 2). Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up for 4 weeks.