Gemcitabine Hydrochloride With or Without Vismodegib in Treating Patients With Recurrent or Metastatic Pancreatic Cancer

Inclusion Criteria

• Patients must have histologically or cytologically confirmed adenocarcinoma of the pancreas
• 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 computed tomography (CT) scan
• Patients must have either:
• Newly diagnosed chemo-naïve metastatic pancreatic cancer; only patients who have not received any chemotherapy for their metastatic disease are eligible
• Recurrent disease after curative-intent surgery which has now recurred and is metastatic; patients who have recurrent disease may have received adjuvant chemotherapy or adjuvant chemoradiation, but may not have received any chemotherapy for metastatic disease; adjuvant therapy must have been completed >= 6 months prior to the diagnosis of recurrent disease, or if not adjuvant therapy received, surgery must have been performed >= 6 months prior to the diagnosis of recurrent disease
• Age >= 21 years
• Life expectancy > 3 months
• Karnofsky performance status >= 80%
• Granulocytes >= 1,500/mcL
• Platelet count >= 100,000/mcL
• Total bilirubin = = 65 mL/min/1.73 m^2 for patients with creatinine levels above institutional normal
• International normalized ratio (INR) =< 1.5 (=< 3 for patients on warfarin)
• Patients who are on warfarin anticoagulation are allowed to participate as long as they fit the following 4 criteria:
• They are therapeutic on a stable warfarin dose
• Their INR target range is no greater than 3
• They are monitored with weekly INR testing
• They have no active bleeding or pathological condition that carries high risk of bleeding Other anticoagulants, including enoxaparin (Lovenox) and fondaparinux (Arixtra) are also permitted
• Women of child-bearing potential and men must use at least one form of contraception (i.e., barrier contraception) at least 4 weeks prior to study entry and then two forms of contraception (i.e barrier contraception and one other method of contraception), for the duration of study participation, and for at least 12 months post-treatment; for appropriate methods of contraception considered acceptable; should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately
• Pregnancy Testing: Women of childbearing potential are required to have a negative serum pregnancy test (with a sensitivity of at least 25 mIU/mL) within 10-14 days (at initial screening/consideration for the trial - serum or urine); a pregnancy test (serum or urine) will be administered every 4 weeks if their menstrual cycles are regular or every 2 weeks if their cycles are irregular while on study within the 24-hour period prior to the administration of GDC-0449; a positive urine test must be confirmed by a serum pregnancy test; prior to dispensing GDC-0449, the investigator must confirm and document the patient's use of two contraceptive methods, dates of negative pregnancy test, and confirm the patient's understanding of the teratogenic potential of GDC-0449
• Ability to understand and the willingness to sign a written informed consent document
• Patients with recurrent disease after curative-intent surgical resection must have sufficient archival material for correlative studies (20 unstained 5 micron slides and 20 unstained 10 micron slides, or an archival tissue block

Exclusion Criteria

• No prior chemotherapy for metastatic pancreatic cancer; patients who have received any chemotherapy and/or radiation therapy in the adjuvant setting must have completed this therapy ≥6 months prior to enrollment on the trial at the time of recurrence
• Patients may not be receiving (or received prior to enrollment) any other investigational agents for metastatic disease
• Patients with known brain metastases should be excluded from this clinical trial because of their poor prognosis and because t