This study will compare the efficacy of simtuzumab (GS-6624) versus placebo in combination with gemcitabine in adults with pancreatic cancer. The treatment phase of this study will be comprised of 2 sequential parts: an open label treatment phase and a double-blinded treatment phase.

Inclusion Criteria:

• Initial diagnosis of metastatic pancreatic cancer must have occurred ≤6 weeks prior to the completion of screening.

• The presence of measurable metastatic pancreatic cancer documented by contrast enhanced CT (or MRI) scan in addition to 1 of the following:

  1. Histological diagnosis of pancreatic adenocarcinoma confirmed by pathologist OR

  2. Pathologist confirmed histological/cytological diagnosis of adenocarcinoma consistent with pancreatic origin in conjunction with either:

     1. The presence of a mass in the pancreas OR
     2. A history of resected pancreatic carcinoma

• Measurable disease per RECIST (ver. 1.1)

• ECOG Performance Status of 0 or 1.

• Adequate hepatic, hematologic and renal functions.

Exclusion Criteria:

• A history or evidence of clinically significant disorder other than metastatic cancer of the pancreas.
• A diagnosis of pancreatic islet neoplasms.
• Subject has undergone major surgery other than diagnosis surgery within 4 weeks of randomization
• Presence of biliary obstruction requiring external drainage
• Brain metastases.
• Unstable cardiovascular function within the last 6 months of screening
• Clinically active liver disease, including active viral hepatitis (HBV or HCV) or cirrhosis
• Known HIV infection.
• Uncontrolled hypertension at Screening
• History or presence of any form of cancer, other than pancreatic cancer, within the 3 years prior to enrollment
• Prior or concurrent anti-tumor therapy (chemotherapy, antibody therapy, molecular targeted therapy, retinoid therapy, hormonal therapy) for the treatment of inoperable locally advanced or metastatic pancreatic cancer; prior radiotherapy and chemotherapy given as pre-operative neoadjuvant therapy or radio sensitizers for locally advanced pancreatic cancer are allowed.
• Uncontrolled systemic fungal, bacterial or viral infection
• Participation in an investigational drug or device trial with therapeutic intent within 30 days prior to study