A Study of AGS-1C4D4 Given in Combination With Gemcitabine in Subjects With Metastatic Pancreatic Cancer

* Pathologically confirmed metastatic adenocarcinoma of the pancreas (AJCC Stage IV). Subjects with islet cell neoplasms are excluded

* Non-measurable or measurable disease based on the RECIST criteria

* Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1

* Life expectancy of > 3 months

* Hematologic function, as follows:

* Renal function, as follows:

* Hepatic function, as follows:

* INR < 1.3 (or ≤ 3 if on warfarin for therapeutic anti-coagulation)

* Prior systemic therapy for metastatic pancreatic cancer

* Chemotherapy and/or radiation within 4 weeks of study enrollment

* Prior monoclonal antibody therapy within 60 days of study enrollment

* Known brain or leptomeningeal disease

* History of other primary malignancy, unless:

* Active angina or Class III or IV Congestive Heart Failure (New York Heart Association CHF Functional Classification System)

* Use of any investigational product within 4 weeks of study enrollment

* Major surgery (that requires general anesthesia) within 4 weeks before study enrollment

* Women who are pregnant (confirmed by positive pregnancy test) or lactating

* Man or woman of childbearing potential not consenting to use adequate contraceptive precautions during the course of the study and for 4 weeks after the last AGS-1C4D4 and/or gemcitabine infusion administration

* Subject known to be human immunodeficiency, hepatitis B or hepatitis C virus positive

* Active serious infection not controlled with antibiotics