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

Inclusion Criteria:

* 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:

  * Absolute neutrophil count (ANC) ≥ 1.5 x 109/L
  * Platelet count ≥ 100 x 109/L
  * Hemoglobin ≥ 9 g/dL (transfusion independent)
* Renal function, as follows:

  * Creatinine ≤ 2.0 mg/dL
* Hepatic function, as follows:

  * Aspartate aminotransferase (AST) ≤ 2.5 x ULN or ≤ 5 x ULN if known liver metastases.
  * Alanine aminotransferase (ALT) ≤ 2.5 x ULN or ≤ 5 x ULN if known liver metastases
  * Bilirubin ≤ 2 x ULN
* INR \< 1.3 (or ≤ 3 if on warfarin for therapeutic anti-coagulation)

Exclusion Criteria:

* Prior systemic therapy for metastatic pancreatic cancer

  * Subjects who have received adjuvant treatment with gemcitabine and who had relapse metastatically are allowed
  * Subjects with advanced local disease who have received treatment with gemcitabine and in whom progression has been observed with the onset of metastases less than 6 months are excluded
* 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:

  * Curatively resected non-melanomatous skin cancer
  * Other malignancy curatively treated with no known active disease present and no treatment administered for the last 3 years
* 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