This is a phase 1, open-label, dose-escalation clinical trial to evaluate the safety and tolerability of ASG-5ME and identify the maximum tolerated dose in patients with pathologically confirmed metastatic pancreatic adenocarcinoma, and to evaluate safety and tolerability in patients with relapsed or refractory gastric adenocarcinoma.

Inclusion Criteria:

• Pathologically confirmed metastatic pancreatic adenocarcinoma or pathologically confirmed AGS-5-positive gastric or gastric esophageal junction adenocarcinoma
• Measurable disease (at least one nonresectable, non-nodal lesion greater than or equal to 10 mm in longest diameter or nodal lesion greater than or equal to 15 mm in shortest axis)
• ECOG performance status of 0 or 1
• May be untreated or have previously received treatment for pancreatic adenocarcinoma or must have relapsed or refractory disease following 1 prior systemic therapy for metastatic gastric adenocarcinoma. For patients who have previously received treatment, it must be at least 2 weeks since the last systemic therapy or radiation, and at least 4 weeks since treatment with any monoclonal antibody (other than bevacizumab).

Exclusion Criteria:

• Evidence or history of central nervous system metastases
• History of another primary malignancy that has not been in remission for at least 3 years
• Documented history of a cerebral vascular event, unstable angina, myocardial infarction, or cardiac symptoms consistent with NYHA Class III-IV within 6 months prior