This is the first in human study of AGS-8M4 given every 2 weeks to subjects with advanced ovarian cancer. AGS-8M4 will be administered as an IV infusion until the disease worsens.

All Subjects will receive AGS-8M4 treatment. Subjects will be enrolled sequentially into 1 of the 4 planned dose cohorts according to a standard dose escalation study design. A disease assessment will be performed at study week 9 (+/- 3 days). The assessment will be based on clinical signs and symptoms, changes in radiographic images, and changes in CA-125 levels. Subjects without evidence of disease progression may continue to receive AGS-8M4 during the extended treatment period at the dose and schedule of their assigned cohort until disease progression intolerability of AGS-8M4 or consent withdrawal. For subjects that continue dosing, disease assessments will be performed every 8 weeks during the extended treatment period. A safety follow-up visit will occur 4 weeks after the last infusion of AGS-8M4.

Inclusion Criteria:

• Subjects with recurrent disease or histologically or cytologically confirmed Stage III/IV diagnosis of epithelial ovarian cancer, fallopian tube cancer, or primary peritoneal carcinoma
• Subjects must have received at least one prior platinum containing regimen and one of the following: persistent disease (either stable disease, partial response or nonmeasureable disease after first line therapy) or progressive disease at anytime

Exclusion Criteria:

• No epithelial ovarian tumors of low malignant potential
• Active infection requiring treatment with systemic anti-infectives within 72 hours of screening
• Use of any investigational drug within 30 days prior to screening or 5 half-lives of the prior investigational drug (whichever is longer)
• Prior monoclonal antibody therapy