Inclusion Criteria:  Patient is female and ≥18 years of age. Patient has histologically confirmed diagnosis of EOC (ie, high-grade serous, endometrioid of any grade, clear cell), fallopian tube cancer, or primary peritoneal cancer. Patient has platinum-resistant/refractory disease, defined as disease progression within 180 days following the last administered dose of platinum therapy beyond first-line setting (resistant) or lack of response or disease progression while receiving the most recent platinum-based therapy (refractory). Patient must have progressed radiographically on or after their most recent line of anticancer therapy. Patient must have received at least 1 prior line of systemic anticancer therapy in the platinum sensitive setting, and no more than 5 prior lines of systemic anticancer therapy in the platinum-resistant setting. Patient must have received at least 1 line of therapy containing bevacizumab. Patient has at least one measurable lesion that qualifies as a target lesion based on RECISTv1.1. Patient is willing to undergo a pre-treatment tumor biopsy or provide qualifying archival tumor tissue.  Exclusion Criteria:  Patient has primary platinum-refractory disease or primary platinum resistance, defined as disease progression during first-line platinum-based therapy (refractory) or disease progression <3 months after completion of first-line platinum-based therapy (resistant). Patient has histologically confirmed diagnosis of EOC with mucinous or carcinosarcoma subtype. Patient has nonepithelial tumor (eg, germline or stromal cell tumor) or ovarian tumor with low malignant potential (ie, borderline or low-grade serous tumor). Patient requires fluid drainage (eg, paracentesis, thoracentesis, pericardiocentesis) of ≥500 mL within 6 weeks of first dose of study drug. Patient has received prior IL-2-based or IL-15-based cytokine therapy; patient has had exposure, including intralesional, to IL-12 or analogs thereof. Patient has prior exposure to any anti-PD1/PD-L1 therapy.