General Inclusion Criteria:

          -  ≥ 18 years of age

          -  Adequate organ function

          -  Life expectancy ≥ 16 weeks

          -  Women of childbearing potential must have a negative serum pregnancy test

          -  High-grade serous or endometrioid epithelial ovarian, fallopian tube, or primary
             peritoneal cancer

          -  Received 1 or 2 prior regimens, including ≥ 1 prior platinum-based therapy and have
             platinum-sensitive disease

          -  Relapsed/progressive disease (confirmed by radiologic assessment)

          -  Willing and able to have a biopsy of tumor at screening and after 4 weeks of
             treatment.

          -  Measurable disease (RECIST v1.1)- Cohort A1 only

          -  ECOG performance status of 0 to 1

        General Exclusion Criteria

          -  Active second malignancy

          -  Central nervous system brain metastases

          -  Evidence of interstitial lung disease, active pneumonitis, myocarditis, or history of
             myocarditis.

          -  Active, known or suspected autoimmune disease (eg, autoimmune hepatitis).

          -  Condition requiring systemic treatment with either corticosteroids

          -  Prior treatment with a PARP inhibitor or immune checkpoint inhibitor.

          -  Non-epithelial tumors (pure sarcomas) or ovarian tumors with low malignant potential
             (ie, borderline tumors) or mucinous tumors. Mixed Mullerian tumors/carcinosarcomas are
             allowed.