The purpose of this study is to evaluate the effect of OPT-822/OPT-821 on improving Progression-Free Survival (PFS) in subjects who have non-progressive epithelial ovarian, fallopian tube, or primary peritoneal cancer after cytoreductive surgery and platinum-based chemotherapy as initial treatment for primary disease or as salvage treatment for first relapse.

Inclusion Criteria:

• Female subjects ≥ 21 years of age with histologically confirmed ≥ stage II epithelial ovarian, fallopian tube, and primary peritoneal cancer at diagnosis
• Who have not progressed after initial treatment with cytoreductive surgery and at least 4 cycles of platinum-based chemotherapy.

OR

• Female subjects ≥ 21 years of age with first relapsed epithelial ovarian, fallopian tube, and primary peritoneal cancer (regardless of stage at diagnosis)
• Who have not progressed after received at least 4 additional cycles of platinum-based chemotherapy with or without having undergone secondary cytoreductive surgery .

Exclusion Criteria:

• Subjects with evidence of disease progression according to the GCIG CA125 criteria or RECIST 1.1 criteria.
• Subjects who are currently receiving any other concomitant anticancer therapy.
• Subjects with evidence of extra-abdominal metastasis.