1. Pathologically confirmed Stage 3 or 4 ovarian cancer (OC) that is either (1) high grade serous, (2) high grade endometrioid, (3) carcinosarcoma, or (4) other epithelial OC with BRCA1/2 deleterious alteration (germline or somatic), excluding tumors that are known mismatch repair deficient/microsatellite instability high, or POLE ultramutated
2. Documented variant (tumor or germline) in BRCA1 or BRCA2, suspected to be pathogenic (deleterious alteration), submission of testing report required, OR

BRCA1/2 wildtype and known HRD deficient tumor; submission of testing report required

1. Must have undergone cytoreductive surgery (either primary or interval)
2. Must have completed first line platinum-based therapy, where: (1) platinum chemotherapy course must have been at least 4 cycles with a maximum of 9 cycles, recommended 6 cycles unless contraindicated, or (2) intravenous, intraperitoneal, or neoadjuvant platinum therapy is permitted
3. ECOG score not greater than 2
4. Adequate organ function as described by Protocol

1. Receipt of any investigational agent while on first course of chemotherapy
2. No disease progression as determined by Investigator after chemotherapy; brain metastases patients may enroll if there is no evidence of progression and are neurologically stable off of steroid therapy
3. Subject is either pregnant or nursing
4. Any active infections requiring parental antibiotics
5. Any evidence of intra-abdominal abscess, abdominal/pelvic fistula, gastrointestinal perforation or obstruction, and/or need for drainage nasogastric or gastrostomy tube
6. Inability to swallow oral medication
7. History of myelodysplastic syndrome and/or acute myeloid leukemia, or history of allogenic bone marrow transplant
8. Concomitant usage of strong or moderate CYP3A inducers
9. Known hypersensitivity to the study drug or any of its associated components