Pembrolizumab and Bevacizumab With Chemotherapy Followed by Pembrolizumab, Bevacizumab and Olaparib in Recurrent Ovarian Cancer

Inclusion Criteria:

1. Participant is at least 20 years of age on the day of signing informed consent withhistologically confirmed epithelial ovarian cancer (excluding borderline ovariantumor) excluding mucinous carcinoma.
2. Participant has received only one regimen of PBC (3 cycles or more) as prior therapywith clinical CR (determined by negative clinical examination and a normal CA-125level).
3. Participant has documentation of progressive disease at least 6 months from completionof PBC (platinum-sensitive).
4. Participant with measurable disease based on RECIST 1.1 at screening
5. Participant is able to provide a core or excisional biopsy of a tumor for testing ofPD-L1 status, etc.
6. Participant with Eastern Cooperative Oncology Group (ECOG) PS of 0 to 1 at thescreening
7. Participant has a life expectancy of at least 12 weeks as determined by theinvestigators.
8. Participant has adequate organ function.

Exclusion Criteria:

1. A Women of Childbearing Potential (WOCBP) who has a positive urine pregnancy test atscreening. If the urine test is positive or cannot be confirmed as negative, a serumpregnancy test will be required.
2. Participant has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2agent or with an agent directed to another stimulatory or co-inhibitory T-cellreceptor (eg, CTLA-4, OX-40, CD137).
3. Participant has received prior systemic anti-cancer therapy including investigationalagents within 4 weeks prior to the first dose of study drug.
4. Participant has received prior radiotherapy within 2 weeks of the first dose of studydrug.
5. Participant has received major surgery within 4 weeks prior to the first dose of studydrug.
6. Participant has received a live vaccine or live-attenuated vaccine within 30 daysprior to the first dose of study drug. Administration of killed vaccines is allowed.
7. Participant is currently participating in or has participated in a study of aninvestigational agent or has used an investigational device within 4 weeks prior tothe first dose of study drug.
8. Participant has a diagnosis of immunodeficiency or is receiving chronic systemicsteroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or anyother form of immunosuppressive therapy within 7 days prior to the first dose of studydrug.
9. Participant has a known additional malignancy that is progressing or has requiredactive treatment within the past 3 years.
10. Participant has known active CNS metastases and/or carcinomatous meningitis.
11. Participant has severe hypersensitivity (≥Grade 3) to the study treatment and/or anyof its excipients.
12. Participant has active autoimmune disease that has required systemic treatment in thepast 2 years (i.e. with use of disease modifying agents, corticosteroids orimmunosuppressive drugs).
13. Participant has a history of (non-infectious) pneumonitis/interstitial lung diseasethat required treatment with steroids or has current pneumonitis/interstitial lungdisease.
14. Participant has an active infection requiring systemic therapy.
15. Participant has a known history of Human Immunodeficiency Virus (HIV) infection.
16. Participant has a known history of Hepatitis B (defined as Hepatitis B surface antigen [HBsAg] reactive) or known active Hepatitis C virus (defined as HCV RNA [qualitative]is detected) infection.
17. Participant has received colony-stimulating factors (granulocyte colony stimulatingfactor [G-CSF], granulocyte macrophage colony-stimulating factor [GM-CSF] orrecombinant erythropoietin) within 2 weeks prior to the first dose of study drug.
18. Participant has clinically serious cardiovascular/cerebrovascular diseases (eg,cerebrovascular accident/stroke [less than 6 month prior to enrollment], myocardialinfarction [less than 6 month prior to enrollment], uncontrolled and potentiallyreversible cardiac conditions [unstable ischemia, uncontrolled symptomatic arrhythmia,congestive heart failure, QTcF prolongation >500 msec, electrolyte disturbances,hypertension defined as systolic >150 mmHg or diastolic >90 mmHg etc.] or participanthas congenital long QT syndrome).
19. Participant has known abdominal fistula, gastrointestinal fistula or gastrointestinalperforation and/or higher risks of bleeding.
20. Participant has either myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) orhas features suggestive of MDS/AML.
21. Participant is currently receiving either strong (eg, itraconazole, telithromycin,clarithromycin, protease inhibitors boosted with ritonavir or cobicistat, indinavir,saquinavir, nelfinavir, boceprevir, telaprevir) or moderate (eg, ciprofloxacin,erythromycin, diltiazem, fluconazole, verapamil) inhibitors of cytochrome P450 (CYP)3A4 that cannot be discontinued prior to the first dose of study drug.
22. Participant is currently receiving either strong (eg, phenobarbital, enzalutamide,phenytoin, rifampicin, rifabutin, rifapentine, carbamazepine, nevirapine, and StJohn's Wort) or moderate (eg, bosentan, efavirenz, modafinil) inducers of CYP3A4 thatcannot be discontinued prior to the first dose of study drug.
23. Participant is either unable to swallow orally administered medication or has agastrointestinal disorder affecting absorption (eg, gastrectomy, partial bowelobstruction, malabsorption).
24. Participant has known psychiatric or substance abuse disorders that would interferewith cooperation with the requirements of the trial.
25. Participant is pregnant or breastfeeding or expecting to conceive or father childrenwithin the projected duration of the study, starting with the screening visit through 210 days after the last dose of study treatment.
26. Participant has had an allogenic tissue/solid organ transplant.
27. Participant has a history or current evidence of any condition, therapy, or laboratoryabnormality that might confound the results of the study, interfere with theparticipant's participation for the full duration of the study, or is not in the bestinterest of the participant to participate, in the opinion of the investigators.