Study of Chemotherapy With Pembrolizumab (MK-3475) Followed by Maintenance With Olaparib (MK-7339) for the First-Line Treatment of Women With BRCA Non-mutated Advanced Epithelial Ovarian Cancer (EOC) (MK-7339-001/KEYLYNK-001/ENGOT-ov43/GOG-3036)

Inclusion Criteria

• Has histologically confirmed International Federation of Gynecology and Obstetrics (FIGO) Stage III or Stage IV EOC (high-grade predominantly serous, endometrioid (any grade), carcinosarcoma, mixed mullerian with high-grade serous component, clear cell, or low-grade serous OC), primary peritoneal cancer, or fallopian tube cancer
• Has just completed primary debulking surgery or is eligible for primary debulking surgery or is a potential candidate for interval debulking surgery
• Is a candidate for carboplatin and paclitaxel chemotherapy, to be administered in the adjuvant or neoadjuvant setting
• Candidates for neoadjuvant chemotherapy, has a cancer antigen 125 (CA-125) (kilounits/L):carcinoembryonic antigen (CEA; ng/mL) ratio greater than or equal to 25
• Is able to provide a newly obtained core or excisional biopsy of a tumor lesion for prospective testing of BRCA1/2 and Programmed Cell Death-Ligand 1 (PD-L1) tumor markers status prior to randomization
• Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, as assessed within 7 days prior to initiating chemotherapy in the lead-in period and within 3 days prior to Day 1 of Cycle 1
• Female participants are not pregnant, not breastfeeding, and at least 1 of the following conditions applies: a.) Not a woman of childbearing potential (WOCBP) OR b.) Is a WOCBP and using a contraceptive method that is highly effective, with low user dependency, or be abstinent from heterosexual intercourse as their preferred and usual lifestyle, during the Treatment Period and for at least 120 days following the last dose of pembrolizumab (or pembrolizumab placebo) and bevacizumab (if administered), at least 180 days following the last dose of olaparib (or olaparib placebo), and at least 210 days following the last dose of chemotherapy and agrees not to donate eggs (ova, oocytes) to others or freeze/store for her own use for the purpose of reproduction during this period. The investigator should evaluate the potential for contraceptive method failure in relationship to the first dose of study treatment. A WOCBP must have a negative highly sensitive pregnancy test within either 24 hours (urine) or 72 hours (serum) before the first dose of study treatment. If a urine test cannot be confirmed as negative, a serum pregnancy test is required. The investigator is responsible for review of medical history, menstrual history, and recent sexual activity to decrease the risk for inclusion of a woman with an early undetected pregnancy. Contraceptive use by women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies
• Has adequate organ function

Exclusion Criteria

• Has mucinous, germ cell, or borderline tumor of the ovary
• Has a known or suspected deleterious mutation (germline or somatic) in either BRCA1 or BRCA2
• Has a history of non-infectious pneumonitis that required treatment with steroids or currently has pneumonitis
• Has either myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) or has features suggestive of MDS/AML
• Has a known additional malignancy that is progressing or has required active treatment in the last 3 years Note: Participants with basal cell carcinoma of the skin, squamous cell carcinoma of the skin, or carcinoma in situ (e.g. ductal carcinoma in situ, cervical carcinoma in situ) that has undergone potentially curative therapy are not excluded.
• Has ongoing Grade 3 or Grade 4 toxicity, excluding alopecia, following chemotherapy administered during the lead-in period
• Has known active central nervous system metastases and/or carcinomatous meningitis. Participants with brain metastases may participate provided they were previously treated (except with chemotherapy) and are radiologically stable, clinically stable, and no steroids were used for the management of symptoms related to brain metastases within 14 days prior to randomization. Stable brain met