Background: Phase III trial data have shown a significant benefit by the addition of a maintenance treatment with niraparib, irrespective of BRCA or HRD status, in patients with advanced high-grade ovarian cancers; and, a significant benefit of the combination of olaparib and bevacizumab compared with bevacizumab monotherapy in HRD positive patients. However, it is unclear whether a PARP inhibitor monotherapy is sufficient, or if the addition of bevacizumab is needed. Primary Objectives: This trial will investigate if the treatment strategy of carboplatin/paclitaxel/bevacizumab/niraparib is superior to the treatment of carboplatin/paclitaxel/niraparib in an all-comer population. Study Hypothesis: Adding bevacizumab to chemotherapy followed by niraparib maintenance improves progression-free survival in patients with newly diagnosed advanced ovarian cancer. Trial Design: AGO-OVAR 28/ENGOT-ov57 is an international, multicenter, randomized, prospective phase III trial within the the European Network for Gynecological Oncological Trial (ENGOT), led by the Arbeitsgemeinschaft Gynäkologische Onkologie (AGO) study group. All patients should have completed the first cycle of chemotherapy (carboplatin and paclitaxel) as part of the Study Run-In-Period. Prior to day 1 of cycle 2, patients with a valid central tumor BRCA (tBRCA) test result were randomized in a 1:1 ratio into either: Arm 1, to receive five additional cycles of carboplatin and paclitaxel q21d, followed by niraparib for up to 3 years; or Arm 2, to receive five additional cycles of carboplatin and paclitaxel plus bevacizumab q21d, followed by bevacizumab q21d (for up to 1 year), and niraparib for up to 3 years. Major Inclusion/Exclusion Criteria: The trial population is composed of adult patients with newly diagnosed, advanced high-grade epithelial ovarian cancer, primary peritoneal cancer, or fallopian tube cancer FIGO III/IV (except FIGO IIIA2 without nodal involvement). Patients who are scheduled for neoadjuvant chemotherapy and interval debulking surgery are also eligible for the trial. Primary Endpoint: The primary endpoint is progression-free survival. Sample Size: The study plans to recruit 970 patients (485 patients in each arm). Estimated Dates For Completing Accrual And Presenting Results: The Last-Patient-In is expected to be enrolled in September 2024, with presentation of the primary endpoint in 2028.