Objective: To determine the impact on overall survival (OS) and patient-reported outcomes (PROs) of combining atezolizumab with standard therapy for newly diagnosed stage III/IV ovarian cancer., Methods: The placebo-controlled double-blind randomized phase III IMagyn050/GOG 3015/ENGOT-OV39 trial (NCT03038100) assigned eligible patients to 3-weekly atezolizumab 1200 mg or placebo for 22 cycles with platinum-based chemotherapy and bevacizumab. Coprimary endpoints were progression-free survival (already reported) and OS in the PD-L1-positive and intent-to-treat (ITT) populations, tested hierarchically. Prespecified PRO analyses focused on disease-related abdominal pain and bloating symptoms (European Organisation for Research and Treatment of Cancer QLQ-OV28), functioning, and health-related quality of life (HRQoL) (QLQ-C30)., Results: After 38 months' median follow-up, the OS hazard ratio in the PD-L1-positive population was 0.83 (95% CI, 0.66-1.06; p = 0.13); median OS was not estimable with atezolizumab versus 49.2 months with placebo. The hazard ratio for OS in the ITT population was 0.92 (95% CI, 0.78-1.09; median 50.5 versus 46.6 months, respectively). At week 9, similar proportions of patients in both arms of the neoadjuvant cohort showed ≥10-point improvement from baseline in abdominal pain and bloating, functioning, and HRQoL. In the primary surgery cohort, similar proportions of patients in each arm had improved, stable, or worsened physical and role function and HRQoL from baseline over time. Neither cohort showed differences between arms in treatment-related symptoms or overall side-effect bother., Conclusions: Incorporation of atezolizumab into standard therapy for newly diagnosed ovarian cancer does not significantly improve efficacy or impose additional treatment burden for patients., Clinicaltrials: gov registration: NCT03038100., Competing Interests: Declaration of Competing Interest Sandro Pignata: Personal fees (Roche, AstraZeneca, MSD, PharmaMar, GSK, Clovis, Incyte); Research funding to institution (Roche, MSD, AstraZeneca, Clovis, GSK). Michael Bookman: Administrative and per-capita funding for conduct of the clinical trial paid to institution; Consultation fees paid to institution for ad hoc advisory boards (Merck Sharp & Dohme, AstraZeneca, Genentech/Roche, Clovis Oncology, Seattle Genetics, Aravive, AbbVie) and Data Monitoring Committee (Immunogen). Jalid Sehouli: Research funding (Roche Pharma, AstraZeneca, Bayer, Clovis Oncology, GSK, Lilly, Tesaro); Honoraria (Tesaro, GSK, PharmaMar, AstraZeneca, Clovis Oncology, Bayer, Roche, PharmaMar, Vifor Pharma, Hexal AG, Novartis Pharma); Consulting (Tesaro, Merck/Pfizer, PharmaMar, Clovis Oncology, AstraZeneca, Roche Pharma, GSK, MSD, Eisai, Novocure, Oncoinvent). Richard T. Penson: Institutional research funding as principal investigator (Array BioPharma Inc., AstraZeneca., Eisai Inc., Genentech, Inc., Regeneron, Sanofi-Aventis US LLC, Vascular Biogenics Ltd); Royalties (BMJ Publishing, UptoDate, Elsevier Ltd., Wolters Kluwer Health, Wiley Blackwell); Consulting fees for advisory boards (AstraZeneca, Eisai, GSK Inc., ImmunoGen Inc., Merck & Co., Mersana, Novacure, Roche Pharma, Sutro Biopharma, Vascular Biogenics Ltd); serves on Data and Safety Monitoring Boards (AstraZeneca, EQRx, Roche Pharma). Sakari Hietanen: Consultancy fees (AstraZeneca, Eisai, MSD, GSK); Speaker bureau (AstraZeneca, GSK). Radoslaw Madry: Licences/payments (AstraZeneca); Consulting fees (Roche, MSD, AstraZeneca); Honoraria (GSK, AstraZeneca, Roche); Support for attending meetings and/or travel (AstraZeneca, Roche); Participation on Data Safety Monitoring or Advisory Boards (GlaxoSmithKline, AstraZeneca); Receipt of equipment, materials, drugs, medical writing, gifts, or other services (AstraZeneca). Lyndsay Willmott: Honoraria for speaker bureau (AstraZeneca, Clovis, Eisai, Immunogen, GSK, Merck, Seagen); Honoraria for advisory bureau (Genentech); Participation on advisory boards (AstraZeneca, Clovis, Eisai, Genentech, GSK, Immunogen, Seagen). Tashanna Myers: Personal honorarium for lecture (Immunogen); Honorarium to institution for advisory board (Immunogen). Alain Lortholary: Personal honoraria (AstraZeneca, Clovis Oncology, Tesaro/GSK, Roche, MSD, Novartis). Jessica Thomes-Pepin: Consulting fees for advisory board (Immunogen). Carol Aghajanian: Clinical trial funding to institution (AbbVie, AstraZeneca, Clovis, Genentech/Roche); Consulting fees for advisory boards (AbbVie, Roche/Genentech, Eisai/Merck, AstraZeneca/Merck, Repare Therapeutics); Participation on an advisory board (Blueprint medicine [unrecompensed]); Membership of the Board of Directors (GOG-F [travel cost reimbursement for attending meetings], NRG Oncology [unpaid]). Carolyn McCourt: Royalties (UpToDate). Ashley Stuckey: Royalties (UpToDate). Xiaohua Wu: Honorarium for advisory board (Roche). Larry J. Copeland: DMC membership (Corcept Therapeutics, Inc.); Personal fees for advisory boards (Celsion Corporation, Corcept Therapeutics, Inc., Elevar Therapeutics, GSK Inc., Immunogen, Myriad Genetics, Inc., Rubius Therapeutics, Sorrento Therapeutics, Toray Industries, Inc., VBL Therapeutics, Inc., OncoNova, Inc., Inx Med); Research funding to institution (AbbVie, Advaxis, Agenus, Ajinomoto, Array BioPharm, AstraZeneca, Bristol Myers Squibb, Clovis Oncology, Deciphera Pharma, Eisai, EMD Serono Inc., ERGOMED Clinical Research, Exelixis, Genentech/Roche, Genmab, GSK, Inc., Hoffmann-La Roche, Immunogen, Incyte Corporation, Iovance Biotherapeutics, InVentive Health Clinical, Jansen R&D, Leap Therapetuics, Ludwig Institute for Pharmaceuticals, Merck, Mersana Therapeutics, Inc., Novocure, Novartis Pharmaceuticals, OncoQuest, PRA International, Regeneron Pharmaceuticals, Seattle Genetics, Serono, Sutro Biopharm, Tesaro (GSK), Arcus Biosciences, Inc., Sumitomo Dainippon Pharma Oncology, Cerulean Pharma, Karyopharm, BeiGene USA, Inc., Ovagene, Pfizer Inc., PharmaMar USA Inc.,Precision Therapeutics, Inc., Sanofi, Stemcentrx, Inc., TRACON Pharm, Verastem, Inc.). Yvette He: Employee contracted to provide statistical support to Roche (Parexel). Luciana Molinero, Sheetal Patel, and Victor K. Khor: Employees (Roche/Genentech); Share holders (Roche). Yvonne G. Lin: Employee (Roche/Genentech); Participation on Advisory Board (Intervenn Biosciences, unpaid); Leadership position/committee member (SGO Membership Committee); Share holder (Roche). Kathleen N. Moore: Research funding to institution (PTC Therapeutics, Lilly, Clovis, Genentech, GSK, Verastem), Personal royalties (UptoDate), Personal consulting fees for advisory boards (Aadi, Alkemeres, Aravive, AstraZeneca, Blueprint pharma, Caris, Clovis, Eisai, Genentech/Roche, GSK, Hengrui, Immunogen, Inxmed, IMab, Iovance, Lilly, Merck, Mereo, Mersana, Myriad, Novartis, Novocure, Onconova, OncXerna, Pannavance, Tarveda, VBL Therapeutics, Verastem); Personal honoraria for lectures/presentations/speaker bureau (AstraZeneca, GSK, Immunogen, PRIME, RTP, Medscape, Great Debates and Updates); Support for attending meetings and/or travel (AstraZeneca); Leadership role (GOG Partners Associate director). All authors: Medical writing and article processing charges (F. Hoffmann-La Roche)., (Copyright © 2023. Published by Elsevier Inc.)