Background: The current standard of care for patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) is R CHOP; however, approximately 40% of patients are not cured. The CD79b-targeting antibody-drug conjugate, polatuzumab vedotin, is approved in relapsed/refractory DLBCL in combination with bendamustine and rituximab, and has also demonstrated promising first line activity and safety when combined with rituximab, cyclophosphamide, doxorubicin, and prednisone (pola-R-CHP) in a Phase Ib/II study (Tilly, et al. Lancet Oncol 2019). Thus, in the Phase III POLARIX study (NCT03274492) we compared pola-R-CHP with R-CHOP in patients with previously untreated DLBCL. Methods: In this double-blind, placebo-controlled, international study, patients with previously untreated DLBCL and an International Prognostic Index (IPI) of 2-5 were randomized 1:1 to receive six cycles of pola-R-CHP (with a vincristine placebo) or R-CHOP (with a polatuzumab vedotin placebo); all patients also received two additional cycles of rituximab. Patients received polatuzumab vedotin 1.8mg/kg or vincristine 1.4mg/m² administered on Day 1, plus intravenous rituximab 375mg/m2, cyclophosphamide 750mg/m², doxorubicin 50mg/m², and placebo on Day 1, and oral prednisone 100mg once daily on Days 1-5. The primary endpoint was investigator-assessed progression-free survival (PFS). Secondary endpoints included investigator-assessed event-free survival (EFS), independent review committee-assessed complete response (CR) rate at the end of treatment by positron emission tomography-computed tomography (PET-CT), disease-free survival (DFS), overall survival (OS), and safety. Results: Overall, 879 patients were randomized, 440 to pola-R-CHP and 439 to R-CHOP. Median age was 65 (range 19-80) years, and the majority of patients had IPI 3-5 (62.0%). At the data cut-off of June 28, 2021, and after a median follow-up of 28.2 months, PFS was superior with pola-R-CHP vs R CHOP (hazard ratio [HR] 0.73; 95% confidence interval [CI]: 0.57-0.95; P Conclusion: The pola-R-CHP combination demonstrated a 27% reduction in the relative risk of disease progression, relapse, or death compared with R-CHOP, with a similar safety profile in the first-line treatment of patients with DLBCL. Disclosures Tilly: Karyopharm: Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees, Other: Meeting attendance and travel, Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees. Morschhauser: AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; AstraZenenca: Membership on an entity's Board of Directors or advisory committees; Epizyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Chugai: Honoraria; Genentech, Inc.: Consultancy; Janssen: Honoraria; Genmab: Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy; Incyte: Membership on an entity's Board of Directors or advisory committees. Sehn: Novartis: Consultancy; Genmab: Consultancy; Debiopharm: Consultancy; Teva: Consultancy, Research Funding; Roche/Genentech: Consultancy, Research Funding; AbbVie: Consultancy; Acerta: Consultancy; Amgen: Consultancy; Apobiologix: Consultancy; AstraZeneca: Consultancy; Celgene: Consultancy; Gilead: Consultancy; Incyte: Consultancy; Janssen: Consultancy; Kite: Consultancy; Karyopharm: Consultancy; Lundbeck: Consultancy; Merck: Consultancy; Morphosys: Consultancy; Sandoz: Consultancy; Seattle Genetics: Consultancy; Takeda: Consultancy; TG Therapeutics: Consultancy; Verastem: Consultancy. Friedberg: Bayer: Membership on an entity's Board of Directors or advisory committees; Acerta: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Trněný: Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Portola: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria. Sharman: AbbVie: Consultancy; AstraZeneca: Consultancy; BeiGene: Consultancy; Bristol-Myers Squibb: Consultancy; Lilly: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy; TG Therapeutics: Consultancy; Centessa: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Genentech, Inc.: Consultancy; Velos: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees. Herbaux: Takeda: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Honoraria; Janssen: Honoraria. Burke: Verastem: Consultancy; AstraZeneca: Consultancy; Morphosys: Consultancy; Adaptive Biotechnologies: Consultancy; Epizyme: Consultancy; Kura: Consultancy; AbbVie: Consultancy; BeiGene: Consultancy, Speakers Bureau; Kymera: Consultancy; Bristol-Myers Squibb: Consultancy; X4 Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy, Speakers Bureau; Gilead: Consultancy; Genentech, Inc.: Consultancy. Matasar: Memorial Sloan Kettering Cancer Center: Current Employment; Merck Sharp & Dohme: Consultancy, Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Genentech, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Research Funding; GlaxoSmithKline: Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Research Funding; IGM Biosciences: Research Funding; Pharmacyclics: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Rocket Medical: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Research Funding; ImmunoVaccine Technologies: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Teva: Consultancy, Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Consultancy, Honoraria. Rai: Chugai Pharmaceutical Co., Ltd: Speakers Bureau; ONO Pharmaceutical Co., Ltd: Speakers Bureau; Janssen Pharmaceutical: Speakers Bureau; Eisai Co., Ltd: Speakers Bureau. Izutsu: AbbVie: Honoraria; Allergan Japan: Honoraria; AstraZeneca: Honoraria, Research Funding; Bayer: Research Funding; BeiGene: Research Funding; Celgene: Honoraria, Research Funding; Chugai: Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Research Funding; Eisai: Honoraria, Research Funding; Fuji Film Toyama Chemical: Honoraria; Genmab: Honoraria, Research Funding; Huya Biosciences: Research Funding; Incyte: Research Funding; Janssen: Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; MSD: Research Funding; Novartis: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Pfizer: Research Funding; Solasia: Research Funding; Symbio: Honoraria; Takeda: Honoraria, Research Funding; Yakult: Research Funding. Mehta-Shah: C4 Therapeutics: Consultancy; Kiowa Hakko Kirin: Consultancy; Karyopharm: Consultancy; Ono Pharmaceuticals: Consultancy; Secura Bio: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; AstraZeneca: Research Funding; Bristol-Myers Squibb: Research Funding; Celgene: Research Funding; Innate Pharmaceuticals: Research Funding; Roche/Genentech: Research Funding; Corvus Pharmaceuticals: Research Funding; Verastem: Research Funding. Oberic: Celgene: Honoraria; F. Hoffmann-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel; Janssen: Honoraria, Other: Support for attending meetings and/or travel; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel; AbbVie: Other: Support for attending meetings and/or travel; Incyte: Membership on an entity's Board of Directors or advisory committees. Jurczak: Maria Sklodowska-Curie National Research Institute of Oncology: Current Employment; Jagiellonian University: Ended employment in the past 24 months. Greil: Sandoz: Honoraria, Research Funding; Amgen: Honoraria, Other: Travel, Accommodations, Expenses, Research Funding; AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses; Merck Sharp & Dohme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses, Research Funding. Pinto: Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel; Gilead Sciences: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel; MSD: Honoraria; Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Other: Support for attending meetings and/or travel; F. Hoffmann-La Roche Ltd: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Speakers Bureau. Abrisqueta Costa: Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; F. Hoffmann-La Roche Ltd: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees. Hirata: Genentech, Inc.: Current Employment; Genentech/Roche: Current holder of stock options in a privately-held company. Jiang: Genentech, Inc.: Current Employment; F. Hoffmann-La Roche Ltd: Current equity holder in publicly-traded company. Yan: F. Hoffmann-La Roche Ltd: Current Employment, Current equity holder in publicly-traded company. Lee: Genentech, Inc.: Current Employment; F. Hoffmann-La Roche Ltd: Current equity holder in publicly-traded company. Flowers: AbbVie: Consultancy, Research Funding; Bayer: Consultancy, Research Funding; BeiGene: Consultancy; Celgene: Consultancy, Research Funding; Denovo Biopharma: Consultancy; Epizyme: Consultancy; Roche/Genentech: Consultancy, Research Funding; Genmab: Consultancy; Gilead: Consultancy, Research Funding; Karyopharm: Consultancy; Pharmacyclics/Janssen: Consultancy; Seattle Genetics: Consultancy; Spectrum: Consultancy; 4D: Research Funding; Acerta: Research Funding; Adaptimmune: Research Funding; Allogene: Research Funding; Amgen: Research Funding; Cellectis: Research Funding; EMD: Research Funding; Guardant: Research Funding; Iovance: Research Funding; Janssen: Research Funding; Kite: Research Funding; Morphosys: Research Funding; Nektar: Research Funding; Novartis: Research Funding; Pfizer: Research Funding; Sanofi: Research Funding; Takeda: Research Funding; TG Therapeutics: Research Funding; Xencor: Research Funding; Ziopharm: Research Funding; Burroughs Wellcome Fund: Research Funding; Eastern Cooperative Oncology Group: Research Funding; National Cancer Institute: Research Funding; Cancer Prevention and Research Institute of Texas: CPRIT Scholar in Cancer Research: Research Funding; Pharmacyclics: Research Funding. Salles: Bayer: Honoraria; AbbVie: Consultancy, Honoraria; BeiGene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb/Celgene: Consultancy, Honoraria; Debiopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Epizyme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genmab: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Ipsen: Consultancy; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Kite/Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Loxo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Consultancy; Morphosys: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Rapt: Consultancy, Membership on an entity's Board of Directors or advisory committees; Regeneron: Consultancy, Honoraria; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Velosbio: Consultancy, Membership on an entity's Board of Directors or advisory committees; Allogene: Consultancy. OffLabel Disclosure: Polatuzumab vedotin is an antibody-drug conjugate targeting CD79b on malignant B-cells. Polatuzumab vedotin in combination with bendamustine and rituximab (pola-BR) improved complete response rate and overall survival compared with BR alone in patients with relapsed/refractory diffuse large B-cell lymphoma. Pola-BR is approved for the treatment of adult patients with relapsed or refractory diffuse large B-cell lymphoma, not otherwise specified, after at least two prior therapies.