A Study Comparing the Efficacy and Safety of Polatuzumab Vedotin With Rituximab-Cyclophosphamide, Doxorubicin, and Prednisone (R-CHP) Versus Rituximab-Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone (R-CHOP) in Participants With Diffuse Large B-Cell Lymphoma

History of severe allergic or anaphylactic reactions to humanized or murine monoclonal antibodies or known sensitivity or allergy to murine products

Contraindication to any of the individual components of CHOP, including prior receipt of anthracyclines

Prior organ transplantation

Current Grade greater than (\>) 1 peripheral neuropathy by clinical examination

Demyelinating form of Charcot-Marie-Tooth disease

History of indolent lymphoma

History of follicular lymphoma grade 3B

B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and classical Hodgkin lymphoma (grey-zone lymphoma)

Primary mediastinal (thymic) large B-cell lymphoma

Burkitt lymphoma

Prior treatment with cytotoxic drugs within 5 years of screening for any condition (example \[e.g.\], cancer, rheumatoid arthritis) or prior use of any anti-CD20 antibody

Prior use of any monoclonal antibody within 3 months of the start of Cycle 1

Prior therapy for DLBCL, with the exception of nodal biopsy

Corticosteroid use \>30 mg/day of prednisone or equivalent, for purposes other than lymphoma symptom control

Participants with central nervous system (CNS) lymphoma (primary or secondary involvement), primary effusion DLBCL, and primary cutaneous DLBCL

Vaccination with live vaccines within 28 days prior to the start of Cycle 1

Any investigational therapy within 28 days prior to the start of Cycle 1

History of other malignancy that could affect compliance with the protocol or interpretation of results

Evidence of significant, uncontrolled, concomitant diseases that could affect compliance with the protocol or interpretation of results, including significant cardiovascular disease or pulmonary disease

Recent major surgery (within 4 weeks prior to the start of Cycle 1), other than for diagnosis

History or presence of an abnormal electrocardiogram (ECG) that is clinically significant in the investigator's opinion, including complete left bundle branch block, second- or third-degree heart block, or evidence of prior myocardial infarction

Known active bacterial, viral, fungal, mycobacterial, parasitic, or other infection (excluding fungal infections of nail beds) at study enrollment or significant infections within 2 weeks before the start of Cycle 1

Clinically significant liver disease, including active viral or other hepatitis, current alcohol abuse, or cirrhosis

Prior radiotherapy to the mediastinal/pericardial region

Participants with suspected active or latent tuberculosis

Positive test results for chronic hepatitis B and hepatitis C infection

Known history of human immunodeficiency virus (HIV) seropositive status

Positive results for the human T-lymphotrophic 1 virus (HTLV-1)

Participants with a history of progressive multifocal leukoencephalopathy

What this study is about