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

Inclusion Criteria:

- Previously untreated participants with cluster of differentiation 20 (CD20)-positive
DLBCL, including one of the following diagnoses by 2016 World Health Organization
(WHO) classification of lymphoid neoplasms: DLBCL, not otherwise specified (NOS)
including germinal center B-cell type, activated B-cell type; T-cell/histiocyte-rich
large B-cell lymphoma; Epstein-Barr virus-positive DLBCL, NOS; anaplastic lymphoma
kinase (ALK)-positive large B-cell lymphoma; human herpesvirus-8 (HHV8)-positive
DLBCL, NOS; High-grade B-cell lymphoma with MYC and B-cell lymphoma 2 (BCL2) and/or
B-cell lymphoma 6 (BCL6) rearrangements (double-hit or triple-hit lymphoma);
High-grade B-cell lymphoma, NOS

- Availability of archival or freshly collected tumor tissue before study enrolment

- International Prognostic Index (IPI) score of 2-5

- Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1, or 2

- Life expectancy greater than or equal to (>/=)12 months

- Left ventricular ejection fraction (LVEF) >/= 50 percent (%) on cardiac multiple-gated
acquisition (MUGA) scan or cardiac echocardiogram (ECHO)

- Adequate hematologic function

Exclusion Criteria:

- 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