A Study to Compare How Well Odronextamab Combined With Chemotherapy Works and How Safe it is Against Rituximab Combined With Chemotherapy, in Adult Patients With Previously Untreated Diffuse Large B-cell Lymphoma

Key Inclusion Criteria: 1. Previously untreated participants for lymphoma with documented Cluster of Differentiation 20+ (CD20+) DLBCL, as described in the protocol OR relapsed or refractory DLBCL, for whom next available standard of care therapy is not available or deemed ineligible according to the investigator (Part 1A only) 2. Measurable disease with at least one nodal lesion or at least one extranodal lesion, as described in the protocol 3. Eastern Cooperative Oncology Group (ECOG) performance status ≤2 4. Life expectancy ≥ 12 months 5. International Prognostic Index (IPI) of 3 to 5 (part 1 only) and ≥2 (part 2) for untreated DLBCL only 6. Adequate hematologic and organ function, as defined in the protocol. Key Exclusion Criteria: 1. Primary Central Nervous System (CNS) lymphoma or known involvement by non-primary CNS NHL and history or current relevant CNS pathology 2. Another active malignancy, significant active disease or medical condition, as described in the protocol 3. Peripheral neuropathy Grade ≥3 4. Treatment with any systemic anti-lymphoma therapy, except for participants with Relapsed/Refractory (R/R) DLBCL and participants with DLBCL transformed from an indolent lymphoma after treatment with systemic anti-lymphoma therapy. 5. Any other therapy or investigational treatment within 28 days or 5 half-lives of the drug, whichever is shorter, prior to the start of study treatment 6. Recent major surgery, prior organ transplantation, or standard radiotherapy, as described in the protocol 7. Allergy/hypersensitivity to study drugs, as described in the protocol 8. Infections such as any active infection (bacterial, viral, fungal, mycobacterial, parasitic or other), active Coronavirus Disease (COVID-19) infection, uncontrolled infection with Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV), or Hepatitis C Virus (HCV), Cytomegalovirus (CMV) infection, as described in the protocol. Note: Other protocol-defined Inclusion/ Exclusion criteria apply