REGN9220 in Combination With Odronextamab in Adult Participants With Relapsed or Refractory Aggressive B-Cell Non-Hodgkin Lymphomas (BCNHLs)

This study will test a new experimental study drug called REGN9220 with a Regeneron drug called odronextamab (both called "study drug") to see if it can help treat people with aggressive BCNHL that has either come back/gotten worse or has not responded to previous treatment. The study is looking at: * What side effects REGN9220 might cause when given with odronextamab * How well REGN9220 works when given with odronextamab * How much REGN9220 is in the blood at different times when given with odronextamab * If the body makes antibodies to REGN9220 when given with odronextamab, this may cause the REGN9220 to not work as well * How the body and immune system changes after having REGN9220 given with odronextamab, which can help researchers understand why REGN9220 given with odronextamab works better in some people than others * What is the best dose of REGN9220 when given with odronextamab

Key Inclusion Criteria: 1. Documented Cluster of Differentiation (CD)20+ aggressive B-cell non-Hodgkin lymphoma that is relapsed or refractory 2. Measurable disease on cross sectional imaging 3. Eastern Cooperative Oncology Group (ECOG) performance status 0-1 4. Adequate organ function (hematologic, hepatic, and renal) 5. Availability of tumor tissue for analysis for submission to central laboratory is required for trial enrollment 6. Willingness to comply with contraception requirements and study procedures Key Exclusion Criteria: 1. Diagnosis of Mantle Cell Lymphoma (MCL) or Central Nervous System (CNS) lymphoma 2. Significant CNS disorders 3. Active/uncontrolled infections 4. Prior treatment with anti-CD20 x anti-CD3 bispecific antibody 5. Recent cancer therapy or major surgery 6. Drug hypersensitivity 7. Significant comorbidities 8. Pregnancy/breastfeeding NOTE: Other Protocol-defined Inclusion/Exclusion Criteria Apply