This study is researching an investigational drug, odronextamab, in adult patients B-cell non-Hodgkin's lymphoma (B-NHL). The main purpose of this study is to assess the effectiveness of odronextamab in destroying cancer cells and to learn more about the safety of odronextamab. The study is looking at several other research questions, including: * To see if odronextamab works to destroy cancer cells * Side effects that may be experienced by people taking odronextamab * How odronextamab works in the body * How much odronextamab is present in the blood