Safety and Efficacy Trial of Epcoritamab Combinations in Subjects With B-cell Non-Hodgkin Lymphoma (B-NHL)

The purpose of this trial is to measure the safety and effectiveness of epcoritamab (EPKINLY™), either by itself or together with other therapies, when treating participants with B-cell non-Hodgkin Lymphoma (B-NHL). The aim of the first part of the trial is to identify the most appropriate dose of epcoritamab, and the aim of the second part of the trial is to assess the selected epcoritamab dose in a larger group of participants with B-NHL. All participants in this trial will receive either epcoritamab alone, or epcoritamab combined with another standard treatment regimen, with a total of 10 different treatment arms being studied. Trial details include: * The treatment duration for each participant depends upon which arm of treatment they are assigned to. * The visit frequency for each participant depends upon which arm of treatment they are assigned to, but will be weekly to start for all participants, then will decrease to either: every 2 weeks, or every 3 weeks, or every 4 weeks, or every 8 weeks. * All participants will receive active drug; no one will be given placebo. Participants who receive treatment with epcoritamab will have it injected right under the skin. Participants will receive a different regimen of epcoritamab depending upon which arm of treatment they are assigned. Participants who receive standard treatments will have intravenous (IV) infusions and/or oral administration of those treatments. Participants will receive a different standard treatment regimen depending upon which arm of treatment they are assigned.