Phase 2 Study of Plamotamab Combined With Tafasitamab Plus Lenalidomide Versus Tafasitamab Plus Lenalidomide in Relapsed or Refractory (R/R) Diffuse Large-cell B-cell Lymphoma (DLBCL)

Inclusion Criteria: * Histologically confirmed diagnosis of DLBCL, not otherwise specified, including DLBCL arising from low grade lymphoma * CD20+ and CD19+ lymphoma * Archival paraffin embedded tumor tissue or unstained slides must be available for retrospective cell of origin determination * Relapsed or refractory * At least 1 prior systemic line(s) of therapy, one of which must have included multi-agent chemoimmunotherapy that includes an anti-CD20 monoclonal antibody. * At least 1 bidimensionally measurable disease site. The lesion must have a greatest transverse diameter of ≥ 1.5 centimeter (cm) and greatest perpendicular diameter of ≥ 1.0 cm at baseline. The lesion must have a positive finding on positron emission tomography (PET) scan * Ineligible for or refuse hematopoietic stem cell transplantation (HSCT). * Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2 * Completed vaccination for the SARS-CoV-2 virus prior to study entry * Fertile participants must agree to use 2 highly effective methods of birth control during for at least 6 months (male participants) and 8 months (female participants) after the last dose of study treatment Exclusion Criteria: * Any other histological type of lymphoma, including high-grade B-cell lymphoma, including those with myelocytomatosis oncogene (MYC) and B-cell lymphoma 2 (BCL2) and/or B-cell lymphoma 6 (BCL6) rearrangements primary mediastinal (thymic) large B cell (PMBL) or Burkitt lymphoma * A prior diagnosis…