Tafasitamab, Retifanlimab, and Rituximab in Combination With Chemotherapy (Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone) for the Treatment of Diffuse Large B-cell Lymphoma This phase I/II trial tests the safety of tafasitamab, retifanlimab, and rituximab (TRR) as a prephase treatment and in combination with standard chemotherapy consisting off cyclophosphamide, doxorubicin , vincristine, and prednisone (CHOP) in patients with untreated diffuse large B-cell lymphoma. Tafasitamab, retifanlimab, and rituximab are monoclonal antibodies. Tafasitamab binds to a protein called CD19, which is found on B-cells (a type of white blood cell) and some types of cancer cells. Rituximab binds to a protein called CD20, which is also found on B-cells and some cancer cells. These monoclonal