Evaluate the Safety and Efficacy of Tafasitamab and Lenalidomide in Combination With Gemcitabine and Oxaliplatin Versus Rituximab in Combination With Gemcitabine and Oxaliplatin in Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma

This trial is comparing two treatment combinations for people with diffuse large B-cell lymphoma (DLBCL) — a type of blood cancer — that has come back or stopped responding. One combination includes tafasitamab and lenalidomide; the other uses rituximab, both combined with gemcitabine and oxaliplatin chemotherapy. **You may be eligible if...** - You are 18 or older - You have confirmed DLBCL (or a related subtype) that has relapsed or is refractory after 1–3 prior treatments - You have at least one measurable area of disease on imaging - You have not had a stem cell transplant, or you are not eligible for one - You are in reasonably good health (ECOG 0–2) - Your organ function is adequate **You may NOT be eligible if...** - You have another active cancer (within the past 3 years) - You have lymphoma in the brain or spinal cord - You have had a prior allogeneic (donor) stem cell transplant - You previously received anti-CD19 treatment or failed gemcitabine/platinum-based therapy - You have serious heart or nerve disease - You have a history of blood clots Talk to your doctor to see if this trial is right for you.