Evaluate the Safety and Efficacy of Tafasitamab Combined With Lenalidomide in Patients With Relapsed or Refractory DLBCL

This trial is testing the combination of two drugs — tafasitamab (an antibody that targets cancer cells) and lenalidomide (an immune-modulating drug) — in people with diffuse large B-cell lymphoma (DLBCL) that has come back or stopped responding to prior treatment. **You may be eligible if...** - You are over 18 years old - You have confirmed DLBCL or a related large B-cell lymphoma that has relapsed or is refractory - You have received at least one prior line of therapy - You are not eligible for or have declined stem cell transplant - You have measurable disease and adequate organ function **You may NOT be eligible if...** - You have received prior tafasitamab or lenalidomide treatment - You have active or untreated brain involvement by lymphoma - You are pregnant or breastfeeding - You have significant heart, liver, or kidney dysfunction - You have an active serious infection or autoimmune condition Talk to your doctor to see if this trial is right for you.