This study tests a treatment for a type of blood cancer called **diffuse large B-cell lymphoma (DLBCL)**. The treatment combines three drugs: *glofitamab*, *gemcitabine*, and *oxaliplatin*. Researchers want to see if this treatment is safe and works well for people whose cancer has come back or didn't respond to treatment. To join the study, patients must have a certain type of DLBCL and have tried at least one other treatment before. They cannot join if they have certain other health problems or if they've had some specific treatments in the past. **Key Points:** - The study involves taking medications and regular check-ups. - Participants cannot have recent major infections or certain health issues. - The study aims to include people from different racial and ethnic backgrounds in the U.S. It's important for patients to consider their health conditions and past treatments to see if this study is suitable for them.