This study investigates the effects of adding an investigational medication to standard chemotherapy for patients with newly diagnosed stage II-IV diffuse large B cell lymphoma. Lymphoma is a type of cancer that begins in the lymphatic system, which is part of the body's immune system. The study aims to see how well the combination of rituximab and chemotherapy works with or without the investigational medication.

Participants will be randomly assigned to one of the study arms. One arm will receive rituximab and combination chemotherapy, while the other arm will receive the same treatment plus the investigational medication. The study will monitor the effects and outcomes of these treatments to assess their effectiveness and safety.

• Who can participate: Participants must be adults aged 18 years or older with a diagnosis of stage II-IV diffuse large B cell lymphoma. Additional eligibility criteria include adequate organ function and no prior treatment for lymphoma.
• Study details: Participants will be randomly assigned to receive either standard chemotherapy with rituximab or the same treatment plus an investigational medication. This study involves comparing the effects of these treatments.