Orelabrutinib, Sintilimab and Temozolomide in Relapsed or Refractory Central Nervous System Lymphoma

This study is testing a combination of three drugs — orelabrutinib, sintilimab (an immunotherapy), and temozolomide (chemotherapy) — for people whose lymphoma in the brain has come back or stopped responding to treatment. **You may be eligible if...** - You have been diagnosed with primary central nervous system (CNS) lymphoma or diffuse large B-cell lymphoma (DLBCL) that has spread only to the brain or spinal cord - Your lymphoma has returned or is not responding to prior treatment - You have received at least one prior treatment that included methotrexate - You are 18 years or older - You are able to follow the study schedule and complete required tests **You may NOT be eligible if...** - Your lymphoma has spread outside the brain and spinal cord - You have not previously received methotrexate-based treatment - You have serious medical conditions that would make participation unsafe - You are unable to provide informed consent Talk to your doctor to see if this trial is right for you.