Hypofractionation Radiotherapy in Combination With Glofitamab in Relapsed/Refractory Diffuse B-cell Lymphoma With Baseline High Tumor Burden

Inclusion Criteria: * Signed informed consent. * Aged 18-75 years at the time of signing the informed consent, willing to follow and able to complete all study procedures. * Expected survival ≥ 12 weeks. * ECOG performance status score of 0-2 points ; * Patients with CD20-positive DLBCL confirmed by pathological histology; (unspecified DLBCL, HGBCL, PMBCL, FL-transformed DLBCL). * R/R DLBCL who have received at least one line of systemic treatment (including at least 2 cycles of rituximab-containing immunochemotherapy). * Baseline high tumor burden, defined as tumor diameter \> 6 cm and/or TMTV \> 128.7 mL . * HIV test results were negative at screening, except for the following: HIV-positive patients who have been receiving stable antiretroviral therapy and CD4 count ≥ 200/µL before enrollment Patients with undetectable viral load can be enrolled. * Women of childbearing age with negative urine or blood pregnancy test within 7 days before enrollment need to agree to take effective contraceptive measures during treatment and follow-up. Exclusion Criteria: * Individuals who have drug allergies or metabolic disorders to the drugs in this protocol. * Previous recipients of allogeneic organ transplants. * Individuals who received systemic immunotherapy within 4 weeks or 5 half-lives (whichever is shorter) of the drug. * Anti-cancer drug treatment within 28 days before the start of treatment * Prior radiotherapy in the mediastinum/pericardium area; radiation therapy for non-target lesion sites is allowed. * History of severe or extensive cardiovascular disease. * Recent major surgery (within 4 weeks before the start of Cycle 1), excluding diagnostic surgeries. * Currently suffering from active CNS lymphoma. * Known or suspected history of hemophagocytic lymphohistiocytosis (HLH) * Current or previous history of concurrent Waldenström's macroglobulinemia. * Known active infection at the time of enrollment in the study. * Immune-related adverse events that appeared during prior immunotherapy: ≥Grade 3 adverse events, except for Grade 3 endocrine diseases controlled by alternative therapies. Grade 1 or 2 adverse events that did not return to baseline levels after stopping treatment. * History of autoimmune diseases (long-standing or well-controlled autoimmune diseases, hypothyroidism, immune thrombocytopenic purpura, and well-controlled Type I diabetes are excluded). * Abnormal coagulation function: INR or PT \>1.5× upper limit of normal (ULN), PTT or aPTT \>1.5× ULN. * Suspected or latent tuberculosis (confirmed by positive IFNγ release test) * Active hepatitis B virus (HBV) infection/positive HCV RNA test for hepatitis C virus (HCV)/HIV seropositive. * Previously suffered from other invasive malignancies, excluding early-stage cervical cancer, basal cell carcinoma of the skin, and thyroid cancer . * Pregnant or breastfeeding, or planning to become pregnant during the study period or within 18 months after pre-treatment with obinutuzumab or within 2 months after the last dose of glofitamab (whichever is longer). * Other concurrent uncontrolled medical conditions that, in the investigator's opinion, would affect the patient's participation in the study.