Clinical Trial of TQB2825 Injection Combined Immunochemotherapy in Subjects With Diffuse Large B Cell Lymphoma

Inclusion Criteria: * Subjects voluntarily participate in this study, sign the informed consent form, and have good compliance; * Age 18 to under 80 years old (calculated from the date of signing the informed consent form); * Eastern Cooperative Oncology Group (ECOG) score of 0 to 2; * Life expectancy greater than 12 weeks; * In the dose expansion phase, previously untreated patients with International Prognostic Index (IPI) scores of 2-5; * A confirmed diagnosis of diffuse large B-cell lymphoma or grade 3b follicular lymphoma, in accordance with the 2022 World Health Organization (WHO) diagnostic criteria, based on histology or cytology (including diffuse large B-cell lymphoma-not otherwise specified and transformed from indolent lymphomas, not allowing for the following types or components: double-hit, triple-hit, or high-grade B-cell lymphoma-not otherwise specified, mediastinal large B-cell lymphoma, T/histiocyte-rich large B-cell lymphoma, human herpesvirus 8 (HHV8)-positive/primary effusion lymphoma, Anaplastic lymphoma kinase (ALK)-positive large B-cell lymphoma, Burkitt's lymphoma, and Hodgkin's lymphoma, etc.); * Immunophenotypic analysis shows that the tumor is CD20 positive; * Previous treatment meets the following criteria: 1. Combined with R-CHOP patients: previously untreated diffuse large B-cell lymphoma patients, allowing for corticosteroid pre-treatment (with or without vincristine) or non-curative palliative local radiotherapy. 2. Combined with GemOx patients: patients with diffuse large B-cell lymphoma who have received at least one line of systemic treatment (including at least one line with CD20 monoclonal antibody) and are not suitable for hematopoietic stem cell transplantation or have failed treatment after transplantation or relapsed, and whose disease progressed during the most recent treatment or relapsed after completion of treatment or confirmed no objective response after adequate treatment. * According to the 2014 Lugano criteria, there is at least one measurable lesion, i.e., lymph node lesions with a long diameter \>15 mm or extranodal lesions with a long diameter \>10 mm based on CT cross-sectional imaging; Positron emission tomography (PET)-computed tomography (CT) scan shows PET positivity; * Laboratory tests meet the following criteria (not corrected with blood transfusion or hematopoietic growth factors within 14 days before screening): 1. Hemoglobin (HGB) ≥80g/L; 2. Absolute neutrophil count (NEUT) ≥1.0×10∧9/L; 3. Platelet count (PLT) ≥ 75×10∧9/L (if accompanied by bone marrow invasion, platelets ≥50×10∧9/L). 4. Total bilirubin (TBIL) ≤ 1.5 times the upper limit of normal (ULN); 5. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 ULN. If accompanied by liver metastasis, then ALT and AST ≤ 5 ULN; 6. Serum creatinine (CR) ≤ 1.5 ULN or estimated glomerular filtration rate ≥50 ml/min by the Cockcroft-Gault formula. 7. Prothrombin time (PT), activated partial thromboplastin time (APTT), international normalized ratio (INR) ≤ 1.5×ULN (not on anticoagulant therapy); * Women of childbearing age must agree to use effective contraceptive measures during the study and for 12 months after the study ends, with a negative serum or urine pregnancy test within 7 days before study enrollment; men must agree to use effective contraceptive measures during the study and for 12 months after the study ends. Exclusion Criteria: * The subject has had or currently has other malignant tumors that occurred within 5 years before the first dose of the study drug. The following two situations are eligible for enrollment: other malignant tumors that have been treated with single surgery and have achieved continuous 5 years of disease-free survival (DFS); cured carcinoma in situ of the cervix, non-melanoma skin cancer, and superficial bladder tumors \[Ta (non-invasive tumors), Tis (carcinoma in situ), and T1 (tumors infiltrating the basement membrane)\]; * Adverse reactions from previous treatments have not recovered to a Common Terminology Criteria for Adverse Events (CTCAE) v5.0 grade score of ≤1, except for grade 2 alopecia, non-clinically significant and asymptomatic laboratory abnormalities, and hypothyroidism stabilized with hormone replacement therapy, which are deemed to have no safety risks by the investigator; * Received major surgical treatment, significant traumatic injury within 4 weeks before the first dose, or expected to undergo major surgery during the study treatment period, or has long-term unhealed wounds or fractures; * Any subject with bleeding or bleeding events ≥CTC AE grade 3 within 4 weeks before the first dose; * A history of arterial/venous thrombotic events within 6 months before the first dose, such as cerebrovascular accidents (including transient ischemic attacks), deep vein thrombosis, and pulmonary embolism, or any other history of serious thromboembolism (thrombosis from implanted venous access ports or catheters, or superficial vein thrombosis is not considered "serious" thromboembolism); * Clinically significant uncontrollable pleural effusion requiring repeated drainage, ascites, moderate or greater pericardial effusion; * Decompensated cirrhosis (Child-Pugh liver function rating of B or C) and active hepatitis (hepatitis B reference: positive HBsAg, and positive hepatitis B virus (HBV) DNA or detection value exceeding the lower limit of detection; hepatitis C reference: positive HCV antibody, and positive hepatitis C virus (HCV) RNA or detection value exceeding the lower limit of detection); Note: Subjects with hepatitis B who are positive for HBsAg, regardless of whether their HBV DNA is detectable, must continue antiviral treatment (nucleoside analogs recommended) and regularly monitor HBV DNA; for subjects with hepatitis B who are positive for HBcAb but negative for HBsAg, regular monitoring of HBV DNA is required, and prophylactic antiviral treatment is recommended; for hepatitis C subjects,