Zanubrutinib, Lenalidomide and Rituximab (ZR2) in Elderly Treatment-naive Patients With Diffuse Large B-cell Lymphoma (DLBCL)

Inclusion Criteria: * Treatment-naive pathologically confirmed patients with diffuse large B-cell lymphoma (DLBCL) * Refuse to undergo systemic chemotherapy or not suitable for chemotherapy * Radiography detects measurable lesions defined as at least 1 clearly defined lesion/nodule with both long and short diameters longer than or equal to 1.5cm * Life expectancy of at least 3 months determined by researchers * The patient or his or her legal representative must provide written informed consent prior to any special examination or procedure for the research * Research drugs have not been used before Exclusion Criteria: * The patient has received systemic or local anti-tumor treatment, including chemotherapy, within three weeks before enrollment * The patient has complications of uncontrolled cardiovascular diseases, blood clotting disorders, connective tissue diseases, serious infectious diseases and other diseases * Laboratory measures meet the following criteria at screening (unless caused by lymphoma): 1. Neutrophils\<1.5 x 10\^9/L 2. Platelets\<80 x 10\^9/L 3. ALT or AST is 2 times higher than the normal upper limit, AKP and bilirubin are 1.5 times higher than normal upper limit 4. Creatinine is 1.5 times higher than the normal upper limit * Other concurrent and uncontrolled medical conditions that the researchers believe that they will affect the patient's participation in the study, including patients with psychosis or other known or suspected patients who cannot fully comply with the research protocol * HIV-infected patients * Patients with HbsAg positive are required to have negative HBV DNA before entering the group. In addition, if the patient is HBsAg negative but HBcAb positive (regardless of HBsAb status), HBV DNA test is also required, and if the result is positive, anti-viral treatment is also required, and negative HBV DNA is required before entering the group * Other medical conditions determined by the researchers that may affect the study