Toripalimab Combine With Rituximab for Treatment of Relapsed Refractory CD20 Positive Diffuse Large B-cell Lymphoma

Inclusion Criteria: 1. Age ≥18 years old; 2. According to the WHO 2016 classification criteria, the CD20 positive diffuse large B-cell lymphoma (DLBCL) diagnosed by pathology should include the indicators of immunohistochemistry: CD10, BCL-2, MUM-1, BCL-6 and C-MYC; 3. Relapsed or refractory DLBCL.Patients younger than 65 years should relapse or progress after receiving at least second-line treatment, and patients 65 years of age and older could be intolerant to second-line treatment, and they who relapse or progress after receiving first-line treatment; 4. There is at least one measurable lesion, defined as measurable dual-diameter, intra-lymph node lesion, short diameter\> 1.5cm, extra-lymph node lesion short diameter\> 1.0cm; 5. Recurrence confirmed by pathological biopsy and CD20 positive; 6. ECOG score 0-2 points; 7. No autoimmune diseases; 8. Blood routine examination meets the following criteria: 1. Neutrophil count ≥ 1.5 x 109 / L,; 2. Platelet ≥ 75 x 109 / L,; 3. Hemoglobin ≥ 10.0 g / dL; 9. The main organ function meets the following criteria: 1. Aspartate aminotransferase and alanine aminotransferase ≤ 2.0 times the upper limit of normal value; 2. Bilirubin ≤ 2.0 mg / dL; 3. Creatinine clearance rate ≥ 60 mL / min; 10. Patients must agree to take effective contraceptive measures during the study according to the investigator's request; 11. Understand and voluntarily sign written informed consent. Exclusion Criteria: 1. Diagnosed as transformed diffuse large B-cell lymphoma; 2. Diagnosed as double-hit diffuse large B-cell lymphoma (DHL); 3. Diagnosed as primary or secondary central nervous system lymphoma; 4. HBV DNA positive or HCV RNA positive patients; 5. Left ventricular ejection fraction \<50%; 6. Patients with history of autoimmune diseases, including but not limited to systemic lupus erythematosus, rheumatoid arthritis, Sjogren's syndrome, ankylosing spondylitis 7. Patients are using or have been used immunosuppressive drugs 8. Patients with ≥2 grade peripheral neuropathy