This is a multicenter, randomized controlled, prospective clinical trial. The objective is to investigate the efficacy and safety of Tislelizumab maintenance therapy in newly diagnosed diffuse large B-cell lymphoma (DLBCL) patients after autologous hematopoietic stem cell transplantation (ASCT).

This is a multicenter, randomized controlled, prospective clinical trial. The objective is to investigate the efficacy and safety of Tislelizumab maintenance therapy in newly diagnosed diffuse large B-cell lymphoma (DLBCL) patients after autologous hematopoietic stem cell transplantation (ASCT). 94 patients were randomly divided into two groups according to the ratio of 1:1. The whole trial included screening period (day-28 to day-1), treatment period (Tislelizumab, 200mg every 8 weeks, 12 times) and follow-up period (2 years after the enrollment).

Inclusion Criteria:

1. Male and female, aged 18-65;

2. relapsed/refractory DLBCL patients after autologous stem cell transplantation;

3. Laboratory tests (blood tests, liver and renal function) meet the following requirements:

   1. Blood tests: white blood cell count ≥ 3.0 × 109 / L, absolute neutrophil count ≥ 1.5 × 109 / L, hemoglobin ≥ 90g / L, platelet ≥ 75 × 109 / L
   2. Liver function: transaminase ≤ 2.5 × upper limit of normal value, bilirubin ≤ 1.5 × upper limit of normal value;
   3. Renal function: serum creatinine 44-133 mmol / L;

4. The score of ECOG was 0-2;

5. The subject or his legal representative must provide written informed consent before the special examination or procedure of the study.

Exclusion Criteria:

1. Pregnant or lactating women;
2. Severe complications or infection;
3. Lymphoma involving central nervous system;
4. Participate in other clinical trials at the same time;
5. According to the judgment of the researcher, the patients who are not suitable for this study were selected.