Patients with relapsed/refractory diffuse large B cell lymphoma with extranodal (esp. central nervous system) involvement treated with Low-Dose Decitabine plus anti-PD-1 regimen. 3 weeks for a cycle, with a total of 2 years or until the disease progress esor unacceptable toxicity occurs, or the patient decides to withdraw from the trial.

To evaluate the effectiveness and safety of patients with relapsed/refractory diffuse large B cell lymphoma with extranodal (esp. central nervous system) involvement treated with Low-Dose Decitabine plus anti-PD-1 regimen. 3 weeks for a cycle, with a total of 2 years or until the disease progress esor unacceptable toxicity occurs, or the patient decides to withdraw from the trial. Enrollment was planned to be completed within 2 years, and all trials were followed up for 12 months after the last enrolled patient completed treatment. All cases will be followed up and the long-term curative effect will be observed and recorded.

Inclusion Criteria:

• 14-80 years old, male or female;
• Pathologically confirmed relapsed/refractory diffuse large B cell lymphoma with extranodal (central nervous system) involvement;
• Expected survival of more than 3 months;
• AST and ALT ≤ 3.0 ULN; TBIL and CCr ≤ 1.0 ULN;
• Inactive infection and severe mental illness
• ECOG score 0~2
• According to the New York Heart Association (NYHA) cardiac function grading standards, the heart function grading should be grade I or Grade II; Cardiac ejection fraction >50% or not lower than the lower limit of the range of laboratory test values at the study center; No pathological abnormality was found in ECG; There was no clinically significant pericardial effusion or pleural effusion
• The serum pregnancy test of female subjects must be negative
• Signed informed consent

Exclusion Criteria:

• Subjects with any autoimmune disease requiring long-term use of corticosteroids or immunosuppressive drugs or with a history of other tumors;
• Severe uncontrolled medical disease or active infection (including HIV+);
• Active gastrointestinal bleeding or 1 month history of gastrointestinal bleeding;
• Received allogeneic hematopoietic stem cell transplantation within 6 months or are participating in other clinical studies;
• Pregnant or nursing women;
• Subjects who must be forcibly detained for the treatment of mental or physical diseases (e.g. infectious diseases);
• The researcher thinks it is not suitable for this clinical study (such as poor compliance, drug abuse, etc.)
• The situation that the researcher judged was not suitable for inclusion

Low-Dose Decitabine plus anti-PD-1 treatment for relapsed/refractory diffuse large B cell lymphoma with extranodal (dsp. central nervous system) involvement: A phaseⅡclinical trial