The purpose of this study is to evaluate the efficacy and safety of Sintilimab in combination with decitabine in the treatment of Relapsed/Refractory or advanced NK/T-cell lymphoma patients

Previous study has confirmed the efficacy of anti-PD-1 antibodies (including pembrolizumab or sintilimab). However, the CR rate of PD-1 antibody monotherapy is too low. Previous studies have demonstrated that decitabine may activate the T cells and enhance the efficacy of PD-1 antibodies in Hodgkin Lymphoma. Thus, the investigators aim to evaluate the efficacy and safety of sintilimab in combination with decitabine in the treatment of NK/T cell lymphoma.

Inclusion Criteria:

Histopathology and immunohistochemistry confirmed diagnosis of NK/Tcell lymphoma according to WHO 2016 criteria.

• refractory or relapsed after initial remission, or stage III-IV de novo patients
• PET/CT or CT/MRI with at least one objectively evaluable lesion.
• General status ECOG score 0-3 points.
• The laboratory test within 1 week before enrollment meets the following conditions: Blood routine: Hb>80g/L, PLT>50×10e9/L. Liver function: ALT, AST, TBIL ≤2 times the upper limit of normal. Renal function: Cr is normal. Cardiac function: LVEF≥50%, ECG does not suggest any acute myocardial infarction, arrhythmia or atrioventricular conduction above I Blocking.
• Sign the informed consent form

Exclusion Criteria:

Active infection requires ICU treatment. Concomitant HIV infection or active infection with HBV, HCV. Patients who are infected with HBV but not active hepatitis at the same time are notexcluded.

Significant organ dysfunction Pregnant and lactating women. Had a history of autoimmune diseases, and disease was active in the last 6 months.

Those who were known to be allergic to drugs in the study regimen. Patients with other tumors who require surgery or chemotherapy within 6 months.

• Other experimental drugs are being used.