To observe the safety, tolerability and clinical effects of PD-1 Antibody, Chidamide, Lenalidomide and Etoposide in Relapsed or Refractory NK/T cell Lymphoma.

This is a prospective, open-label, one-arm, multicenter clinical trial, aimed to evaluate the safety, tolerability, and efficacy of PD-1 Antibody, Chidamide, Lenalidomide and Etoposide in Relapsed or Refractory NK/T cell Lymphoma. A total of 50 patients are planned to be enrolled into the study. The primary end points are objective responder rate (ORR) and progression free survival(PFS) and the secondary end points include overall survival(OS) , and adverse events.

Inclusion Criteria:

1. age:14-65 years;Eastern Cooperative Oncology Group (ECOG)score≤2;expected survival≥3 months;
2. patients with NK/T Cell Lymphoma diagnosed by immuno-histochemistry (IHC) or fluorescence in situ hybridization (FISH);
3. Refractory or relapse after at least 2 regimen;
4. Once the patient received radiotherapy, need to be more than 3 months away from this treatment, and it is a non-primary recurrence;
5. No chemotherapy contraindications: hemoglobin ≥ 100g / L, absolute neutrophil count ≥ 1.5 × 109 / L, platelets ≥ 80 × 109 / L, ALT, AST ≤ 2 times the upper limit of normal, serum total bilirubin ≤ 1.5 times normal Upper limit, serum creatinine ≥ 1.5 times normal upper limit, serum protein ≥ 30g / L;
6. At least one measurable lesion;
7. There are no other serious diseases that conflict with this program, and the cardiopulmonary function is normal;
8. Women of childbearing age must have a negative urine or blood pregnancy test, and male patients should be contraceptive during medication;
9. There is no other antitumor treatment, but bisphosphonate for anti-bone metastasis treatment and other symptomatic treatment can be applied;
10. Can understand the situation of this study and sign the informed consent voluntarily

Exclusion Criteria:

1. rejecting providing blood preparation;
2. allergic to drug in this study or with hemophagocytic syndrome;
3. rejecting adopting reliable contraceptive method in pregnancy or lactation period;
4. uncontrolled internal medicine disease(including uncontrolled diabetes,severe incompetence cardiac,lung,liver and pancreas）；
5. with severe infection;
6. with primary or secondary central nervous system tumor invasion;
7. with Chemotherapy or radiotherapy contraindication;
8. ever suffered with malignant tumor;
9. Human immunodeficiency virus (HIV)-positive patients
10. Drug abuse or long-term alcohol abuse that affects the evaluation of test results;
11. Have peripheral nervous system disorder or mental disorder;
12. Patients with immune system diseases;
13. Those who have no legal capacity or whose research is affected by medical or ethical reasons;