This study aimed to investigate the efficacy and safety of L-DEP (L-Asparaginasum, liposomal doxorubicin, etoposide and methylprednisolone) together with PD-1 antibody as an treatment for relapse/refractory EBV associated hemophagocytic lymphohistiocytosis.

PD-1 antibody added to the DEP regimen （with or without asparaginases） in EBV-HLH

Inclusion Criteria:

1. Meet hemophagocytic lymphohistiocytosis (HLH)-04 diagnostic criteria;patients were diagnosed with EBV associated HLH (EBV-HLH).
2. EBV-DNA in peripheral blood or EBER in tissue were positive.
3. Treated with HLH-94 no less than 2 weeks before enrollment and did not achieve at least partial response
4. The patient is expected to be unable to undergo allogeneic hematopoietic stem cell transplantation in the short term due to various reasons (physical status, economic reasons, donor reasons, etc.)
5. The expected survival time is more than 1 month.
6. Age ≤ years old, gender is not limited.
7. Serum creatinine ≤ 1.5 times normal；After infusion, fibrinogen can be corrected to ≥0.6g/L.
8. Serum human immunodeficiency virus(HIV) antigen or antibody negative； Hepatitis C virus (HCV) antibody is negative, or HCV antibody is positive, but HCV RNA is negative；HBV copies less than 1E+03 copies/ml.
9. The left ventricular ejection fraction (LVEF) was normal.
10. No uncontrollable infection.
11. Contraception for both male or female.
12. Informed consent obtained.

Exclusion Criteria:

1. Allergic to doxorubicin and/or etoposide and/or PD-1 antibody Injection
2. Severe myocardial injury, myocardial enzymes CK, CK-MB increased more than 3 times ULN (upper limit of normal)
3. Heart function above grade II (NYHA).
4. Thyroid dysfunction
5. Serious mental illness;
6. Active hemorrhage of internal organs
7. Previously received L-DEP regimen for HLH-targeted treatment, but the treatment was ineffective or relapsed
8. Accumulated dose of doxorubicin above 300mg/m2 or epirubicin above 450mg/m2
9. Participate in other clinical research at the same time.