This is a clinical study on the efficacy and safety of low-dose CD20 monoclonal antibody injection in preemptive treatment of EBV positive lymphoproliferative diseases after allo-HSCT in patients with EBV-HLH and CAEBV

Purpose: To comprehend the efficacy and safety of low-dose CD20 monoclonal antibody injection in preemptive treatment of EBV positive lymphoproliferative diseases after allo-HSCT in patients with EBV-HLH and CAEBV Study subjects: PTLD patients undergoing allo-HSCT with CAEBV or EBV-HLH met the following conditions: (1) EBV-DNA (PBMC or plasma) > 1000 copies/ml in peripheral blood after transplantation; (2) no PTLD symptoms; (3) presence of aGVHD or clinicians believe that RI treatment is not suitable, or EBV-DNA persists > 1000 copies/ml after RI; (4) EBV infected lymphocytes; (4) B cell infection, or B cell copy number higher than other cell lines by 2 logs.

Therapeutic regimen: CD20 monoclonal antibody injection 100 mg/m2 was intravenously infused once a week. It can be discontinued after EBV-DNA negative for 2 consecutive times. Total dose≤ 4 applications per patient

Inclusion Criteria:

• PTLD patients undergoing allo-HSCT with CAEBV or EBV-HLH met the following conditions: (1) EBV-DNA (PBMC or plasma) > 1000 copies/ml in peripheral blood after transplantation; (2) no PTLD symptoms; (3) presence of aGVHD or clinicians believe that RI treatment is not suitable, or EBV-DNA persists > 1000 copies/ml after RI; (4) EBV infected lymphocytes; (4) B cell infection, or B cell copy number higher than other cell lines by 2 logs.

Exclusion Criteria:

• Patients with active infection except for EBV; Active hepatitis B or C (positive HBV-DNA or HCV-RNA) ; Known life-threatening allergic reactions to CD20 Monoclonal Antibody Injection or its preparation ingredients; Participate in other clinical studies.