Unrelated Cord Blood Transplantation for EBV-associated Lymphoproliferative Disorders

Inclusion Criteria:General Inclusion Criteria:

All subjects must meet all of the following criteria:

Age range: 14 to 80 years old, inclusive.

Diagnosed with an EBV-associated lymphoproliferative disease (including Chronic Active EBV Infection, EBV-associated Hemophagocytic Lymphohistiocytosis, and EBV-associated Lymphoma).

Meet at least one of the following disease-specific criteria (see below).

ECOG Performance Status score of 0-2 (or Lansky Play-Performance score ≥60 for children).

Expected survival of ≥3 months.

Signed informed consent form (for minors, consent must be provided by a legal guardian).

Disease-Specific Inclusion Criteria:

A. CAEBV Patients: Patients diagnosed with CAEBV according to the 2016 revised WHO classification criteria, who also meet all of the following:

* Persistent or recurrent infectious mononucleosis-like symptoms for more than 3 months.
* Elevated EBV-DNA load in peripheral blood or involved tissues (peripheral blood EBV-DNA \> 500 copies/ml).
* Detection of EBV in T or NK cells (via EBER in situ hybridization or LMP1 immunohistochemistry).
* Exclusion of other known immunodeficiency disorders, autoimmune diseases, or neoplastic diseases.

B. EBV-HLH Patients: Meet ≥5 of the HLH-2004 diagnostic criteria:

* Persistent or recurrent infectious mononucleosis-like symptoms for more than 3 months.
* Fever ≥38.5°C.
* Splenomegaly.
* Cytopenias (affecting ≥2 of 3 lineages):
* Hb \<90 g/L
* PLT \<100 × 10⁹/L
* ANC \<1.0 × 10⁹/L
* Hypertriglyceridemia (\>3 mmol/L) and/or hypofibrinogenemia (\<1.5 g/L).
* Serum ferritin \>500 μg/L.
* sCD25 \>2400 U/mL.
* Decreased or absent NK cell activity.
* Evidence of hemophagocytosis in bone marrow, spleen, or lymph nodes.

C. EBV-associated Lymphoma Patients:

* Pathologically confirmed diagnosis according to WHO criteria.
* EBV-positive (EBER+).
* Failure of or relapse after first-line therapy.

Exclusion Criteria:Patients meeting any of the following criteria will be excluded:

History of another primary malignancy within 5 years prior to the first treatment.

Uncorrected thyroid dysfunction.

Grade II or higher cardiac disease according to the New York Heart Association (NYHA) classification.

History of organ transplantation.

Planned to receive other types of hematopoietic stem cell transplantation during the study period.

Active infections, including:

Active hepatitis B or hepatitis C.

Positive serum HIV antigen or antibody.

History of syphilis.

Major surgery within 4 weeks prior to the first treatment, or anticipated need for major surgery during the study.

Pregnant or breastfeeding women.

History of severe psychiatric illness or substance abuse.

High risk of complications, such as:

Uncontrolled infection.

Active major visceral hemorrhage.

Known allergy to any component of the investigational drug(s), or a history of severe allergies.

Patients deemed unable to comply with the study procedures and/or follow-up requirements.

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