High risk of relapsed disease in patients with NK/T cell chronic active Epstein-Barr virus disease outside of Asia.

Chronic active Epstein-Barr virus (EBV) disease (CAEBV) is characterized by high levels of EBV predominantly in T and/or NK cells with lymphoproliferation, organ failure due to infiltration of tissues with virus-infected cells, hemophagocytic lymphohistiocytosis (HLH) and/or lymphoma. The disease is more common in Asia than in the United States and Europe. While allogeneic hematopoietic stem cell transplantation (HSCT) is considered the only curative therapy for CAEBV, its efficacy and the best treatment modality to reduce disease severity prior to HSCT is unknown. Here, we retrospectively assessed an international cohort of 57 patients outside of Asia. Treatment for the disease varied widely, although most patients ultimately proceeded to HSCT. Though patients undergoing HSCT had better survival than those who did not (55% v 25%, p<0.01), there was still a high rate of death in both groups. Mortality was largely not affected by age, ethnicity, cell type involvement, or disease complications, but development of lymphoma showed a trend with increased mortality (56% v 35%, p=0.1). The overwhelming majority (75%) of patients who died after HSCT succumbed to relapsed disease. CAEBV remains challenging to treat when advanced disease is present. Outcomes would likely improve with better disease control strategies, earlier referral for HSCT, and close follow-up after HSCT including aggressive management of rising EBV DNA levels in the blood.