The Outcomes of Systemic Chronic Active EBV Infection Treatment By Allogeneic Hematopoietic Stem Cell Transplantation: An Analysis of Japanese Registry Data

Background and aims

Systemic chronic active Epstein-Barr virus infection (sCAEBV) is classified as T- or NK-cell neoplasms in the WHO classification revised in 2017. Although allogeneic stem cell transplantation (allo-HSCT) is efficacious for sCAEBV, the effects are yet to be analyzed in a large number of cases due to the disease rarity. To investigate the outcomes and the prognostic factors of allo-HSCT in sCAEBV under the definition of the WHO 2017 classification, we analyzed retrospectively using the database of Japanese Society for Transplantation and Cellular Therapy (JSTCT).

Methods

Data collection

We used the clinical data of hematopoietic stem cell transplantation (HSCT) recipients of the Transplant Registry Unified Management Program (TRUMP) sponsored by JSTCT and Japanese Data Center for Hematopoietic Cell Transplantation (JDCHCT). Patients who underwent HSCT to cure EBV-associated diseases, secondary hemophagocytic lymphohistiocytosis (HLH), and virus-associated hemophagocytic syndrome between January 1993 and December 2016 were selected in TRUMP database, and on our behalf, JDCHCT sent out survey questions to the institutions of these patients to collect additional data to check if the diagnosis of sCAEBV matches our criteria, to analyze disease status at the time of HSCT, and to evaluate the efficacy of different treatment methods.

The diagnosis of sCAEBV

sCAEBV was diagnosed according to criteria suggested in 2016 by the Research group of Measures against Intractable Diseases by Ministry of Health, Labour and Welfare of Japan: (1) elevated EBV DNA load in peripheral blood (PB) (> 10 ^2.5 copies/μg DNA), (2) detection of EBV infection in T or NK cells from the affected tissues or PB, (3) systemic inflammatory symptoms such as fever, lymphadenopathy, liver dysfunction, progressive skin lesions, vasculitis, and uveitis persisting for > 3 months, and (4) exclusion of other possible diseases, such as primary EBV infection, autoimmune disease, immunodeficiencies, and lymphomas. Patients who fulfilled all (1) to (4) were diagnosed as sCAEBV. These criteria are compatible with the definition of sCAEBV described in the WHO definition of 2017.

The definitions of disease activities and responses

The disease activities are defined in previous reports (Blood. 2012;119, p673 and BMT. 2016;51, p879) as follows: positive of fever, ALT level elevation, vasculitis, progressive skin lesions, or uveitis. We defined the complete resolution of disease activity as complete response (CR) and CR with a significant decrease in PB EBV-DNA load (< 10 ^2.5 copies/μg DNA) as virological CR (vCR).

Results

81 patients who met the diagnostic criteria of sCAEBV were analyzed. The median age at HSCT was 24 years old, and the three-year overall survival rate (3-year OS) was 74.0%. Of 74 patients whose viral load after HSCT evaluated, 49 (66.2%) achieved vCR. The multivariate cox proportional hazard model revealed that advanced age, adolescent and young adult (AYA) (age, 15-39; n = 48) and adult (age, > 40; n = 13), was a risk factor of poor OS. The hazard ratios (HR) of AYA and adult groups were 10.14 and 4.63 respectively. It also showed that the presence of HLH at HSCT (HR 4.55), high sIL-2R (≥ median, 691 U/mL) at HSCT (HR 5.27), and conditioning without total body irradiation (HR 3.23) were independently associated with poor survival. Moreover, the median survival time of patients with active disease and extremely high sIL-2R level (≥ 3 × median, 2073 U/mL) was 0.9 months, whereas the other groups did not reach the median.

Conclusion

Although HSCT is the only curative treatment for sCAEBV, the strategies need improvements in high-risk cases, especially of high sIL-2R.