Recurrence of HBV Reactivation after Allogeneic Hematopoietic Transplantation in Recipients with Resolved HBV Infection: A Nation-Wide Multicenter Retrospective Study
Authors: Onozawa Masahiro , Kusumoto Shigeru , Najima Yuho , Hashimoto Hiroya , Okada Kohei , Tamaki Masaharu , Tanaka Masatsugu , Sato Takayuki , Takahashi Tsutomu , Hatano Kaoru , Onodera Koichi , Moriuchi Yukiyoshi , Yakushijin Kimikazu , Kanda Junya , Nagafuji Koji , Ogata Masao , Nakano Nobuaki , Tamori Akihiro , Mizokami Masashi 
Published: December 2023

Introduction
Reactivation of hepatitis B virus (HBV) is known to cause fulminant hepatitis after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in recipients with resolved HBV infection. Monitoring of HBV-DNA and HBV-DNA-guided preemptive therapy using nucleotide analogue (NA) is recommended to prevent developing hepatitis due to HBV reactivation after allo-HSCT. However, little is known about the adequate duration of NA treatment and the frequency of the recurrence of HBV reactivation (2nd HBV reactivation) after discontinuation of NA. We conducted a nationwide retrospective study of HBV reactivation after allo- HSCT.
Patients and Methods
We retrospectively reviewed the clinical information of recipients with resolved HBV infection (HBsAg-negative, anti-HBc-positive) before allo-HSCT and were diagnosed as HBV reactivation (HBsAg and/or HBV-DNA positive) after allo-HSCT from January 2010 to December 2020. Patients who received prophylactic NA before HBV reactivation were excluded. This study was approved by the Hokkaido University Hospital institutional review boards and registered as UMIN 000046803.
Results
A total of 72 patients were enrolled (median age of 60 years, range, 27-73 years; 42 males and 30 females) from 16 institutions. Initial hematological diseases were acute myeloid leukemia 21, myelodysplastic syndrome 14, chronic myeloid leukemia 4, acute lymphoblastic leukemia 12, non-Hodgkin lymphoma 8, adult T cell leukemia-lymphoma 6, mixed phenotype acute leukemia 4, and others 3. HSCT details were as follows: donor source, unrelated bone marrow 33, cord blood 24, related peripheral blood 11, unrelated peripheral blood 4; acute graft versus host disease (GVHD) 48 (66.7%); chronic GVHD 44 (61.1%); systemic steroid usage 41 (56.9%). Initial HBV reactivation after allo-HSCT was observed on day 10-3034 (median 512.5). Immunosuppressants and systemic steroids were administered in 35 (48.6%) and 28 (38.9%) patients respectively at the time of HBV reactivation. The patients who showed anti-HBs below protection levels (&lt;10mIL/mL) were 18 (25%) of 72 patients at pre-HSCT, however, the number increased to 35 (81.4%) of 43 patients who were analyzed at the point of HBV reactivation after allo-HSCT. All patients received preemptive NA (entecavir 65, tenofovir alafenamide 6, tenofovir 1). Elevated aspartate transaminase of more than 200 U/L was observed in 7 cases at HBV reactivation, and all of them showed HBV-DNA more than 4 Log IU/mL. No one developed fulminant hepatitis but 5 patients resulted in continuous HBV carriers. Twenty-four of 72 patients were discontinued NA by each physician's decision. Of 24 patients who discontinued NA, 11 (45.8%) patients developed 2 nd HBV reactivation. The median duration from discontinuation of NA to 2 nd HBV reactivation was 113 days (range, 15 to 434). Duration of initial NA administration was not significantly different between patients with 2 ndHBV reactivation and those without 2 nd HBV reactivation (90-1968 days, median 553 vs 145-3734 days, median 861; p=0.11). In those who analyzed anti-HBs at discontinuation of NA, 4 of 8 cases (50.0%) with anti-HBs &lt;10 mIU/mL developed 2 nd HBV reactivation, whereas only 1 of 6 cases (16.7%) with anti-HBs &gt;10 mIU/mL developed 2 nd HBV reactivation. Four of the 11 cases with 2 nd HBV reactivation were attempted rechallenge of NA discontinuation, however, all 4 cases developed 3 rd HBV reactivation on day 28-127 after discontinuation of NA. These 4 cases further developed 4 th HBV reactivation after the rechallenge of discontinuation of NA. One patient developed protective anti-HBs titer after 2 courses of HB vaccination, and finally successfully discontinue the NA after 4 th HBV reactivation. The patient did not develop further reactivation for more than 3 years.
Conclusion
2 nd reactivation of HBV after NA discontinuation was common in patients with HBV reactivation who received allo-HSCT despite the long duration of NA. Acquisition of anti-HBs by HBV reactivation itself or HB vaccine would be necessary to suppress further HBV reactivation. Careful monitoring of HBV-DNA is important even after the discontinuation of NA in the case with HBV reactivation after allo-HSCT because multiple reactivations could occur. A prospective randomized trial of the HB vaccine after allo-HSCT for preventing HBV reactivation is now ongoing (UMIN000034113).