Remote Hepatitis B Infection (RHBI) is an immunological stage in the life cycle of Hepatitis B virus (HBV). It is characterized by the persistence of HBV DNA at low level within the liver or blood of people infected in past. As a result HBsAg, HBeAg and HBV DNA in serum are negative while Anti-HBs and/or Anti-HBc IgG are positive with normal liver enzymes. In Hematopoietic stem cell transplant (HSCT) patients, reactivation of RHBI leads to increased HBV replication and increased HBV DNA titres in blood and/or HBsAg or HBeAg positivity. There may be loss or gain of Anti-HBs and/or Anti-HBc IgG. The importance of recognizing this stage with a potential for reactivation is highlighted by the fact that: 1) HBV reactivation can lead to fulminant hepatitis & 2) Anti-HBV therapy such as lamivudine can prevent HBV reactivation. In this study we have aimed to determine the incidence of RHBI and HBV reactivation in our patients, the role of lamivudine in preventing HBV reactivation and the pattern of change in serological markers after reactivation.
All patients undergoing HSCT from March 2010 to May 2013 were included. Pre transplant, all patients were tested by ELISA for HBsAg, Anti-HBs, Anti-HBc IgM and Anti-HBc IgG. Post transplant, at the time of deranged liver function, all patients were tested for HBsAg, Anti-HBs, Anti-HBc IgM, Anti-HBc IgG, Anti-HCV, Anti-HEV and Anti-HAV. HBV DNA and HCV RNA were tested by polymerase chain reaction. RHBI was defined as positive Anti-HBc IgG and/or Anti-HBs (without history of HBV vaccination) with negative HBsAg and Anti-HBc IgM and normal liver function. HBV reactivation was defined as increase in transaminases to more than 3 times the upper limit of normal with HBV DNA and/or Anti-HBs and/or Anti-HBc IgG positivity (HBsAg and Anti-Hbc IgM being negative) at the time of deranged liver function. Lamivudine at a dose of 100 mg/d or 3 mg/kg/d (children <12 years) was given to all but one patient with Anti-HBc IgG positivity pre transplant irrespective of Anti-HBs positivity (Prophylaxis Group). Patients who had only Anti-HBs positivity did not receive prophylaxis (No Prophylaxis Group). Data was analyzed to explore the role of prophylactic lamivudine in preventing HBV reactivation and to determine the pattern of change of HBV serological markers at the time of reactivation. The time to respond to lamivudine was calculated as the interval from start of prophylaxis to normalization of liver enzymes.
Two hundred five patients underwent HSCT (autologous - 103 and allogeneic - 102) from March 2010 to May 2013. Twenty-eight (14%) patients were diagnosed to have RHBI (autologous-9, allogeneic-19). Thirteen patients did not receive prophylactic lamivudine (No-Prophylaxis Group) while 15 patients received prophylactic lamivudine (Prophylaxis Group). Twelve (92%) patients in No-Prophylaxis Group developed HBV reactivation while none (0%) in the Prophylaxis Group (P<0.001). The incidence of HBV reactivation was 10% (21 of 205 patients) which included 11 (52%) with only Anti-HBs positive, 1 with only Anti-HBc IgG positive and nine (43%) with all HBV serological markers negative (i.e. no evidence of RHBI) pre transplant. Six of these 9 patients sero-converted (5 - Anti-HBc IgG and 1 - Anti-HBs positive) at the time of reactivation. Seven (33%) developed HBV viremia at the time of HBV reactivation, of which 6 were Anti-HBs negative pre transplant. In contrast, of the patients with undetectable HBV DNA at the time of reactivation (14 patients), only 4(29%) were Anti-HBs negative pre transplant (P=0.0237). Seven (33%) patients were on steroids and 9(43%) were on cyclosporine at the time of reactivation. All patients responded to lamivudine within a median time of 17 days.
Incidence of RHBI in patients undergoing HSCT is high in our setting.
Lamivudine prophylaxis protects against HBV reactivation post transplant. We would recommend lamivudine prophylaxis in patients with RHBI with isolated Anti-HBs positivity in addition to those with Anti-HBc IgG positivity given the high rate of HBV reactivation in these patients.
All serological markers for Hepatitis B being negative pre transplant does not preclude HBV reactivation post transplant. Therefore, all serological markers for HBV should be repeated at the time of deranged liver functions post transplant.
Anti-HBs positivity pre transplant decreases the risk of HBV viremia at the time of reactivation.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.