4CPS-104 Correlation between hyperimmune anti-hepatitis b immunoglobulin levels and clinical parameters in liver transplant recipients with HBV infection

<h3>Background and Importance</h3> Routine vaccination has reduced hepatitis B virus (HBV) incidence. However, the detection of cases, mostly imported, highlights the ongoing need for effective, safe, and up-to-date HBV treatments. <h3>Aim and Objectives</h3> This study evaluates the anti-hepatitis B immunoglobulin (HBIg) serum concentrations, in HBV-infected liver transplant patients, during induction and maintenance treatment after transplantation, and clinical and analytical factors that may influence their consistency. <h3>Material and Methods</h3> Ambispective, observational study included HBV-infected liver transplant patients on HBIg treatment from April 2018 to February 2024. Anthropometric, clinical, treatment (concomitant oral antivirals and immunosuppressive treatment) and analytical data were collected. Induction HBIg dose was 4000UI on day 1, 2000UI from day 2–7 and 1000–2000UI/month for maintenance. Therapeutic target range of HBIg concentrations during induction was 100–150UI/L(HBV-DNA negative) or &gt;500UI/L(HBV-DNA positive) and &gt;100UI/L during maintenance. <h3>Results</h3> Thirty patients (23/30[76.67%] men, 51.8(SD,12.65) years and 76.41(SD,11.41)kg) requiring liver transplantation for liver failure secondary to HBV infection were included. All patients received HBIg during induction (median, interval), 243.3UI/kg/month, 276.9–197.8) and maintenance (17.3UI/kg/month, 27.8–11.0) with pre-dose serum HBIg levels (mean, SD) of 234.2IU/L(328.9) and 326.7IU/L(261.5), respectively. The high inter-individual coefficient of variation(CV) observed −140.4% and 80.0%- results in 50% -in induction- and 29% -in maintenance- of the patients having mean values &lt;100 IU/L, including 21/29(72.4%) and 13/35(37.1%) of the individual values. Serum HBIg concentrations during induction and HBIg dose were not associated (P=0.434), although they were related during maintenance (P=0.007 and 74.4% of the variability explained). Recovery, expressed as UI/L HBIg per UI/kg/month administered, varied significantly between periods; P=0.004, and was 0.93(interval 3.78–0.09) and 17.14(26.31–3.81), respectively. Serum HBIg concentrations during induction and maintenance phases differ in magnitude but show no significant association with sex (mean M/F, 266.6/136.9-induction- and 385.7/303.1-maintenance-), pre-transplant HBIg levels (+/-, 99.4/458.7-induction- and 267.9/473.8-maintenance-), pre- (+/-, 123.6/271.0-induction- and 212.0/372.6-maintenance-) or post-transplant viral load (+/-, 70.4/257.6-induction- and 58.6/371.4-maintenance-), HDV status (+/-, 390.2/92.2-induction- and 443.3/169.8-maintenance-), or the antiviral used (entecavir/tenofovir, 138.8/291.4-induction- and 539.1/241.8-maintenance-). There was no association with weight, height or BMI. <h3>Conclusion and Relevance</h3> Serum HBIg concentrations and recovery showed significant inter-individual variability, making regular monitoring essential. Moreover, low HBIg concentrations during induction suggest the need for higher doses to reach the therapeutic range and ensure immunisation against HBV. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest