Hepatitis B in liver transplant recipients

Passive Monoclonal and Polyclonal Antibody Therapies

Passive antibody therapies have a long history of use. In the 19th century, antibodies from xenographic sources of polyclonal antibodies were used to treat infections (diphtheria). They were used often as protection from infectious agents and toxins. Complications related to their use involved development of immune complexes and severe allergic reactions. As a result, human source plasma for polyclonal antibodies became the preferential source for antibodies. They are used to treat infection, remove toxins, prevent hemolytic disease of the newborn, modify inflammatory reactions, and control autoimmune diseases. Continued improvements in processing decreased the transfusion/infusion transmission of infections. In the late 20th century (∼1986), monoclonal antibodies were developed. The first monoclonal antibodies were of xenographic source and were wrought with problems of immunogenicity. These forms of antibodies did not gain favor until chimerization took pace in the mid-1990s and in 1998 two monoclonal antibodies were approved one to treat respiratory syncytial virus and the other for breast cancers. Further development of humanized and then fully human monoclonal antibodies has led to an evolution of therapies with these agents. Monoclonal antibodies are being researched or approved to treat a multitude of diseases to include oncologic, inflammatory, autoimmune, cardiovascular, respiratory, neurologic, allergic, benign hematologic, infections, orthopedic, coagulopathy, metabolic and to decrease morbidity of disease (diminution of pain), modify disease progression, and potentially anatomic development. In this chapter, we will review the history of use of these passive antibody therapies, their mechanism of action, pharmacologic-therapeutic classification, particular medical indication, adverse reactions, and potential future use of these medications.

Reactivation of hepatitis B after liver transplantation: Current knowledge, molecular mechanisms and implications in management

Chronic hepatitis B (CHB) is a major global health problem affecting an estimated 350 million people with more than 786000 individuals dying annually due to complications, such as cirrhosis, liver failure and hepatocellular carcinoma (HCC). Liver transplantation (LT) is considered gold standard for treatment of hepatitis B virus (HBV)-related liver failure and HCC. However, post-transplant viral reactivation can be detrimental to allograft function, leading to poor survival. Prophylaxis with high-dose hepatitis B immunoglobulin (HBIG) and anti-viral drugs have achieved remarkable progress in LT by suppressing viral replication and improving long-term survival. The combination of lamivudine (LAM) plus HBIG has been for many years the most widely used. However, life-long HBIG use is both cumbersome and costly, whereas long-term use of LAM results in resistant virus. Recently, in an effort to develop HBIG-free protocols, high potency nucleos(t)ide analogues, such as Entecavir or Tenofovir, have been tried either as monotherapy or in combination with low-dose HBIG with excellent results. Current focus is on novel antiviral targets, especially for covalently closed circular DNA (cccDNA), in an effort to eradicate HBV infection instead of viral suppression. However, there are several other molecular mechanisms through which HBV may reactivate and need equal attention. The purpose of this review is to address post-LT HBV reactivation, its risk factors, underlying molecular mechanisms, and recent advancements and future of anti-viral therapy.

Tenofovir-emtricitabine therapy for the prevention of hepatitis B recurrence in four patients after liver transplantation

In patients infected with chronic hepatitis B virus (HBV) that goes untreated, therapeutic options are limited once the disease decompensates, and orthotopic liver transplantation is often the only treatment available to save the patient's life. After liver transplantation, combined therapy with hepatitis B immune globulin (HBIG) and a nucleos(t)ide analog is the standard of practice for the prevention of HBV recurrence. Historically, nucleos(t)ide analogs such as lamivudine and adefovir have been used with low-dose HBIG for the prevention of HBV recurrence after liver transplantation. However, these analogs are ineffective when used alone due the emergence of resistance mutations. Newer nucleos(t)ide analogs such as tenofovir disoproxil fumarate have demonstrated higher resistance thresholds and effective viral suppression when paired with low-dose HBIG. In this case series, we evaluated the safety and efficacy of switching four patients from low-dose HBIG plus nucleos(t)ide analog therapy for the prevention of HBV recurrence to a combination tenofovir-emtricitabine regimen. At the end of follow-up, all patients remained hepatitis B surface antigen negative and had HBV DNA levels of less than 10 IU/ml. Additionally, no tenofovir-associated nephrotoxicity was observed among the four patients. Tenofovir-emtricitabine monotherapy in lieu of HBIG plus nucleos(t)ide analog therapy demonstrated prevention of HBV recurrence without tenofovir-associated nephrotoxicity after 9 months of follow-up in all four patients and up to 15 months in one patient.

Current status of liver transplantation for hepatitis B virus

The management of hepatitis B in liver transplantation has evolved significantly over the past 2 decades. Introduction of hepatitis B immune globulin and subsequently nucleos(t)ide analogues has revolutionized transplantation for hepatitis B virus (HBV), increasing survival for patients transplanted for this indication. With the availability of new and potent antivirals for HBV, the need for liver transplant should continue to decrease in the coming years. Moreover, the newer antivirals with high resistance barriers will allow effective long-term viral prophylaxis and therefore, prevention of recurrence.

Posttransplantation prophylaxis with primary high-dose hepatitis B immunoglobulin monotherapy and complementary preemptive antiviral add-on

A considerable proportion of liver transplantation recipients who receive hepatitis B immunoglobulin (HBIG) monotherapy for hepatitis B virus (HBV) prophylaxis develop resistance to HBIG. We retrospectively assessed the efficacy of HBV prophylaxis in 1524 patients who received primary high-dose HBIG monotherapy (n = 1463) or with a preemptive antiviral add-on as secondary combination therapy (n = 61). At a median follow-up time of 57 months, 106 (7.3%) patients receiving HBIG monotherapy experienced HBV recurrence, with a 10-year HBV recurrence rate of 9.8%, compared to none of the patients receiving preemptive combination therapy (P = 0.047). Thirteen patients (12.3%) with HBV recurrence failed antiviral therapy, leading to death or retransplantation. Response rates to rescue therapy before and after use of adefovir/entecavir were 44.4% and 91.8%, respectively. Acute exacerbation was not associated with treatment failure, but required prolonged treatment. Of 84 surviving patients with HBV recurrence, 44 (52.4%) showed no evidence of blood HBV DNA. The Gly145Arg mutation was found in 11 of 15 (73.3%) patients, whereas 25 of 71 (35.2%), 2 of 29 (6.9%), and 4 of 8 (50%) patients were resistant to lamivudine, adefovir, and entecavir, respectively. In conclusion, our finding of a 10-year HBV recurrence rate of 9.8% in patients receiving high-dose HBIG monotherapy indicates that this treatment is effective but requires complementary measures. Strict surveillance following HBIG monotherapy is necessary to enhance responses to rescue antiviral therapy. Preemptive conversion to combination therapy has a complementary role in prophylaxis with primary high-dose HBIG monotherapy, especially for patients at high risk of HBV recurrence.

Liver grafts from anti-hepatitis B core positive donors: a systematic review

BACKGROUND & AIMS

Although hepatitis B virus (HBV) transmission after liver transplantation of grafts from HBsAg-negative, anti-HBc positive donors is well established, the growing organ shortage favours the use of such marginal grafts. We systematically evaluated the risk of HBV infection after liver transplantation with such grafts and the effect of anti-HBV prophylaxis.

METHODS

We performed a literature review over the last 15 years identifying 39 studies including 903 recipients of anti-HBc positive liver grafts.

RESULTS

Recurrent HBV infection developed in 11% of HBsAg-positive liver transplant recipients of anti-HBc positive grafts, while survival was similar (67-100%) to HBsAg-positive recipients of anti-HBc negative grafts. De novo HBV infection developed in 19% of HBsAg-negative recipients being less frequent in anti-HBc/anti-HBs positive than HBV naive cases without prophylaxis (15% vs 48%, p<0.001). Anti-HBV prophylaxis reduced de novo infection rates in both anti-HBc/anti-HBs positive (3%) and HBV naive recipients (12%). De novo infection rates were 19%, 2.6% and 2.8% in HBsAg-negative recipients under hepatitis B immunoglobulin, lamivudine and their combination, respectively.

CONCLUSIONS

Liver grafts from anti-HBc positive donors can be safely used, preferentially in HBsAg-positive or anti-HBc/anti-HBs positive recipients. HBsAg-negative recipients should receive prophylaxis with lamivudine, while both anti-HBc and anti-HBs positive recipients may need no prophylaxis at all.

Decision analysis model for hepatitis B prophylaxis one year after liver transplantation

In patients receiving orthotopic liver transplantation, hepatitis B recurrence rates have decreased significantly with the use of various methods for prophylaxis. At present, a combination of hepatitis B immunoglobulin (HBIG) and lamivudine is the standard of care, resulting in recurrence rates of 0% to 11%. Recent data suggest that the addition of adefovir to lamivudine is successful in treating patients with recurrent hepatitis B infection. A Markov model was used to compare costs and outcomes of 2 strategies for hepatitis B prophylaxis 1 year after transplantation. The first consisted of prophylaxis with lamivudine and adefovir (strategy 1), whereas the second consisted of intramuscular HBIG and lamivudine (strategy 2) with the addition of adefovir in patients who subsequently developed hepatitis B recurrence. Patients who failed with adefovir and lamivudine were then treated with tenofovir and entecavir. 16.8% of liver transplant recipients had hepatitis B recurrence after 10 years of treatment with lamivudine and HBIG. The medical costs for strategy 1 and strategy 2 after 10 years of therapy were $151,819 and $166,246, respectively, and this resulted in cost savings of $14,427. The decision analysis model began 1 year after liver transplantation. A 1-way sensitivity analysis demonstrated that the model was most sensitive to cost changes of adefovir and HBIG injections as well as variations in the hepatitis B virus recurrence rate. The model was robust to costs of lamivudine, laboratory costs, administrative fees, and office visit fees. Our decision analysis model resulted in marked savings in costs with strategy 1 (lamivudine and adefovir), providing pharmacoeconomic support for the use of this strategy as first-line therapy in hepatitis B prophylaxis in liver transplant recipients 1 year after liver transplantation.

Dysfunction of splenic macrophages in cirrhotic patients with hypersplenism and HBV infection

BACKGROUND

Hepatitis B virus (HBV) reinfection is a difficult problem to manage after liver transplantation in patients with cirrhosis. This study was designed to investigate the activation type of splenic macrophages in cirrhotic patients with hypersplenism and HBV infection to assess the immune function of splenic macrophages.

METHODS

Fourteen cirrhotic patients with hypersplenism and HBV infection and 6 controls were enrolled in the study. Serum lipopolysaccharide (LPS) was detected with a limulus assay. The differential expression of cytokines by splenic tissue and splenic macrophages between the cirrhosis and control groups was compared with cytokine arrays. Furthermore, splenic macrophages were cultured and stimulated with LPS, after which tumor necrosis factor (TNF)-alpha and interleukin (IL)-12 levels in the supernatant were determined.

RESULTS

In cirrhotic patients, serum LPS levels increased significantly. Interferon-gamma, TNF-beta, and transforming growth factor-beta upregulated, whereas IL-4 and IL-13 levels did not change in splenic tissue. TNF-alpha upregulated significantly, whereas IL-4 and IL-5 levels had no significant changes in splenic macrophages. The IL-12 levels in culture media of splenic macrophages from cirrhotic patients were significantly lower than in controls after LPS stimulation.

CONCLUSION

Splenic macrophages may be activated via incomplete M1 activation in cirrhotic patients with hypersplenism and HBV infection, and the immune function of splenic macrophages is impaired.

Exploring the native human antibody repertoire to create antiviral therapeutics

Native human antibodies are defined as those that arise naturally as the result of the functioning of an intact human immune system. The utility of native antibodies for the treatment of human viral diseases has been established through experience with hyperimmune human globulins. Native antibodies, as a class, differ in some respects from those obtained by recombinant library methods (phage or transgenic mouse) and possess distinct properties that may make them ideal therapeutics for human viral diseases. Methods for cloning native human antibodies have been beset by technical problems, yet many antibodies specific for viral antigens have been cloned. In the present review, we discuss native human antibodies and ongoing improvements in cloning methods that should facilitate the creation of novel, potent antiviral therapeutics obtained from the native human antibody repertoire.

Current concepts in the evaluation of patients for liver transplantation

Candidates for liver transplantation undergo a thorough medical, surgical, psychosocial and financial evaluation prior to listing for transplantation. Prioritization for allocating livers is based upon the model for end-stage liver disease score and waiting-time mortality with the fundamental concept of giving organs to the sickest first. In the upcoming years the allocation system may be modified to include other factors associated with mortality, such as serum sodium, and may incorporate both pre- and post-transplant mortality. Strategies to expand the donor pool include utilizing livers from donors after cardiac death, split liver transplantation and living donor liver transplantation. Future challenges for liver transplantation will include the obesity epidemic and the prevention and treatment of recurrent disease, particularly hepatitis C.