Title: Nucleos(t)ide withdrawal in HBeAg negative hepatitis B virus infection to promote HBsAg clearance. (NUC-B)
Funder: Medical Research Council

Abstract: Hepatitis B virus (HBV) causes infection of the liver, either a severe infection with a shorter duration (acute) or a persistent longer term infection (chronic). Chronic infection leads to cirrhosis and liver failure or to liver cancer in approximately 25% of cases. Worldwide there are 350 million people with chronic HBV infection and the virus is responsible for over 1 million deaths per year. Two types of treatment for chronic HBV infection are available: interferons or nucleoside/nucleotide analogues. Interferons are used for a finite period of time (3 to 12 months). Treatment with interferon can rarely result in elimination of the virus; ie a cure. In up to 30% of patients interferon helps the patient’s immune system to gain control of the infection so that they have a low level of HBV in their body and can safely stop taking treatment with no further damage to their liver (known as a sustained virological response). Interferons have to be given by injection and cause unpleasant side effects and if interferon fails patients have to be treated with nucleos(t)ide analogues. This, combined with a success rate of only 30%, means the majority of patients choose to be treated instead with nucleos(t)ide analogues._x000D_ Nucleos(t)ide analogues are drugs that work by stopping the virus replicating in the body so after treatment the virus is no longer detectable in the blood and the progression of liver disease is prevented or even reversed in virtually all patients. Nucleos(t)ide analogues are tablets which are taken every day and cause no side effects, however, once started the majority of patients will need to continue taking them for the rest of their life._x000D_ A recent clinical trial in Greece has shown that if treatment with nucleos(t)ide analogues is stopped after 4–5 years patients experience a worsening of liver inflammation (hepatitis) – known as a hepatitis flare - as the virus starts to replicate again. However, in some of these patients the hepatitis flare led to elimination of the virus presumably due to the body having been able to recover its ability to fight the virus whilst on treatment. Elimination of the virus is important because it represents a cure of infection so that all treatment and medical follow up can be safely discontinued._x000D_ In the proposed study we plan to confirm the findings of the Greek trial. In addition we propose to use interferon in some of the patients at the time that the nucleos(t)ide analogue treatment is withdrawn in order to increase the immune response against the virus. After all treatments are withdrawn we will follow the patients for at least three years to determine whether they eliminate the virus. It is expected that some patients will experience a severe flare in their hepatitis which will require reintroduction of their nucleos(t)ide analogue therapy so we will follow all patients frequently._x000D_ We anticipate three outcomes for the patients in the trial. 1. They might achieve viral elimination (a cure), 2 They might achieve a sustained virological response (their immune system can keep the virus at a low level) or 3. They might relapse and require resumption of their nucleos(t)ide analogues. In the future it will be important to be able to predict which patients end up with which outcome so as part of this trial we will measure a number of variables by testing samples from the patients liver and blood to predict which patients are most likely to benefit from which treatment.

Lay abstract: Chronic infection with hepatitis B virus causes death through decompensated cirrhosis or hepatocellular carcinoma in over a million people per year. Treatment is available to prevent progression to end stage liver disease either by induction of immune responses during finite therapy with type I interferon or by suppressing viral replication using nucleos(t)ide` analogues (1,2). The majority of patients in the UK have the HBeAg negative form of infection and are treated with nucleos(t)ide analogues but cure of the infection, indicated by loss of HBV surface antigen (HBsAg), occurs in less than 2% of cases so the majority remain indefinitely on treatment (3). A study in HBeAg negative patients investigated the effect of treatment withdrawal after 4-5 years of nucelos(t)ide analogues and found that 30% of patients lost HBsAg during 4 years of follow up and a further 30% remained stable with low viral load and normal liver function off treatment (7). The primary aim of the proposed study is to demonstrate that this outcome can be replicated in a larger and more diverse group of HBV infected patients. _x000D_ Loss of HBsAg in patients with chronic HBV infection requires immune-mediated clearance of the HBV minichromosome (cccDNA) from infected hepatocytes. Innate and adaptive immune responses are impaired in chronic HBV infection. High level viral replication and an attenuated endogenous interferon response have been implicated in the HBV-specific immune paresis but partial restoration of immune responses have been observed after long term viral suppression (9, 10). Interferon is used clinically to promote innate and adaptive immune responses against HBV. Although combining pegylated interferon with nucleos(t)ide analogues as initial treatment does not improve clinical outcomes, there is a strong immunological rationale for using interferon as sequential therapy after viral replication has been suppressed and some adaptive immunity restored. This has been validated in HBeAg positive patients(15). Unlike nucleos(t)ide analogues interferons activate intracellular cytadine deaminases which promote cccDNA degradation (12). The second aim of the proposed study is therefore to explore whether adding a short course of pegylated interferon therapy prior to complete treatment cessation would increase the proportion of patients achieving HBsAg loss. _x000D_ It is clearly important to understand the mechanisms associated with HBsAg loss so the third aim of the study will be to measure HBV specific immune responses and NK cell responses at multiple timepoints during the trial to identify correlates of viral elimination. In a subset of patients who consent to repeated fine needle aspirates of the liver we will explore immune response in more detail by analysing the phenotype and function of intrahepatic lymphocytes using state-of-the-art FACS techniques._x000D_ Finally we will try to identify from baseline parameters which patients are most likely to achieve HBsAg loss. Serum HBsAg concentrations, intrahepatic cccDNA levels, viral genotype, immunological parameters and demographic variables will be explored as predictors of successful clinical outcomes. _x000D_ HBsAg loss is important to the NHS as it allows patients to be discharged from clinic without requirement for indefinite antiviral therapy.

Research activity codes: 5.1 PHARMACEUTICALS;6.1 PHARMACEUTICALS
Health categories: INFECTION