Combination therapy of therapeutic antibody and vaccine or entecavir in HBV carrier mice

HBsAg and TLR7/8 dual-targeting antibody-drug conjugates induce sustained anti-HBV activity in AAV/HBV mice: a preliminary study

Hepatitis B virus (HBV) infection is a significant global health concern due to elevated immunosuppressive viral antigen levels, the host immune system's inability to manage HBV, and the liver's immunosuppressive conditions. While immunotherapies utilizing broadly reactive HBV neutralizing antibodies present potential due to their antiviral capabilities and Fc-dependent vaccinal effects, they necessitate prolonged and frequent dosing to achieve optimal therapeutic outcomes. Toll-like receptor 7/8 (TLR7/8) agonists have been demonstrated promise for the cure of chronic hepatitis B, but their systemic use often leads to intense side effects. In this study, we introduced immune-stimulating antibody conjugates which consist of TLR7/8 agonists 1-[[4-(aminomethyl)phenyl]methyl]-2-butyl-imidazo[4,5-c]quinolin-4-amine (IMDQ) linked to an anti-hepatitis B surface antigen (HBsAg) antibody 129G1, and designated as 129G1-IMDQ. Our preliminary study highlights that 129G1-IMDQ can prompt robust and sustained anti-HBsAg specific reactions with short-term administration. This underscores the conjugate's potential as an effective strategy for HBsAg clearance and seroconversion, offering a fresh perspective for a practical therapeutic approach in the functional cure of CHB.

HIGHLIGHTS

HBV-neutralizing antibody 129G1 was linked with a TLR7/8 agonist small molecule compound IMDQ.Treatment with 129G1-IMDQ has shown significant promise in lowering HBsAg levels in AAV/HBV mice.129G1-IMDQ were eliciting a strong and lasting anti-HBsAg immune response after short-term treatment in AAV/HBV mice.

Preclinical animal models to evaluate therapeutic antiviral antibodies

Despite the availability of effective preventative vaccines and potent small-molecule antiviral drugs, effective non-toxic prophylactic and therapeutic measures are still lacking for many viruses. The use of monoclonal and polyclonal antibodies in an antiviral context could fill this gap and provide effective virus-specific medical interventions. In order to develop these therapeutic antibodies, preclinical animal models are of utmost importance. Due to the variability in viral pathogenesis, immunity and overall characteristics, the most representative animal model for human viral infection differs between virus species. Therefore, throughout the years researchers sought to find the ideal preclinical animal model for each virus. The most used animal models in preclinical research include rodents (mice, ferrets, …) and non-human primates (macaques, chimpanzee, ….). Currently, antibodies are tested for antiviral efficacy against a variety of viruses including different hepatitis viruses, human immunodeficiency virus (HIV), influenza viruses, respiratory syncytial virus (RSV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and rabies virus. This review provides an overview of the current knowledge about the preclinical animal models that are used for the evaluation of therapeutic antibodies for the abovementioned viruses.

New Treatment Options in Chronic Hepatitis B: How Close Are We to Cure?

Hepatitis B virus (HBV) infection is the leading cause of chronic liver disease worldwide. HBV-infected patients are at a lifetime risk of developing liver cirrhosis and hepatocellular carcinoma (HCC). Today, pegylated interferon (Peg-IFN) and nucleos(t)ide analogs (NAs) are used in the treatment of patients with chronic hepatitis B (CHB). Both treatment options have limitations. Despite effective viral suppression, NAs have little effect on covalently closed circular DNA (cccDNA), the stable episomal form of the HBV genome in hepatocytes. Therefore, the cure rate with NAs is low, and long-term treatment is required. Although the cure rate is better with Peg-IFN, it is difficult to tolerate due to drug side effects. Therefore, new treatment options are needed in the treatment of HBV infection. We can group new treatments under two headings: those that interfere with the viral life cycle and spread and those that modulate the immune response. Clinical studies show that combinations of treatments that directly target the viral life cycle and treatments that regulate the host immune system will be among the important treatment strategies in the future. As new direct-acting antiviral (DAA) and immunomodulatory therapies continue to emerge and evolve, functional cures in HBV treatment may be an achievable goal.