The HBsAg-HBcAg vaccine candidate was safe, well tolerated and immunogenic in this phase I study in healthy adults. To our knowledge, this is the first demonstration of safety and immunogenicity for a nasal vaccine candidate comprising HBV antigens.
Despite the existence of effective prophylactic vaccines, chronic hepatitis B remains a major public health problem, with more than 350 million people infected worldwide. Chronic infection increases the risk of serious liver diseases such as cirrhosis and hepatocellular carcinoma. Available therapies for chronic hepatitis B have limited efficacy and require long-term continuous treatments; that is why the development of therapeutic vaccines has been investigated as promising approach. In this sense, a novel vaccine formulation called ABX203 (HeberNasvac), based on the combination of the hepatitis B virus nucleocapsid and surface antigens, was developed. ABX203 has been studied in phase I, phase II and phase III clinical trial in treatment-naïve chronically infected patients in Bangladesh and in healthy volunteers in Cuba with promising results. In the present work we reviewed the main preclinical and clinical results of ABX203 development. Altogether, the data demonstrates safety and immunogenicity of ABX203 vaccine and support its use as a novel and competitive treatment alternative for chronic hepatitis B. The vaccine has been granted marketing authorization in Cuba.
The development of therapeutic vaccines against chronic hepatitis B requires the capacity of the formulation to subvert a tolerated immune response as well as the evaluation of histopathological damage resulting from the treatment. In the present study, the dynamicity of induced immune response to hepatitis B surface antigen (HBsAg) was evaluated in transgenic mice that constitutively express the HBsAg gene (HBsAg-tg mice). After immunization with a vaccine candidate containing both surface (HBsAg) and core (HBcAg) antigens of hepatitis B virus (HBV), the effect of vaccination on clearance of circulating HBsAg and the potential histological alterations were examined. Transgenic (tg) and non-transgenic (Ntg) mice were immunized by intranasal (IN) and subcutaneous (SC) routes simultaneously. A control group received phosphate-buffered saline (PBS) by IN route and aluminum by SC route. Positive responses, at both humoral and cellular levels, were obtained after five immunizations in HBsAg-tg mice. Such responses were delayed and of lower intensity in tg mice, compared to vaccinated Ntg mice. Serum IgG response was characterized by a similar IgG subclass pattern. Even when HBsAg-specific CD8+ T cell responses were clearly detectable by gamma-interferon ELISPOT assay, histopathological alterations were not detected in any organ, including the liver and kidneys.Our study demonstrated, that it is possible to subvert the immune tolerance against HBsAg in tg mice, opening a window for new studies to optimize the schedule, dose, and formulation to improve the immune response to the therapeutic vaccine candidate. These results can be considered a safety proof to support clinical developments for the formulation under study.How to cite this articleFreyre FM, Blanco A, Trujillo H, Hernández D, García D, Alba JS, Lopez M, Merino N, Lobaina Y, Aguilar JC. Dynamic of Immune Response induced in Hepatitis B Surface Antigen-transgenic Mice Immunized with a Novel Therapeutic Formulation. Euroasian J Hepato-Gastroenterol 2016;6(1):25-30.
Even after the exciting Phase I/II results, several companies have stopped studies with their candidates since they failed to fulfill specific clinical end points in subsequent trials. A closer look into these clinical results is required "
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