RESUMEN
HeberNasvac is a recently developed therapeutic vaccine for chronic hepatitis B (CHB) administered by intranasal (IN) and subcutaneous (SC) routes in a 14 days/10 doses schedule. To compare different schedules and routes of immunizations, a group of patients received four different vaccination regimens in a placebo-controlled factorial study. Subsequently, patients were followed for a minimum time of 48 weeks. Samples collected at the end of the follow-up were compared with initial samples. Groups I and II received the product by IN/SC routes, every 14 and 7 days, respectively. Groups III and IV were treated by SC route alone following a 14 and 7 days schedule. A group of 21 CHB patients received the vaccine in four different schedules and eight patients received placebo for a total of 29 patients enrolled. The 61.9% of vaccinees reduced their VL ≥2Log compared with baseline levels and 25% in placebo group. The 47.6% of vaccines reduced HBV levels to undetectable, 25% in placebo. HBeAg loss and seroconversion to anti-HBeAg was only achieved in vaccinees, 4 out of 9 (44.4%), and 40% (8 out of 20) developed anti-HBs response, none in placebo group. Reduction of HBsAg level in ≥1Log was achieved in the 35.0% of vaccinees and in none of the placebo-treated patients. Considering the individual and factorial analysis, significant HBV DNA reduction was detected in groups I and II, immunized by IN/SC routes. A significantly higher proportion of patients reducing VL to ≥2Log was also detected grouping the patients treated by IN/SC routes (G I + II) and grouping those inoculated every 14 days (G I + III), with 72.7% and 63.6%, respectively, compared with the placebo group (25.0%). The patients immunized every 14 days (G I + G III) also reduced the HBsAg levels compared with baseline. In conclusion, after more than 48 weeks of treatment-free follow-up, HeberNasvac-treated patients demonstrated superior responses compared with the placebo group in terms of antiviral and serological responses. The factorial analysis evidenced that the schedule combining the IN route of immunization and the frequency of 14 days resulted in the stronger antiviral and serological responses. Present results support the study of IN-only immunization schedules in future and was consistent with previous results. Long-lasting follow-ups were done to explore histological variables and the progression of serological variables in order to detect late responders. How to cite this article: Freyre FM, Aguiar JA, Cinza Z, et al. Impact of the Route and Schedule of Immunization on the Serological and Virological Response of Chronic Hepatitis B Patients Treated with HeberNasvac. Euroasian J Hepato-Gastroenterol 2023;13(2):73-78.
RESUMEN
Nasvac (HeberNasvac®) is a novel therapeutic vaccine for chronic hepatitis B (CHB). This product is a formulation of the core (HBcAg) and surface (HBsAg) antigens of the hepatitis B virus (HBV), administered by nasal and subcutaneous routes, in a distinctive schedule of immunizations. In the present review article, we discuss the action mechanisms of HeberNasvac, considering the immunological properties of the product and their antigens. Specifically, we discuss the capacity of HBcAg to activate different pathways of innate immunity and the signal transduction after a multi-TLR agonist effect, and we review the results of recent clinical trials and in vitro studies. Aimed at understanding the clinical results of Nasvac and other therapeutic vaccines under development, we discuss the rationale of administering a therapeutic vaccine through the nasal route and also the current alternatives to combine therapeutic vaccines and antivirals (NUCs). We also disclose potential applications of this product in novel fields of immunotherapy.
RESUMEN
We discuss the suitability of innate immune stimulation in acute respiratory infection post-exposure prophylaxis. The induction of innate immunity can be used to reduce susceptibility to immune-evasive pathogens (coronavirus, influenza virus, respiratory syncytial virus and rhinovirus). After the emergence of multiple SARS-CoV-2 variants, scientists are debating whether new variants could affect vaccine efficacy and how antigens could be redesigned to compensate. In addition, there is insufficient vaccine production to cover universal demand, and equitable vaccine distribution is a global challenge. Given these factors, non-specific immune stimulators may be suitable for a quick first response in the case of a suspected or early respiratory infection. Our group completed several HeberNasvac studies in healthy volunteers and patients with respiratory infections, and is currently starting large clinical trials in patients with early SARS-CoV-2 infections. This nasal formulation of hepatitis B vaccine has demonstrated its capacity to stimulate innate immunity markers (TLR3, TLR7 and TLR8 in tonsils) at the virus' entry site, in systemic compartments (HLA class II in monocytes and lymphocytes) and in the activation of dendritic cells, lymphocytes and other cell lines in vitro and ex vivo. In addition, research generated by the current pandemic may obtain results useful for treating other acute respiratory infections, which have long been main drivers of mortality among older adults and in early childhood.