A groundbreaking preclinical study demonstrates that combining a ferritin nanoparticle-preS1 therapeutic vaccine with small interfering RNA (siRNA) achieved 100% sustained seroconversion in chronic hepatitis B (CHB) mouse models, representing a significant advancement toward a functional cure for this global health challenge affecting over 254 million people worldwide.
The research, published in hLife, shows that the combination treatment resulted in complete and sustained serum hepatitis B surface antigen (HBsAg) loss across an approximate 11-month period, with about an 80% seroconversion rate for HBs antibodies, stable persistence of anti-HBs, and 70% clearance rates of serum HBV DNA and liver hepatitis B core antigen (HBcAg).
Novel Vaccine Approach Targets Low-Tolerant Antigen
The ferritin-NP-preS1 vaccine represents an innovative approach to overcoming HBV-specific immune tolerance. Traditional therapeutic vaccines face challenges due to immune tolerance induced by high levels of HBsAg. By targeting the low-tolerant preS1 antigen and using ferritin nanoparticles to improve immunogenicity, researchers were able to elicit strong and sustained anti-preS1 responses and preS1-specific CD4+ T-cell responses.
In previous studies, the ferritin-NP-preS1 vaccine alone achieved effective viral clearance and approximately 50% serological conversion in CHB mouse models. However, the addition of siRNA treatment appears to significantly enhance these outcomes by inducing viral antigen loss and reversing HBV-specific immune tolerance.
Among the 10 mice that received the combination regimen, liver covalently closed circular DNA and HBcAg were significantly diminished to undetectable levels, demonstrating the treatment's ability to target multiple aspects of viral persistence.
RNA Interference Emerges as Game-Changing Strategy
The success of this combination approach aligns with broader developments in RNA interference therapeutics for hepatitis B treatment. According to research published in Science Translational Medicine, RNAi therapeutics represent a major advancement in chronic HBV treatment by addressing viral antigens, silencing the virus, and helping reinvigorate the body's immune response.
"We're really excited about some of these RNAi's because they seem to have two modes of action, both suppressing the viral antigens and turning on the immune system," said John Tavis, Ph.D., professor of molecular microbiology and immunology at Saint Louis University School of Medicine. "There is a particular drug we reviewed, Bepirovirsen by GlaxoSmithKline, that not only suppresses HBV for many months, even after the drug is stopped, but it also has a second mechanism that is triggering the immune system to go in and help with the job."
Three-Pronged Treatment Strategy Shows Clinical Promise
Researchers believe a functional cure for chronic hepatitis B could be achieved through combination therapies employing three complementary mechanisms: blocking viral replication, suppressing viral antigens, and stimulating immune system response.
"We want to turn down the smokescreen that the virus is putting up, all of those extra virus proteins that are in the bloodstream, by getting rid of the antigens. Then we want to turn on the immune system, all the while blocking viral replication," Tavis explained. "If we do those three things together, we're eventually going to clear the virus."
Current clinical trials using combination therapies that often include RNAi drugs are achieving functional cure rates of approximately 30% after one to one-and-a-half years of treatment, representing substantial improvement over the 5% success rate of standard care approaches.
Addressing Critical Global Health Need
Chronic hepatitis B remains a significant global health challenge, with more than 1.1 million hepatitis B-related deaths occurring annually. The virus affects approximately 4% to 8% of the adult population in resource-limited regions such as sub-Saharan Africa and the Asia-Pacific region.
Between 20 and 40 percent of those with chronic HBV infection are expected to die from the disease if left untreated, usually from liver failure or liver cancer. The progressive disease causes half of all liver cancer cases and significantly impacts quality of life through liver fibrosis and cirrhosis.
A functional cure, defined as eliminating viral DNA and surface antigen for at least six months post-therapy, would dramatically reduce a person's risk of future health complications to levels comparable to those who experienced acute infection and natural clearance.
The researchers emphasize that further clinical validation is needed to translate these promising preclinical findings into therapeutic options for patients with chronic hepatitis B.
