Overcoming Immunotolerance in Chronic Hepatitis B: Efficacy of Granulocyte-Macrophage Colony-Stimulating Factor-Based Immunotherapy in Achieving Hepatitis B Surface Antigen Seroclearance.

Chronic hepatitis B (CHB) remains incurable due to the immune system's tolerance toward the hepatitis B virus (HBV) surface antigen (HBsAg). This study aimed to achieve a functional cure by breaking HBV tolerance through immunotherapy. CHB patients were treated with either standard nucleotide analog (NA) therapy (Adefovir Dipivoxil, ADV) (Cohort 1) or ADV combined with interferon-alpha (IFN-α) (Cohort 2). Additionally, a third cohort received the THRIL-GM-Vac regimen: three low-dose GM-CSF injections followed by one dose of the HBV vaccine, alongside standard treatment. THRIL-GM-Vac treatment (Cohort 3) achieved a significant 2log10 reduction in HBsAg levels in 21.7% of participants, and 8.7% HBsAg clearance in Cohort 3 compared to 0% and 4.17% in Cohorts 1 and 2, respectively. Furthermore, THRIL-GM-Vac significantly reduced HBV-specific tolerogenic T cells (Tregs), explaining the sustained HBsAg decrease. Upregulation of anti-HBV T cell responses confirmed THRIL-GM-Vac's ability to disrupt HBV tolerance and enhance HBsAg-specific cellular immunity. This suggests its potential effectiveness in treating individuals with moderate to low HBsAg levels. THRIL-GM-Vac treatment in Cohort 3 resulted in 8.7% HBsAg clearance alongside Treg depletion and enhanced anti-viral T cell responses. These findings present a promising strategy to overcome immunotolerance and potentially combat chronic HBV infection.