Safety of a two-dose investigational hepatitis B vaccine, HBsAg-1018, using a toll-like receptor 9 agonist adjuvant in adults.

Background: Hepatitis B virus infection remains an important global public health problem. Approved alum-adjuvanted vaccines are well tolerated but require three doses and have reduced immunogenicity in adults. A two-dose vaccine containing hepatitis B surface antigen combined with a novel, Toll-like receptor 9 agonist adjuvant (HBsAg-1018 [HEPLISAV-B®]) has demonstrated significantly higher seroprotection rates than a three dose vaccine.

Methods: A post hoc analysis compared the safety of HBsAg-1018 with HBsAg-Eng (Engerix-B®), in three randomized, observer-blinded, active-controlled, multi-center phase 3 trials in adults. HBsAg-1018 was administered intramuscularly at weeks 0 and 4 and placebo at week 24 and HBsAg-Eng at weeks 0, 4, and 24.

Results: Post-injection reactions, adverse events, medically attended adverse events, and new-onset immune-mediated adverse events were balanced between vaccine groups. Anti-nuclear antibodies, anti-double stranded DNA antibodies, anti-neutrophil cytoplasmic antibodies, and antiphospholipid antibodies were balanced between groups. A transient increase in anti-beta2 glycoprotein 1 IgM was observed in the HBsAg-1018 group but was not associated with a thrombotic event. Serious adverse events and deaths were generally balanced between groups.

Conclusion: HBsAg-1018 had a similar safety profile to HBsAg-Eng. With improved immunogenicity and fewer doses over a shorter time, HBsAg-1018 has the potential to provide improved seroprotection and a significant public health benefit to adults 18 years of age or older.