Three-antigen HBV vaccine produces high seroprotection rates in adults
A three-antigen hepatitis B virus vaccine candidate produced significantly higher seroprotection rates in adults compared with a monovalent vaccine, according to results from the phase 3 PROTECT study.
The findings were presented as part of the virtual Annual Conference on Vaccinology Research sponsored by the National Foundation for Infectious Diseases.
“Adult hepatitis B virus infection remains a global public health concern, and prophylactic vaccination is a critical prevention measure. Improved HBV vaccines are needed to ensure safe and effective seroprotection against HBV for those who are older, obese, or those with impaired immune function, including diabetics,” Francisco Diaz-Mitoma, MD, PhD, chief medical officer at VBI Vaccines, told Healio. “Currently licensed HBV vaccines have reduced immunogenicity in these key immunocompromised at-risk adult populations.”
According to Diaz-Mitoma, VBI’s three-antigen HBV vaccine candidate is scientifically differentiated from other licensed single-antigen vaccines, prompting the company to design a global phase 3 clinical program consisting of the PROTECT and CONSTANT studies to support potential regulatory submission applications in the United States, Europe and Canada.
PROTECT was a double-blind, randomized, controlled phase 3 trial comparing the immunogenicity and safety of the three-antigen vaccine (3A-HBV) with the single-antigen vaccine Engerix-B (1A-HBV, GlaxoSmithKline) among adults aged 18 years or older, including those with stable chronic conditions.
In the study, participants were randomly assigned to receive three intramuscular injections at months 0, 1 and 6. The primary objectives were noninferiority of seroprotection rates (SPR) and superiority of SPR in adults aged 45 years or older for 3A-HBV compared with 1A-HBV at 4 weeks after the third dose.
According to the study, at day 196, the SPR for participants aged 18 years or older was significantly higher for 3A-HBV compared with 1A-HBV (91.4% vs 76.5%), and the SPR for participants aged 45 years or older was also superior for 3A-HBV compared with 1A-HBV (89.4% vs 73.1%).
The study also demonstrated that the SPR for participants with diabetes was significantly higher with 3A-HBV than 1A-HBV (83.3% vs 58.3%), and it was higher for participants with a BMI greater than 30 kg/m2 (89.2% vs 68.1%). The mean geometric mean concentration of serum anti-hepatitis B surface antibodies was higher for 3A-HBV compared with 1A-HBV (1,424.5 vs 235.4 mIU/mL) at day 196 and consistently higher across all key subgroups.
“The PROTECT study showed that VBI’s vaccine was able to safely elicit more rapid and robust immune responses in adults compared to Engerix-B and was more immunogenic in immunocompromised subgroup populations who historically have been harder to protect with single-antigen HBV vaccines,” Diaz-Mitoma said. “We believe VBI’s three-antigen HBV vaccine can be a meaningful intervention in the fight to eliminate hepatitis B infection with the potential to decrease morbidity and save lives.”
Diaz-Mitoma said the results from PROTECT, as well as those from the concurrently running CONSTANT study, will be the basis for regulatory submissions in North America and Europe. Currently, the vaccine is approved for use and commercially available in Israel under the name Sci-B-Vac. A biologics license application has been accepted for review by the FDA — the PDUFA target date is Nov. 30 — and a marketing authorization application has been accepted for review by the European Medicines Agency.
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Diaz-Mitoma F, et al. Higher seroprotection rates (SPR) and anti-HBs titers achieved in adults with a 3-antigen hepatitis B vaccine (3A-HBV) compared to a 1-antigen hepatitis B vaccine (1A-HBV): Results of the PROTECT study. Presented at: NFID Annual Conference on Vaccinology Research; April 26-28, 2021 (virtual meeting).
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