In February 2023 VBI Vaccines announced interim data from a Phase II study evaluating a combination treatment of VBI-2601 (BRII-179) and BRII-835 (VIR-2218) in chronically infected HBV patients. The data demonstrates that the therapy was “generally well-tolerated”. It also “restored strong anti-HBsAg antibody responses and led to improved HBsAg-specific T-cell responses, when compared to BRII-835 alone”.  


VBI-2601 is a “novel recombinant, protein-based HBV immunotherapeutic candidate”. VBI states that it “builds upon the 3-antigen conformation of VBI’s prophylactic 3-antigen HBV vaccine candidate” and is intended to treat enhanced B-cell and T-cell immunity.  

The trial 

The Phase II study is a randomised, multi-centre trial across sites in Australia, Taiwan, Hong Kong, South Korea, New Zealand, Singapore, and Thailand. It is sponsored by VBI’s partner Brii Biosciences. 

Interim data were generated from 50 adult, non-cirrhotic patients who received “nucleos(t)ide reverse transcriptase inhibitor (NRTI) therapy” for at least 12 months. They were randomised and dosed across three cohorts: 

  • BRII-835 Alone Regimen – Nine subcutaneous 100mg doses of BRII-835, dosed every four (4) weeks through Week 32 
  • BRII-835 Alone Regimen + nine 40µg intramuscular doses of VBI-2601 admixed with interferon-alpha (IFN-α) as co-adjuvant every four weeks from Week 8 through Week 40 
  • BRII-835 Alone Regimen + nine 40µg intramuscular doses of VBI-2601 without IFN-α every four weeks from Week 8 through Week 40 
Novel combinations 

Dr Francisco Diaz-Mitoma, VBI’s Chief Medical Officer, stated that “numerous studies” have already assessed the potential of siRNA candidates in HBV patients, but this is the “first time we’ve seen data from the combination of an HBV siRNA with an HBV-specific immunomodulator”.  

“We are very encouraged by these interim data, which suggest that the combination…has the potential to be a meaningful part of a functional cure regimen.” 

Further data are expected “later this year”. For more on the challenges associated with the development of HBV therapies, read our interview with Dr Andrew Vaillant here.  

We will hear more about HBV approaches at the World Vaccine Congress in Washington this April. Join us there by getting your tickets now!