VBI Vaccines takes a shot at HBV Phase 3
- VBI Vaccines' is poised to begin two Phase 3 trials that will test Sci-B-Vac, a third-generation hepatitis B vaccine, in the U.S., Europe and Canada and enroll around 4,800 people.
- One trial, named PROTECT, will evaluate the drug's safety and immunogenicity, with 1,600 adults receiving three doses of Sci-B-Vac or GlaxoSmithKline's Engerix-B. The primary objectives are non-inferiority of the seroprotection rate in adults, and superiority of the seroprotection rate in people over 45 years. The other study, CONSTANT, will assess the lot-to-lot consistency of Sci-B-Vac in 3,200 adults aged 45 years or younger.
- Both studies, which are slated to run across 15 months, will begin enrollment in the second half of 2017. VBI Vaccines already has data from about 2,000 people from earlier clinical trials, and its vaccine is already approved for use in 15 other countries.
Hep B kills around 780,000 people each year worldwide through liver cirrhosis, liver cancer and other outcomes. Vaccines treating the illness were first developed in the late 1970s and have been used for decades.
However, levels of seroprotection — or how well the body can ward off infection, usually after a vaccination — can fall in people who are older, obese, smokers and HIV-positive.
Second-generation hep B vaccines, created using transfected yeasts, generally treated the disease by targeting what's called the "S" surface antigen. VBI Vaccine's approach, meanwhile, is to target that antigen as well as the pre-S1 and pre-S2 surface antigens, which the company believes will be more effective in people who have lower responses to vaccination.
Hep C has been transformed by the near-curative drugs. However, hep B 'cures' are further off, with nothing on the market so far approaching this, according to Timothy M. Block, president of the Hepatitis B Foundation. Approaches to the treatment of hep B include direct-acting antivirals, which target the virus lifecycle, and indirect-acting antivirals, which use the body's own immune responses to tackle the disease.
Potential approaches to direct acting antivirals include siRNA (silencing RNA), tenofovir produgs, entry inhibitors, and CRISPR/cas and TALEN genome editing systems. Indirect acting antiviral approaches include toll-like receptor agonists and cyclophilin inhibitors.
Looking at a handful of examples: Alnylam's RNAi therapeutic, ALN-HBV, is in early-stage clinical development for the treatment of chronic HBV infection. German company MYR has conducted Phase 2 trials with Myrcludex B, an entry inhibitor with potential in both hep B and hep D. Novira Therapeutics also has a number of approaches –such as its lead core inhibitor, NVR 3-778, which is in Phase 1a, and a second-generation core inhibitor in discovery.
- VBI Vaccines Statement
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