VBI pits hepatitis B candidate against GlaxoSmithKline's Engerix-B in head-to-head phase 3

If approved in the U.S., VBI Vaccines' hepatitis B vaccine would compete against Dynavax's new shot, Heplisav-B, as well as GlaxoSmithKline's Engerix-B.

After getting go-aheads from multiple regulatory agencies, VBI Vaccines started phase 3 testing of its hepatitis B vaccine Sci-B-Vac against its future rival, GSK's Engerix-B, aiming to file for approvals in 2019.

The phase 3 program is divided into two parallel studies. The first one, which will enroll 1,600 adult participants, will test Sci-B-Vac head to head against GlaxoSmithKline’s approved hepatitis B shot Engerix-B, hoping to demonstrate that Sci-B-Vac is equally protective—or even superior—in adults older than 45. The second test will divide about 3,200 adults into four groups to analyze the vaccine’s consistency.

Given that the vaccine is already approved in 15 countries and has been administered to more than 500,000 people in a commercial setting, VBI says it's confident about the program. Based on data from studies elsewhere, company CMO Francisco Diaz-Mitoma, M.D., Ph.D., previously predicted that Sci-B-Vac’s superiority margin over Engerix-B in those older than 45 could exceed 5%.

RELATED: With eyes on Glaxo's Engerix-B vaccine, VBI takes hep B candidate into phase 3

The company attributes the vaccine’s potential advantage to its composition. Apart from the S antigen already used in Engerix-B, Sci-B-Vac also contains the pre-S1 and pre-S2 surface antigens, which add to its efficacy, according to the biotech.

Sci-B-Vac is offered as a three-dose regimen, but VBI has data suggesting two doses might be enough. CEO Jeff Baxter has said VBI might pursue approval for the two-dose regimen. It's currently produced at VBI’s mammalian cell-derived vaccine manufacturing facility in Israel, but the facility needs to pass an FDA inspection before the product can be marketed in the U.S.

RELATED: Persistence pays off for Dynavax as twice-rejected hepatitis B vaccine wins FDA nod

Even as VBI Vaccines pursues additional approvals for its shot, the hepatitis B vaccine market recently had a shake-up with Dynavax's FDA approval for Heplisav-B, which analysts believe could generate $300 million in peak sales. Dynavax plans to launch the shot on its own, CEO Eddie Gray told FiercePharma, rather than seek a larger partner.

Cambridge, Massachusetts-based VBI Vaccines recently completed a $71.9 million round of equity financing via an underwritten public offering and registered direct offering. It plans to use the proceeds to fund the pivotal Sci-B-Vac trials, as well as a phase 1/2a study of a therapeutic vaccine for glioblastoma multiforme and further development of a prophylactic vaccine to prevent cytomegalovirus that’s currently in phase 1.

Without hepatitis B approvals in major markets, VBI’s revenues for the first nine months of 2017 were just $664,000.