Hepatitis B Vaccine to Begin Phase 3 Clinical Trials

VBI Vaccines recently announced plans to begin phase 3 clinical testing for Sci-B-Vac, a third-generation hepatitis B virus (HBV) candidate vaccine. The assessment follows positive discussions with the FDA, European Medicines Agency (EMA), and Health Canada, according to a press release.

Second-generation vaccines contain 1 surface antigen, while the Sci-B-Vac contains the surface antigen and pre-S1 and pre-S2 surface antigens, according to the release. VBI reports that third-generation vaccines may prove more effective among patients who do not respond to second-generation vaccines.

The phase 3 program will include 2 clinical trials spanning 15 months. The PROTECT study will explore the safety and immunogenicity of Sci-B-Vac, while the CONSTANT study will explore the lot-to-lot consistency of the vaccine, according to the release. VBI expects to enroll approximately 4800 patients across 40 sites in the United States, Europe, and Canada.

The PROTECT study will enroll approximately 1600 adults who will be randomized 1:1 to receive 3 doses of Sci-B-Vac 10μg or 3 doses of Engerix-B 20μg, a control vaccine, according to the release.

The primary objectives of the trial include: non-inferiority of seroprotection rate of the vaccines at 4 weeks after third vaccination in adults; superiority of seroprotection from Sci-B-Vac at 4 weeks after third vaccination in adults 45 years and older, according to VBI.

The study will also analyze the speed of seroprotection and safety and tolerability of the candidate vaccine.

The CONSTANT study will enroll 3200 adults aged 18 to 45 years. Patients will be randomized 1:1:1:1 to receive 3-dose courses of Sci-B-Vac from different lots or the control vaccine, according to the release.

The primary objective of the study is to demonstrate lot-to-lot consistency for immune response across lots of the vaccine. The study will also examine the safety and efficacy of Sci-B-Vac.

Sci-B-Vac is a licensed third-generation HBV vaccine currently approved in Israel and 14 countries. It has demonstrated safety and efficacy in more than 300,000 patients thus far, according to VBI.

“We consider the outcome of discussions with the FDA, EMA, and Health Canada to be extremely positive,” said Jeff Baxter, president and CEO of VBI Vaccines. “Sci-B-Vac’s extensive safety and efficacy data package demonstrates safe and effective vaccination of approximately 2000 subjects in past clinical trials. Because of this track record, we are able to plan a Phase 3 program that will enroll only 4800 subjects in total and will be only 15-months in duration. We anticipate initiating enrollment in both Phase 3 studies in the second half of 2017.”