Vaccitech, a clinical-stage biopharma company developing immunotherapies to treat and prevent infectious diseases and cancer, has announced that it has dosed the first person in Phase 1 clinical study to investigate the safety and immunogenicity of the VTP-300 prime in both healthy participants and patients with chronic hepatitis B (HBV) who are virally suppressed with oral antiviral medication.

The VTP-300 prime comprises Vaccitech’s Chimpanzee Adenovirus Oxford 1 (ChAdOx1), a non-replicating viral vector delivering three full-length HBV antigens to stimulate a vigorous antibody and mixed CD4+/CD8+ T cell immune response. The study, HBV001, will evaluate the ability of VTP-300 prime to generate anti-HBV CD4+ and CD8+ T cells; immune cells known to be involved in the clearance of HBV from the liver.

HBV001, is an open-label, non-randomised, dose-escalation study, comparing the safety, tolerability and immunogenicity of two different doses of the VTP-300 prime, ChAdOx1-HBV, across three sites in the UK. It is planned to enrol 10 healthy participants and 12 patients with chronic HBV infection.

Once the VTP-300 prime dose is confirmed, Vaccitech plans to initiate a Phase 1b/2a study, HBV002, in Q3 2020 using the complete VTP-300 heterologous prime-boost regimen. The regimen consists of ChAdOx1-HBV (the prime) and a second non-replicating viral vector, a Modified Vaccinia Ankara (MVA), delivering the same HBV antigens (the boost).

HBV002 will be an international, randomised, open-label study, to be run in Taiwan, China, South Korea and the UK. It is designed to enrol 64 chronically infected HBV patients and assess efficacy through a reduction in serum HBV surface antigen. VTP-300 will be administered in combination with standard of care antivirals that limit viral replication and low doses of an anti-PD-1 agent to counteract the T cell exhaustion typically present in chronic HBV patients. Initial data from HBV002 is anticipated in Q3 2021.