Vaccitech plc announced an update to the interim analysis of safety and efficacy data from its HBV002 trial (NCT04778904). The data will be presented as a poster at the 2022 American Association for the Study of Liver Disease (AASLD) - The Liver Meeting® by Dr. Young-Suk Lim, Professor of the Department of Gastroenterology and the Liver Center, Asian Medical Center, University of Ulsan College of Medicine, Korea. Vaccitech's updated interim analysis includes data from the fully-enrolled trial of 55 patients with chronic hepatitis B (HBV) with at least three months of follow-up.

It shows that VTP-300 induced meaningful, sustained reductions of HBV surface antigen (HBsAg) in people with chronic HBV. Declines were most prominent in patients with lower baseline HBsAg. HBsAg is a hallmark of chronic HBV infection.

Fewer than 10% of patients on current standard-of-care HBV therapies achieve sustained HBsAg decrease or loss, a state associated with functional cure of the disease. VTP-300 administered as a monotherapy or in combination with a single administration of low-dose nivolumab at the time of the booster dose was administered with no treatment-related serious adverse events and infrequent transient transaminitis as of 28 September 2022. In the VTP-300 monotherapy Group 2 (N=18), five patients had baseline HBsAg under 100 IU/mL.

Of those five patients, three showed meaningful and durable reductions of HBsAg of 0.9, 1.0 and 1.4 log10, respectively, five months after the last dose of VTP-300. Furthermore, these reductions persisted in all three patients at eight months after the last dose. Group 3 (N=18) patients received VTP-300 in combination with a single low dose of nivolumab at the time of the booster dose, and the mean log10 reduction in HBsAg was 0.8 (n=18) at 3 months, 0.9 (n=10) at 6 months, and 1.3 (n=7) at 9 months, with more prominent declines observed in patients with baseline HBsAg lower than 1,000 IU/mL.

Five patients in this group had baseline HBsAg lower than 100 IU/mL, of which four had declines over 0.6 log10. Moreover, two of those patients developed non-detectable HBsAg at 3 months, and one of the patients, who has been evaluated at 6 and 9 months, continued to maintain non-detectable HBsAg. Patients in Groups 2 and 3 also demonstrated a robust CD8+ T cell response, against all encoded antigens; core protein, polymerase and surface antigens.

No meaningful reductions in HBsAg were observed in Group 1 in which patients received two doses of Modified Vaccinia Ankara (MVA)-HBV without ChAdOx1-HBV, or in Group 4 in which patients received low-dose nivolumab with both doses of VTP-300. These groups were discontinued after interim analysis, as previously announced in June 2022. Enrollment in the HBV002 trial is complete, with a final update expected early in the second quarter of 2023.

A trial to evaluate timing of low dose nivolumab and additional doses of the MVA boost component of VTP-300 (HBV003; NCT05343481) has been initiated in multiple countries within the Asia-Pacific region.