Vaccitech Announces Positive Topline Final Data for HBV002 Study in People with Chronic Hepatitis B

pharmafile | March 28, 2023 | News story | Business Services  

OXFORD, United Kingdom, March 28, 2023 (GLOBE NEWSWIRE) — Vaccitech plc (NASDAQ: VACC), a clinical-stage biopharmaceutical company focused on the development of novel T cell immunotherapeutics designed to use the power of the immune system to potentially treat and cure chronic infectious diseases, autoimmune diseases and cancer, today announced positive topline final data from the HBV002 study (NCT04778904), a Phase 1b/2a clinical trial of VTP-300 in people with chronic Hepatitis B (HBV) infection.


The completed trial, which included 55 patients with chronic hepatitis B, supported the generally favorable tolerability profile previously reported with VTP-300, with no incidents of VTP-300-related Grade 3 adverse events or product-related serious adverse events following study dosing. VTP-300 was observed to induce meaningful, sustained reductions of Hepatitis B surface antigen (HBsAg) in patients with chronic HBV. Declines were most prominent in patients with lower baseline HBsAg. The final results of the immunology assays are currently being analyzed and the full data, including tolerability and immunogenicity results, will be presented at the upcoming EASL Congress, June 21-24, 2023. 


“The safety data and HBsAg reductions in the HBV002 study are very encouraging and we look forward to sharing the full data set, including immune responses, at the EASL conference,” said Bill Enright, CEO of Vaccitech. “Less than 10% of people with chronic HBV reach a functional cure with current therapies. We believe VTP-300 has the potential to be a critical component of functional cure for HBV, potentially eliminating the need for chronic treatment. Our ongoing trials are exploring dosing, including an additional booster, and combination approaches with readouts expected towards the end of the year.”


Topline Study Results

HBV002 was an open-label study to evaluate the safety, tolerability and immunogenicity of VTP-300, with or without low-dose nivolumab, in people with chronic HBV who are virally suppressed with oral anti-viral therapies. In the HBV002 study, 55 participants were randomized into four groups to receive combinations of VTP-300 and low-dose nivolumab, with follow-up for nine months after the first dose. 


In the VTP-300 monotherapy group (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 0.9-1.4 log10 at five and eight months after the last dose of VTP-300. 


Group 3 (N=18) patients received VTP-300 in combination with a single low dose of nivolumab at the time of the booster dose. The mean log10 reduction in HBsAg was 0.8 at 3, 6, and 9 months (n=18, 18, and 17, respectively), with more prominent declines observed in patients with baseline HBsAg lower than 1,000 IU/mL (mean log10 reduction of 1.0 at 3, 6, and 9 months [n=13 at each timepoint]). Five patients in this group had baseline HBsAg lower than 100 IU/mL, of which three had persistent declines ranging from 1.4 to 3.4 log10 at 9 months. Moreover, two of these patients developed non-detectable HBsAg at 3 months, which persisted in both patients at eight months after the last dose, as assessed in a post-hoc analysis.   


T cell immune responses to the HBV antigens encoded in VTP-300, as measured by ELISpot assay, were observed in the majority of individuals in Groups 2 and 3. In some responders, decreases in viral replication (measured via pre-genomic RNA) were noted and consistent with declines in HBsAg (viral load). Immune responses were seen across both virus genotypes B and C, which is consistent with studies of cross reactivity to the HBV core protein in healthy controls, where almost complete immunologic cross reactivity was seen to Hepatitis B virus genotypes A-E.


While there were no incidents of Grade 3 adverse events or serious adverse events related to VTP-300, transaminase flares occurred in two patients. Both of these incidents occurred in patients with HBsAg declines, but not in any of the patients who cleared HBsAg (<0.05 IU/mL).


A Phase 2b clinical 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, with interim data expected in Q4 2023. In addition, a Phase 2a clinical trial, in collaboration with Arbutus Biopharma Corporation (NASDAQ: ABUS), is evaluating the safety, antiviral activity and immunogenicity of VTP-300 administered after Arbutus’ AB-729 in 40 virologically-suppressed chronic HBV patients, with interim data expected in Q4 2023.


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