Barinthus Bio's VTP-300 Trials Show Success in Reducing HBsAg in Chronic Hepatitis B

Barinthus Biotherapeutics plc (NASDAQ: BRNS), a biopharmaceutical company specializing in T cell immunotherapeutics, recently presented updated data from two ongoing clinical trials focused on chronic hepatitis B (CHB) at the European Association for the Study of the Liver (EASL) Congress 2024. These updates involve a Phase 2b trial (HBV003) and a Phase 2a trial (IM-PROVE II, AB-729-202) in collaboration with Arbutus Biopharma (NASDAQ: ABUS).

Interim HBV003 Data: VTP-300 and Low-dose Nivolumab

The HBV003 trial revealed that VTP-300 combined with low-dose nivolumab was well-tolerated, showing significant and sustained reductions in hepatitis B surface antigen (HBsAg) levels, with some participants achieving undetectable HBsAg. As of April 15, 2024, 91 out of 120 planned participants were enrolled, with 40 having HBsAg ≤200 IU/mL at screening. Data from 21 participants assessed for NUC (nucleos(t)ide analogue) discontinuation showed promising outcomes:
- 76% (16 out of 21) were eligible for NUC therapy discontinuation at the end of treatment (EOT), with seven of these actually discontinuing.
- Of those who discontinued, 71% (5 out of 7) remained off NUC therapy for up to 44 weeks.
- 19% (4 out of 21) had undetectable HBsAg levels.
- 67% (14 out of 21) had HBsAg levels below 10 IU/mL at Week 24 or later.
- Robust T cell responses were observed, and no serious adverse events related to the treatment were reported. The most common adverse event was thyroid dysfunction, affecting 9% of participants.

Bill Enright, CEO of Barinthus Bio, highlighted that these results support VTP-300 as a potential critical component of a functional cure regimen for CHB, reshaping the treatment landscape.

Prof. Man-Fung Yuen from Queen Mary Hospital, University of Hong Kong, expressed optimism about VTP-300's potential to suppress the virus and provide a functional cure, potentially allowing patients to halt lifelong therapies and prevent liver failure or cancer progression.

End of Treatment IM-PROVE Interim Data: Imdusiran and VTP-300

As of April 12, 2024, interim data from the IM-PROVE II trial showed that imdusiran (Arbutus’ RNAi therapeutic candidate) followed by VTP-300 maintained low HBsAg levels during the follow-up period. Dr. Kosh Agarwal from King’s College Hospital, London, presented findings from 38 participants on stable NUC therapy:
- Imdusiran led to significant reductions in HBsAg levels, with 95% achieving levels below 100 IU/mL before entering the VTP-300 or placebo groups.
- At 24 weeks post-EOT, VTP-300 showed a statistically significant reduction in HBsAg compared to placebo.
- At EOT (Week 48), 94% in the VTP-300 group had HBsAg <100 IU/mL, with 36% achieving <10 IU/mL, compared to 84% and 21% in the placebo group, respectively.
- At 24 weeks post-EOT, 80% in the VTP-300 group maintained HBsAg <100 IU/mL, with 60% achieving <10 IU/mL, compared to 16% and 0% in the placebo group.
- 84% of participants in the VTP-300 group met criteria to discontinue NUC therapy versus 52% in the placebo group.

Dr. Agarwal noted the significant reduction in HBsAg levels and the number of patients qualifying to stop NUC therapy in the VTP-300 group. Dr. Nadege Pelletier, Chief Scientific Officer of Barinthus Bio, emphasized the role of VTP-300 in maintaining low HBsAg levels and its potential when combined with imdusiran, with further data expected later in the year.

About VTP-300

VTP-300 is an immunotherapeutic utilizing a ChAdOx vector followed by MVA vector doses, encoding multiple HBsAg components. It's the first antigen-specific immunotherapy showing sustained HBsAg reductions, studied in combination with agents like siRNA and low-dose anti-PD-1 antibodies.

About HBV

Chronic hepatitis B affects approximately 254 million people worldwide, leading to significant morbidity and mortality. Despite the high prevalence, diagnosis and treatment rates remain low.

About Barinthus Biotherapeutics

Barinthus Bio is a clinical-stage biopharmaceutical company advancing a pipeline of T cell immunotherapeutic candidates aimed at treating chronic infectious diseases, autoimmune disorders, and cancer. Their portfolio includes VTP-300 for chronic HBV, among other candidates targeting various high-impact diseases.

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