The cohort level unblinded data from the study demonstrated that in the intent to treat analysis at Week 24 (end of treatment or EoT), 26.3% (15 patients) treated with BRII-179/PEG-IFNα achieved HBsAg loss compared to 19.3% (11 patients) with placebo/PEG-IFNα; at Week 36 (12 weeks follow-up), 24.6% (14 patients) treated with BRII-179/PEG-IFNα had HBsAg loss, compared with 14.0% (8 patients) with placebo/PEG-IFNα. In the per protocol analysis at Week 24, 32.6% (15 patients) treated with BRII-179/PEG-IFNα achieved HBsAg loss compared to 21.6% (11 patients) with placebo/PEG-IFNα; at Week 36, 31.8% (14 patients) and 14.9% (7 patients) had HBsAg loss, respectively. In addition, 9 out of 15 patients in the cohort treated with BRII-179/PEG-IFNα achieved HBsAg seroconversion at EoT (Week 24), versus 1 out of 11 in the cohort treated with PEG-IFNα alone. The cohort level unblinded 24 weeks safety data showed BRII-179/PEG-IFNα treatment was generally safe and tolerated, with adverse events similar to those associated with PEG-IFNα treatment or BRII-179 as previously reported. Follow up is ongoing.

"We are excited by the data from this proof-of-concept study consistent with our previous proof-of-mechanism studies that BRII-179 induces functional immune responses complementing other curative treatment modalities such as PEG-IFNα," said David Margolis, MD, Chief Medical Officer of Brii Bio. "We look forward to continuing the evaluation of this first-in-class immunotherapeutic candidate through our ongoing and future studies as we work to deliver the highest HBV functional cure rates to the 290 million people around the world living with HBV."

Promising results from multiple studies, including Vir Biotechnology's study evaluating BRII-835 (VIR-2218) with or without PEG-IFNα, and Brii Bio's ongoing Phase 2 trial combining BRII-179 with BRII-835, have shown a strong correlation between durable HBsAg seroclearance and antibody responses, highlighting the potential of BRII-179 as a valuable immunomodulatory component within an HBV functional cure regimen.

Meanwhile, Brii Bio's newly launched Phase 2 HBV study evaluating BRII-835 + PEG-IFNα versus PEG-IFNα active control arm, aims to clarify the additional functional cure efficacy of the combination. The Company intends to include patients in the APAC region who were previously exposed to BRII-179 in the Phase 2 study. The Company believes that BRII-179 has the unique ability to distinguish patients who have significant intrinsic humoral immunity versus those who do not.

In July 2023, Brii Bio expanded the BRII-179 (VBI-2601) license from VBI Vaccines (Nasdaq: VBIV) to global rights. The Company is planning for additional combination studies in the near future to investigate BRII-179 as a primer to enhance antibody responses and enrich patients for potentially curative treatments.