Brii Biosciences Announces Topline Interim Results of Phase 2 Study Evaluating BRII-179 (VBI-2601) in Combination with PEG-IFNα for the Treatment of Chronic Hepatitis B

BRII-179 (VBI-2601) as an add-on therapy to standard of care PEG-IFNα increases HBsAg loss rate at the end of treatment and 12 weeks follow up

Significantly increased HBsAg seroconversion rate is strongly associated with BRII-179 treatment and correlates with the increased rate of HBsAg loss

Safety findings are similar to those of PEG-IFNα therapy and BRII-179 as previously reported

DURHAM, N.C. and BEIJING, Sept. 6, 2023 /PRNewswire/ -- Brii Biosciences Limited ("Brii Bio," "we," or the "Company," stock code: 2137.HK), a biotechnology company developing therapies to improve patient health and choice across diseases with high unmet need, today announced topline cohort-level unblinded Week 24 and Week 36 data from interim analysis of a randomized, placebo-controlled and double-blinded Phase 2 study of BRII-179, a first-in-class Pre-S1/Pre-S2/S therapeutic vaccine, in combination treatment with pegylated interferon-alpha (PEG-IFNα) in patients with chronic hepatitis B (CHB) compared with PEG-IFNα only treatment. We reported in previous studies that BRII-179 induced broad antibody and T-cell responses against Pre-S1, Pre-S2 and S epitopes in CHB patients.

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.

More detailed data will be shared at a future scientific conference.

About BRII-179 (VBI-2601) + PEG-IFNα Combination Study

The Phase 2 study is a multicenter, randomized, double-blind, placebo-controlled, parallel study designed to evaluate the safety and efficacy of BRII-179 as an add-on therapy to PEG-IFNα and NrtI therapy for the treatment of chronic HBV infection. This study enrolled adult HBV patients in mainland China who had received 24 to 28 doses of PEG-IFNα per treatment guideline, at least 12 months of NrtI therapy, and met a pre-defined criteria for partial response. Subjects were randomized 1:1 to receive BRII-179 or placebo every three weeks for a total of 7 doses over 18 weeks while continuing PEG-IFNα treatment for 24 weeks. Subjects who met Nrtl discontinuation criteria will stop Nrtl treatment and would be followed up for additional 48 weeks.

About Hepatitis B

Hepatitis B viral infection is one of the world's most significant infectious disease threats with more than 290 million people infected globally.^[1] Chronic HBV infection is the leading cause of liver disease and an estimated 820,000 people die of complications from chronic HBV each year.¹ HBV is of exceptional concern in China, where 87 million people are infected.^[2]

About BRII-179 (VBI-2601)

BRII-179 (VBI-2601) is a novel recombinant protein-based HBV immunotherapeutic candidate that expresses the Pre-S1, Pre-S2, and S HBV surface antigens, and is designed to induce enhanced and broad B-cell and T-cell immunity. BRII-179 is currently being investigated in two Phase 2 clinical trials in combination with BRII-835 (VIR-2218) and PEG-IFNα as part of a potential functional cure regimen for the treatment of chronic HBV infection.

About Brii Bio

Brii Biosciences Limited ("Brii Bio", stock code: 2137.HK) is a commercial stage biotechnology company developing therapies to address major public health challenges where patients experience high unmet medical needs, limited choice and significant social stigmas. With a focus on infectious and central nervous system diseases, the Company is advancing a broad pipeline of unique therapeutic candidates with lead programs against hepatitis B viral infection (HBV), postpartum depression (PPD), and major depressive disorder (MDD). The Company is led by a visionary and experienced leadership team and has operations in key biotech hubs, including Raleigh-Durham, the San Francisco Bay Area, Beijing and Shanghai. For more information, visit www.briibio.com.

SOURCE Brii Biosciences Limited