Topline Data from Phase 2b Studies Inform HBV Functional Cure Strategy; Additional Data Expected in 2H 2026

Emerging Discovery Programs Build Momentum

BRII-5395 mRNA Cancer Vaccine Moving into Clinical Evaluation for HCC

Strong Cash Position Supports Continued Strategic Execution

Conference Call Scheduled: August 21 at 8:30 a.m. HKT

DURHAM, N.C. and BEIJING, Aug. 20, 2026 /PRNewswire/ — Brii Biosciences Limited (“Brii Bio,” or the “Company,” stock code: 2137.HK), a biotechnology company developing therapies to improve patient health and choice across diseases with high unmet medical need, today provided a corporate update and reported its financial results for the six-month period ended June 30, 2026.

In the first half of 2026, Brii Bio generated additional clinical data supporting its differentiated hepatitis B virus (HBV) functional cure strategy while continuing to expand its internal discovery capabilities and advance its RNA-based technology platforms.

In its HBV clinical program, the Company presented end-of-study data from its Phase 2 ENSURE study at the European Association for the Study of the Liver (EASL) Congress 2026. On July 3, the Company also announced topline end-of-treatment data from its Phase 2b ENRICH and ENHANCE studies. To date, findings across the ENSURE, ENRICH and ENHANCE studies have consistently supported the potential of BRII-179 to improve functional cure outcomes as part of a combination regimen. Detailed data from the ENRICH and ENHANCE studies are expected to be presented in the second half of 2026.

Beyond its HBV portfolio, the Company continued to advance its internal discovery capabilities and invest in the development of RNA-based technology platforms. Subsequent to the reporting period, the first participant was dosed in a clinical study evaluating BRII-5395, an internally discovered mRNA therapeutic vaccine for advanced hepatocellular carcinoma (HCC). This milestone represents the first clinical evaluation of an RNA-based therapeutic originating from Brii Bio’s internal discovery efforts. While BRII-5395 is an mRNA therapeutic vaccine, the Company’s broader RNA platforms encompass multiple RNA modalities. During the first half of 2026, Brii Bio progressed multiple internally discovered candidates across various stages of discovery and preclinical development, including programs that extend the application of its technology platforms into additional therapeutic areas beyond infectious diseases.

With effective cost control measures and optimized operating structure in place, Brii Bio remains well-capitalized, with a cash position of approximately US$260 million as of June 30, 2026, providing financial flexibility to support its late-stage HBV programs and early discovery initiatives.

“Our progress in the first half of the year reflects meaningful advances across both our late-stage HBV portfolio and our expanding discovery capabilities,” said Dr. Zhi Hong, Chairman and Chief Executive Officer of Brii Bio. “Data generated across our HBV studies continue to inform our functional cure strategy. At the same time, the initiation of clinical evaluation for BRII-5395 demonstrates our ability to translate internal discovery into pipeline assets. We look forward to sharing additional milestones later this year. Together, these efforts are building a more diversified pipeline and strengthening the foundation for sustainable innovation and long-term value creation.”

Corporate and Clinical Updates

HBV Program

Brii Bio continued to advance its HBV pipeline with a focus on achieving higher functional cure rates through novel combination regimens. The Company’s differentiated HBV portfolio, including BRII-179, a recombinant protein-based HBV immunotherapeutic, and elebsiran, an HBV-targeting siRNA, has generated a growing body of clinical data supporting Brii Bio’s functional cure strategy through the completed Phase 2b ENSURE study and ongoing ENRICH and ENHANCE Phase 2b studies.

• The Phase 2b ENSURE study was designed to assess the safety and efficacy of combination approaches aimed at improving functional cure outcomes. Cohorts 1-3 evaluated elebsiran in combination with PEG-IFNα compared to PEG-IFNα monotherapy. Cohort 4 evaluated the potential role of BRII-179 in enhancing immune responsiveness and improving hepatitis B surface antigen (HBsAg) loss rates. In the first half of 2026, end-of-study data from Cohorts 1-4 of the Phase 2 ENSURE study were presented at EASL 2026, demonstrating that:
  • The HBsAg loss benefit observed in the elebsiran and PEG-IFNα combination cohorts resulted in a higher functional cure rate compared to the PEG-IFNα alone cohort.
  • BRII-179-experienced participants achieved higher functional cure rates, particularly among anti-HBs responders, suggesting that BRII-179 may play an important role in achieving durable immunological control of HBV. 
• To further define the role of BRII-179 in HBV treatment and identify an optimal combination regimen for potential registrational development, the Company is evaluating BRII-179 in two additional ongoing Phase 2b studies: ENRICH and ENHANCE studies.

  The ENRICH study evaluates BRII-179 as a priming therapy administered prior to elebsiran and PEG-IFNα treatment. The ENHANCE study evaluates a concurrent triple combination regimen of BRII-179, elebsiran, and PEG-IFNα to enhance the functional cure rates. In July, the Company announced topline end-of-treatment data from its Phase 2b ENRICH and ENHANCE studies.

  • At EOT, the ENRICH study evaluating pre-treatment with BRII-179 followed by elebsiran and PEG-IFNα achieved HBsAg loss rates of 42.9% (42/98) and 40.0% (20/50) across two BRII-179 dosing schedules (five doses administered every 3 weeks and 7 doses administered every 2 weeks, respectively). These results were consistent with the 41.9% (13/31) HBsAg loss rate observed in ENSURE Cohort 4 among patients previously treated with BRII-179, supporting the potential immune-priming role of BRII-179.
  • Subgroup analyses from the ENRICH study suggest potential differentiation in subjects with higher baseline HBsAg levels (1000-3000 IU/mL) comparing with other HBV functional cure regimens under development by other companies, consistent with prior findings from ENSURE Cohort 4, indicating that BRII-179 may induce beneficial immune responses regardless of baseline HBsAg levels in this difficult-to-treat population.
  • At EOT, the ENHANCE (Part A-1) study evaluating a concurrent triple combination did not demonstrate improved HBsAg loss rates compared with ENSURE Cohorts 2 and 3, 29.7% (11/37), with an observed rate of 25.5% (25/98). Higher HBsAg loss rates, however, were observed compared with the PEG-IFNα control arm, 10.2% (5/49).
  • The ENHANCE study also evaluated a sequential approach designed to potentially shorten PEG-IFNα therapy in its Part A-2 by administering BRII-179 plus elebsiran during the first 24 weeks followed by 24 weeks of elebsiran and PEG-IFNα. At EOT, this combination regimen achieved an HBsAg loss rate of 22.5% (18/80), suggesting that a full course of PEG-IFNα therapy may be important for achieving optimal functional cure outcomes.

No new safety concerns have been identified across ENSURE, ENRICH and ENHANCE to date.

On August 19, 2026, the Company received an email notification from one of its central laboratory service providers of a product recall involving a commercial assay kit^[1] used for HBsAg testing in the ENHANCE study. Based on the information currently available and the Company’s preliminary assessment, the potential impact on the clinical data of the Company’s sponsored trials publicly disclosed to date appears limited to the EOT HBsAg data for Part A-2 of the ENHANCE study. The Company is working with the service provider to identify potentially affected samples and arrange retesting using unaffected assay kits. Subject to completion of the retesting and further analysis, as at the date of this announcement, the Company has not identified any indication at this stage that the matter would materially affect its overall interpretation of the study results or the program development decisions announced to date. The Company will continue to evaluate the matter and provide updates as appropriate if any material developments arise.

The Company plans to present detailed data from the ENRICH and ENHANCE studies, including additional efficacy, safety and subgroup analyses, at a scientific conference in the second half of 2026.

Discovery Program Update

Brii Bio is expanding its RNA platforms beyond infectious diseases into new therapeutic areas. In the first half of 2026, the Company progressed multiple early-stage candidates spanning various stages of discovery and pre-clinical development, with a focus on generating differentiated therapeutic opportunities in diseases with significant unmet medical needs.

• BRII-5395 is a novel mRNA therapeutic vaccine internally developed by Brii Bio. It is being evaluated as part of a combination immunotherapy approach for HBV-related HCC.
  • On August 12, 2026, subsequent to the reporting period, the first participant was dosed in a clinical study evaluating BRII-5395 in participants with advanced HCC. The study, conducted at the Cancer Hospital of the Chinese Academy of Medical Sciences, is designed to evaluate the safety, tolerability, immunogenicity and preliminary anti-tumor activity of BRII-5395 in combination with an anti-PD-1 antibody and an anti-VEGF antibody. The current standard of care of immune checkpoint inhibitors have limited efficacy against HCC.
  • As the first internally developed mRNA-based cancer therapeutic vaccine from Brii Bio to enter clinical evaluation, BRII-5395 represents an important milestone in the advancement of the Company’s internal discovery capabilities and RNA-based technology platform.

While BRII-5395 is an mRNA therapeutic vaccine, the Company’s broader RNA platforms encompass multiple RNA modalities. In addition, the Company has extended the application of its technology platforms into additional therapeutic areas beyond infectious diseases.

Further program updates are expected throughout the remainder of 2026. The Company is actively exploring partnership opportunities to advance selected discovery programs to maximize the value of its emerging pipeline.

Additional Clinical Programs

• Brii Bio is actively seeking strategic partnerships for long-acting anti-HIV and multidrug resistant (MDR) antibacterial therapeutic candidates to maximize the development and commercialization potential.

Other Corporate Updates

On April 16, 2026, the Company and Brii Biosciences Offshore Limited, a subsidiary of the Company, submitted a Demand for Arbitration to the United States-based Judicial Arbitration and Mediation Services, Inc. against Vir Biotechnology, Inc. (the “Arbitration”).

The Company announced the commencement of the Arbitration on April 16, 2026 and provided a further update on May 22, 2026. As of June 30, 2026, the Arbitration remained in its early stages, and the parties had not reached a resolution of the claims.

In light of the ongoing arbitration, the Company is not currently advancing elebsiran into Phase 3 development and future development plans for elebsiran remain under evaluation pending resolution of the Arbitration. The Company will continue to monitor developments and update shareholders as appropriate.

Outlook

Looking ahead, the Company remains focused on advancing its differentiated HBV portfolio while continuing to progress its RNA-based discovery efforts.

The Company plans to continue investing in its internal discovery capabilities and RNA platform to support the advancement of future pipeline candidates. Through these efforts, Brii Bio aims to generate new therapeutic opportunities and build a sustainable pipeline of innovative medicines addressing diseases with significant unmet medical needs.

With a strong balance sheet and disciplined execution, Brii Bio is well positioned to pursue value-creating opportunities and deliver on its strategic priorities.

Interim 2026 Financial Results

• The Company maintains a strong cash position to support its operations through 2029. Our bank deposits and cash and cash equivalents were RMB1,770.8 million as of June 30, 2026, representing a decrease of RMB170.2 million or 8.8% compared with RMB1,941.0 million as of December 31, 2025. The decrease was primarily due to payout of research and development activities and daily operations.
• Through pipeline prioritization, resource optimization, internalization of certain clinical development activities, and cost-saving measures of third-party vendors, we have effectively controlled our operational expenses. Research and development expenses were RMB98.3 million for the six months ended June 30, 2026, representing a decrease of RMB18.7 million or 16.0%, compared with RMB117.0 million for the six months ended June 30, 2025. The decrease was primarily attributable to organizational optimization, compensation framework adjustments, and lower third-party contracting costs as Phase 2 study activities for the HBV programs wound down, partially offset by increased investment in early-stage discovery.
• Administrative expenses were RMB52.6 million for the six months ended June 30, 2026, representing a decrease of RMB5.6 million or 9.6%, compared with RMB58.2 million for the six months ended June 30, 2025. The decrease primarily reflected lower employee costs following organizational optimization and adjustments to the senior management compensation framework, partially offset by the increase in professional fees and the depreciation and amortization cost.
• Other income was RMB19.5 million for the six months ended June 30, 2026, representing a decrease of RMB8.6 million or 30.6%, compared with RMB28.1 million for the six months ended June 30, 2025. This was mainly due to the decrease in bank interest income of RMB7.9 million attributable to the declining interest rates on time deposits.

Conference Call Information

The Company will host a live conference call in Chinese on August 21 at 8:30 a.m. HKT (8:30 p.m. ET on August 20). For the registration link, please click here.

All participants shall use the link provided above to complete the online registration process prior to the conference call. A replay of the conference call will be available after the call and can be accessed by visiting the Company’s website at www.briibio.com under the Investor Relations section.

This press release contains references to third-party information. Such information is not deemed to be incorporated by reference in this press release. Brii Bio disclaims responsibility for such third-party information.

About Brii Bio

Brii Biosciences Limited (“Brii Bio”, stock code: 2137.HK) is a biotechnology company developing therapies to improve patients’ health by addressing high unmet medical needs with limited treatment options. The Company is advancing a broad pipeline of unique therapeutic candidates with lead programs against hepatitis B virus (HBV) infection. The Company is led by a visionary and experienced leadership team and has operations in both China and the United States. For more information, visit www.briibio.com.

Forward-Looking Statement

The information communicated in this press release contains certain statements that are or may be forward-looking. These statements typically contain words such as “will,” “expects,” “believes,” “plans” and “anticipates,” and words of similar import. By their nature, forward-looking statements involve risk and uncertainty because they relate to events and depend on circumstances that will occur in the future. There may be additional material risks that are currently not considered to be material or of which the Company is unaware. These forward-looking statements are not a guarantee of future performance. Against the background of these uncertainties, readers should not rely on these forward-looking statements. The Company assumes no responsibility to update forward-looking statements or to adapt them to future events or developments.

 

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SOURCE Brii Biosciences Limited