Brii Biosciences Provides Latest Clinical Development and Corporate Updates

Company extends BRII-179 license to global rights and introduces preventive vaccine,PreHevbri® in Greater China and Asia Pacific markets

New data from BRII-835 + PEG-IFN-α study have demonstrated that robust anti-HBs antibody responses at the end of treatment are associated with sustained HBsAg loss 24 weeks post treatment

Company owns exclusive global rights of BRII-693 in development for difficult-to-treat carbapenem-resistant Gram-negative bacterial infections

Dr. David Margolis appointed as Chief Medical Officer to lead organization's late-stage clinical programs towards commercialization

DURHAM,N.C. and BEIJING,July 6,2023 -- 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 need,today provided updates on its diverse pipeline of infectious disease (ID) and central nervous system (CNS) disease candidates and announced a pivotal leadership transition that will further advance its strategic priorities.

"We are proud to announce our latest achievements in advancing our mission to improve patient health and address critical public health issues. With expanded collaborations and acquisitions,including the worldwide license extension of BRII-179,the introduction of PreHevbri® vaccine in Greater China and Asia Pacific markets,and the acquisition of global rights for BRII-693,we are making remarkable progress in our infectious disease portfolio," said Zhi Hong,Ph.D.,Chairman and Chief Executive Officer of Brii Bio. "Additionally,it is with great pleasure that I introduce Dr. David Margolis as our new Chief Medical Officer. With his extensive experience and expertise both as a licensed ID specialist and a drug developer,Dr. Margolis will play a pivotal role in leading the successful execution of our late-stage clinical programs towards commercialization. Together,these strategic moves align seamlessly with our growth plans and represent important progress for our broader global strategy."

Core Clinical Development Updates

Hepatitis B Virus (HBV)

Led by Brii Bio's team in China and partners,Vir Biotechnology,Inc. ("Vir," NASDAQ: VIR) and VBI Vaccines,Inc. ("VBI," NASDAQ: VBIV),the Company is addressing the full range of disease impact for HBV by progressing multiple combination studies to achieve a best-in-class functional cure in broad patient populations,as well as to commercialize a prevention vaccine in Greater China and Asia Pacific region. China and many Asia Pacific countries have the highest prevalence of HBV globally,with over 150 million people impacted by this disease (China ~86 million,Southeast Asia ~69 million HBsAg positive population1). Currently,there is no effective HBV functional cure available,highlighting the urgent need for a better prophylactic vaccine.

In July 2023,Brii Bio announced substantial expansion of its HBV portfolio in collaboration with VBI. Under the terms of the agreements,Brii Bio extends its exclusive license to worldwide markets for BRII-179 (VBI-2601). Additionally,Brii Bio also acquires exclusive rights to develop and commercialize PreHevbri® in Greater China and Asia Pacific countries including Australia,Indonesia,Malaysia,New Zealand,Philippines,Singapore,South Korea,Thailand and Vietnam,among others. PreHevbri® is a clinically differentiated 3-antigen adult HBV prophylactic vaccine recently approved for use in the United States,European Union/European Economic Area,United Kingdom,Canada,and Israel.

In June 2023,Vir and VBI presented multiple clinical study results at the European Association for the Study of the Liver (EASL) Congress™ 2023:

In follow-up data from Vir's Phase 2 trial of combination 24 or 48 weeks of VIR-2218 (BRII-835) on top of a course of up to 48 weeks of pegylated interferon alpha (PEG-IFN-α),16% (5/31) of participants demonstrated sustained HBsAg loss 24 weeks after end of treatment. Anti-HBs titers greater than 500 mIU/mL at the end of treatment were associated with sustained HBsAg loss at 24 weeks after the end of treatment.

Data from Part A of Vir's Phase 2 MARCH trial evaluating short treatment duration of combinations of VIR-2218 (BRII-835) and VIR-3434 (BRII-877) in chronic HBV participants demonstrated a 2.7-3.1 log10 IU/mL decline in HBsAg levels and 90% of participants achieved HBsAg reduction below 10 IU/mL at the end of treatment.

VBI presented follow-up data in a subset of participants from the pivotal Phase 3 study,PROTECT,up to 3.5 years after completion of immunization with PreHevbrio® (also known as PreHevbri® in the European Union/European Economic Area and United Kingdom,and Sci-B-Vac® in Israel),a prophylactic 3-antigen HBV vaccine. The mean anti-HBs titers in participants vaccinated with PreHevbrio® were more than 5x higher than those vaccinated with Engerix-B (1287 vs. 254 mIU/mL) suggesting that T-cell responses of PreHevbrio® may contribute to long lasting and strong humoral immune responses and greater durability compared with Engerix-B.

In May 2023,Brii Bio submitted an IND application to the NMPA of China for the development of BRII-877 (VIR-3434),and a Phase 1 clinical study is expectedto start by the end of 2023.

In the second half of 2023,the Company expects data readouts from two Phase 2 trials:

Additional data from the Phase 2 study evaluating BRII-835 (VIR-2218) and BRII-179 (VBI-2601) combination.

Topline results from the Phase 2 study evaluating BRII-179 (VBI-2601) in combination with PEG-IFN-α.

Brii Bio plans for additional combination studies with the earliest to start in 2H 2023.

Postpartum Depression (PPD) and Major Depressive Disorder (MDD)/Other CNS Disorders

Brii Bio is developing its internally-discovered BRII-296 therapeutic candidate as a first-of-its-kind one-time injection treatment with the potential to expand the PPD and MDD treatment landscapes for patients in the U.S.

In June 2023,Brii Bio announced the dosing of the first subject in a Phase 1 clinical trial for BRII-297,a long-acting injectable (LAI) being developed to treat anxiety and depressive disorders. The study,currently underway,aims to evaluate the safety,tolerability,and pharmacokinetics of BRII-297 in healthy volunteers.

Brii Bio is working closely with the U.S. Food and Drug Administration (FDA) to align and agree on a PPD treatment protocol in preparation for its Phase 2 proof-of-concept (POC) study to be initiated in the second half of 2023.

Brii Bio is actively working to expand the clinical indications for BRII-296 and plans to initiate additional studies in the U.S. in 2024.

Additional Pre-Clinical and Clinical Development Updates

Human Immunodeficiency Virus (HIV) Infection

In December 2022,Brii Bio successfully lifted the U.S. FDA clinical hold,enabling the conduct of the Company's planned Phase 1 study to investigate a lower oral dose of once-weekly BRII-732,with dosing initiated in 2Q 2023.

The Company is exploring partnership opportunities to continue developing BRII-732 as part of a potential oral,once-weekly,long-acting combination treatment option for HIV patients.

The Company is pursuing partnership opportunities for BRII-753 as part of a long-acting,subcutaneous injection with potential for dosing once monthly,once quarterly,or twice-yearly combination treatment option for HIV patients.

MDR/XDR Gram-Negative Bacteria Infections

In June 2023,Brii Bio announced definitive agreements with Qpex Biopharma ("Qpex") to acquire exclusive global rights of BRII-693 (QPX-9003),expanding its existing rights in Greater China. The Company returns its exclusive rights of BRII-636 (QPX-7728 or OMNIvance) and BRII-672 (QPX-7831 or ORAvance) in Greater China to Qpex in connection with the acquisition of Qpex by Shionogi.

In April 2023,Brii Bio submitted a pre-IND to the NMPA of China for the development of BRII-693 in China. BRII-693 has a highly differentiated safety and efficacy profile to address the most difficult-to-treat Acinetobacter baumannii and Pseudomonas aeruginosa infections resistant to carbapenem.

Nontuberculosis Mycobacteria (NTM) Lung Disease

Brii Bio's partner,AN2 Therapeutics,Inc. ("AN2," NASDAQ: ANTX) is enrolling its Phase 2/3 pivotal trial evaluating once-daily,oral epetraborole (BRII-658) for treatment-refractory MAC lung disease. AN2 reported in May that there were nearly 80 sites active in its pivotal Phase 2/3 trial of epetraborole in treatment-refractory MAC lung disease.

Corporate Update

Dr. DavidMargolis has been appointed Chief Medical Officer (CMO) after serving as Brii Bio's Head of Infectious Diseases Therapy Area for nearly three years. As the CMO,Dr. Margolis will play a critical role in the Company's late-stage clinical development towards commercial growth across the pipeline. In addition,he will continue to fulfill existing responsibilities that he previously held as Head of Infectious Diseases Therapy Area. Meanwhile,Dr. Li Yan will leave the company to pursue other interests. Brii Bio expresses sincere gratitude to Dr. Yan for his contributions to the Company in the past 5 years.

About Brii Bio

Brii Biosciences is a biotechnology company developing therapies to address some of the world's most common diseases 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 to develop a novel functional cure for hepatitis B viral infection (HBV) and first-of-its-kind treatment options for 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.

1Lancet Gastroenterol Hepatol. 2018; 3(6): 383-403