DURHAM, N.C., BEIJING, CHINA, SAN FRANCISCO, Ca., CAMBRIDGE, Mass. April 21, 2021 – Brii
Biosciences (Brii Bio), Vir Biotechnology, Inc. (Nasdaq: VIR), and VBI Vaccines Inc. (Nasdaq: VBIV)
today announced that the first patient has been dosed in a Phase 2 clinical trial evaluating
BRII-835 (VIR-2218), an investigational small interfering ribonucleic acid (siRNA) targeting
hepatitis B virus (HBV), in combination with BRII-179 (VBI-2601), an investigational HBV
immunotherapeutic, for the treatment of chronic HBV infection. This is the first clinical trial in
the field to evaluate the combination of these two HBV mechanisms of action.  

The multi-center, randomized, open-label study is designed to evaluate the safety and efficacy of
BRII-835 (VIR-2218) compared to the combination of BRII-835 (VIR-2218) and BRII-179 (VBI-2601) with
and without interferon-alpha as a co-adjuvant. Both agents have demonstrated proof of mechanism in
HBV patients (NCT04507269 BRII-835
China study and ACTRN12619001210167
BRII-179 APEC study). Brii Bio has led the design and implementation of this functional cure
proof-of-concept study with the support of VIR and VBI, and is the sponsor of the Phase 2 study
( NCT04749368). It will be
conducted at sites in Australia, China, Taiwan, Hong Kong Special Administrative Region of China,
South Korea, New Zealand, Singapore, and Thailand.

Li Yan, M.D., Ph.D., chief medical officer of Brii Bio, said: “Sustained seroclearance of HBV
surface antigen, also known as a functional cure, occurs rarely in the natural history of HBV
infection or during the current standard of care treatment. We believe that both viral antigen
knockdown with BRII-835 (VIR-2218) and sustained induction of HBV-specific host immune responses by
BRII-179 (VBI-2601) are required to remove viral immunosuppression and subsequently break immune
tolerance. The  combination of these two agents is a step toward developing a functional cure for
HBV.” 

Phil Pang, M.D., Ph.D., chief medical officer of Vir, said: “This new combination trial represents
an important addition to our HBV portfolio approach of combining VIR-2218 with various
immunomodulators, including pegylated interferon alpha, VIR-3434 and with a TLR8 agonist, via our
previously announced collaboration with Gilead. We look forward to determining if such combinations
can stimulate an effective immune response that may result in a finite duration of treatment.”

Francisco Diaz-Mitoma, M.D., Ph.D., VBI’s chief medical officer, said: “We believe that a
functional cure for HBV is possible, and will require restoration of HBV-specific immunologic
control in addition to viral suppression mechanisms. Data from our previous study suggest BRII-179
(VBI-2601) was able to restimulate both antibody and T cell responses specific to HBV. This
combination study represents the first combination of a therapeutic HBV vaccine to restore
HBV-immunity with antivirals designed to reduce the levels of HBV surface antigens. We look
forward to seeing the outcome of the trial, a milestone that will be meaningful in our collective
efforts to provide an effective solution for patients with such a complex and highly infectious
virus.”

About BRII-835 (VIR-2218)
BRII-835 (VIR-2218) is an investigational subcutaneously administered HBV-targeting siRNA that has
the potential to stimulate an effective immune response and have direct antiviral activity against
HBV. It is the first siRNA in the clinic to include Enhanced Stabilization Chemistry Plus (ESC+)
technology to enhance stability and minimize off-target activity, which potentially can result in an
increased therapeutic index. VIR-2218 is the first asset in the Company’s collaboration with Alnylam
Pharmaceuticals, Inc. to enter clinical trials. Brii Bio licensed exclusive rights to develop and
commercialize VIR-2218 for the greater China territory from Vir in 2020.

In addition to the Phase 2 combination trial with BRII-179 (VBI-2601), VIR-2218 is being evaluated
in two ongoing trials: as a monotherapy for HBV, and in combination with pegylated interferon-alpha
(PEG-IFN-α). Two additional Phase 2 trials of VIR-2218 are expected to start in 2021.

About BRII-179 (VBI-2601)
VBI-2601 (BRII-179) is a novel recombinant, protein-based HBV immunotherapeutic candidate that
builds upon the 3-antigen conformation of VBI’s prophylactic 3-antigen HBV vaccine candidate, and is
designed to target enhanced B-cell and T-cell immunity. VBI-2601 (BRII-179) is being developed in
collaboration with Brii Biosciences in the licensed territory of China, Hong Kong, Macau, and Taiwan
as part of a potential functional cure for chronic hepatitis B infection.

About Brii Biosciences
Brii Biosciences (Brii Bio) is a multi-national company committed to serving patients' needs and
improving public health by accelerating the development and delivery of breakthrough medicines
through partnerships, best-in-class research and development, and the disruptive application of
digital and data insight. With operations in the People's Republic of China and the United States,
Brii Bio is poised to serve as a bridge to carry transformative medicines to patients, help create
significant growth for our partners and establish an innovation engine to help improve the public
health and wellbeing of patients around the world. Brii Bio is developing treatments for illnesses
with significant public health burdens, including infectious diseases, liver diseases, and CNS
diseases. For more information, visit www.briibio.com.

About Vir Biotechnology
Vir Biotechnology is a clinical-stage immunology company focused on combining immunologic insights
with cutting-edge technologies to treat and prevent serious infectious diseases. Vir has assembled
four technology platforms that are designed to stimulate and enhance the immune system by exploiting
critical observations of natural immune processes. Its current development pipeline consists of
product candidates targeting COVID-19, hepatitis B virus, influenza A and human immunodeficiency
virus. For more information, please visit www.vir.bio.

About VBI Vaccines Inc. 
VBI Vaccines Inc. (“VBI”) is a biopharmaceutical company driven by immunology in the pursuit of
powerful prevention and treatment of disease. Through its innovative approach to virus-like
particles (“VLPs”), including a proprietary enveloped VLP (“eVLP”) platform technology,
VBI develops vaccine candidates that mimic the natural presentation of viruses, designed
to elicit the innate power of the human immune system.  VBI is committed to targeting and
overcoming significant infectious diseases, including hepatitis B, coronaviruses, and
cytomegalovirus (CMV), as well as aggressive cancers including glioblastoma (GBM).  VBI is
headquartered in Cambridge, Massachusetts, with research operations in Ottawa, Canada, and a
research and manufacturing site in Rehovot, Israel. For more information, please visit www.vbivaccines.com.

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