Brii Bio Presents New Data on BRII-835 (VIR-2218) in Chinese Patients with Chronic Hepatitis B at APASL 2022

New data demonstrate BRII-835 (VIR-2218) was well tolerated with notable reductions in serum HBsAg observed in the Chinese patients infected with chronic hepatitis B

DURHAM,N.C. and BEIJING,March 31,2022 --Brii Biosciences Limited("Brii Bio" or the "Company",stock code: 2137.HK) a multi-national company developing innovative therapies for diseases with significant unmet medical needs and large public health burdens,today presented new data from a Phase 2 randomized,double-blind,placebo-controlled trial of BRII-835 (VIR-2218) in Chinese patients with chronic hepatitis B virus (HBV) infection,at the 31st Conference of Asian Pacific Association for the Study of the Liver (APASL) 2022,taking place virtually from March 30 to April 3 in Seoul,South Korea.

The data demonstrate that BRII-835 (VIR-2218),an investigational small interfering ribonucleic acid (siRNA) that mediates RNA interference (RNAi),results in dose-dependent reduction in hepatitis B surface antigen (HBsAg) in Chinese patients with chronic HBV infection who received two doses of BRII-835 (VIR-2218). Similar HBsAg reductions were observed in both HBeAg- and HBeAg+ patients. In addition,BRII-835 (VIR-2218) was well-tolerated,with all treatment emergent adverse events (TEAEs) reported as mild or moderate,and no clinically significant alanine transaminase (ALT) elevations were observed.

"The dose-dependent reduction in serum HBsAg observed in both HBeAg- and HBeAg+ Chinese chronic HBV patients in this trial after two doses of BRII-835 (VIR-2218) is consistent with previous findings demonstrated in other racial/ethnic groups," said Dr. Jidong Jia,Professor of Medicineat the Liver Research Centre,Beijing Friendship Hospital,Capital Medical University in Beijing,China. "Supported by these data,we believe that novel agents like BRII-835(VIR-2218)that effectively reduce the high HBV antigen burden has the potential to be the cornerstone of functional cure regimens for patients with chronic HBV infection,thereby facilitating the elimination of this major global public health threat."

"As part of our goal to develop a functional cure for chronic HBV,we are pleased that the data from this trial continue to support the potential of siRNA asthe backbone of combination treatment regimens that are being evaluated in several ongoing trials," said Li Yan,M.D.,Ph.D.,Chief Medical Officer at Brii Bio. "We look forward to seeing more data later this year from these trials in which BRII-835 (VIR-2218)is being investigated in combination with other agents."

Abstract Number:L-OP-1324

Oral Presentation Title:Safety and antiviral activity of two monthly administrations of BRII-835 (VIR-2218),an X-targeting RNAi therapeutic,in Chinese patients with chronic HBV infection

Presenter:Jidong Jia,Professor of Medicine at Capital Medical University and Director of the Liver Research Centre at Beijing Friendship Hospital in Beijing,China

BRII-835 (VIR-2218) was well-tolerated in 16 virally-suppressed Chinese patients with non-cirrhotic chronic HBV infection assigned to receive two doses of monthly subcutaneous injection of BRII-835

12 weeks post last dose,the mean reductions in HBsAg observed in patients who received 50 mg and 100 mg doses of BRII-835 were 1.02 log10 IU/mL and 1.22 log10 IU/mL for HBeAg- patients and 0.70 log10 IU/mL and 1.15 log10 IU/mL for HBeAg+ patients,respectively

In all patients achieving HBsAg decline > 1 log10 IU/mL at 12 weeks post last dose,serum HBsAg remained below baseline through Week 48

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 has 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. Brii Bio licensed exclusive rights to develop and commercialize VIR-2218 for the greater China territory from Vir Biotechnology,Inc. ("Vir") in 2020.

Meanwhile,BRII-835 (VIR-2218) is being investigated in three additional Phase 2 studies,sponsored by Brii and Vir,respectively,in combinations with BRII-179 (a recombinant therapeutic vaccine),PEG-IFN-alpha and/or VIR-3434 (a monoclonal antibody targeting HBV) as a functional cure regimen for chronic HBV infection.

About Hepatitis B

Hepatitis B is one of the world's most significant infectious disease threats,infected more than 290 million people globally and more than 70 millions in China. HBV infection is the leading cause of liver disease,and,with current treatments,it is very difficult to cure,and many patients develop liver cancers. An estimated 780,000 people die each year from complications of chronic HBV,such as liver decompensation and hepatocellular carcinoma.

About Brii Bio

Brii Biosciences Limited ("Brii Bio",or the "Company",stock code: 2137.HK) is a biotechnology company based in China and the United States committed to advancing therapies for significant infectious diseases,such as hepatitis B,COVID-19,human immunodeficiency virus (HIV) infection,multi-drug resistant (MDR) or extensive drug resistant (XDR) gram-negative infections,and other illnesses,such as the central nervous system (CNS) diseases,which have significant public health burdens in China and worldwide. For more information,visit www.briibio.com.