DURHAM, N.C., United States and BEIJING, China – May 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, and TSB Therapeutics (Beijing) Co., Ltd. (“TSB Therapeutics”), a joint venture majority-owned by the Company, today announced that the Beijing Municipal Medical Products Administration (the “Beijing MMPA”) officially issued conclusions following the Good Manufacturing Practice (GMP) compliance inspections of the manufacturing sites of the Company’s contract development and manufacturing organization (CDMO), WuXi AppTec Biopharmaceuticals Co., Ltd. and WuXi Biologics (Shanghai) Co., Ltd., for the drug substances and drug products of the Company’s COVID-19 neutralizing antibodies, amubarvimab and romlusevimab.

The conclusions state that the production of amubarvimab and romlusevimab meet the requirements of the Good Manufacturing Practise (2010 Revision) of China and its appendix in material aspects. The Company will be allowed to launch the commercial manufacturing and sales of the amubarvimab/romlusevimab combination once further risk control and the required rectification are completed in cooperation with its CDMO. GMP compliance inspection is the last regulatory requirement prior to the commercialization of the amubarvimab/romlusevimab combination. The Company will work closely with the relevant regulatory authorities and key partners to determine our next steps.

In addition, live virus and pseudovirus testing data from multiple independent labs demonstrate that patients receiving intravenous 1000mg/1000mg amubarvimab/romlusevimab combination should retain neutralizing activity against Omicron BA.2 subvariant and all previous variants of concern.

Since the emergence of the COVID-19 pandemic in 2020, Brii Bio has cooperated with the Third People’s Hospital of Shenzhen and Tsinghua University to invest significant resources for the development of amubarvimab and romlusevimab. With the Company’s strong R&D capabilities and critical international partnerships, the clinical development of the amubarvimab/romlusevimab combination has been rapidly advancing in China and globally. In less than 20 months, Brii Bio progressed the amubarvimab/romlusevimab combination from discovery to completion of Phase 3 in the global clinical trial leading to rapid approval by the China NMPA.

The Company has collaborated with its CDMO to expand the production of the therapy in order to rapidly benefit the patients in need once the amubarvimab/romlusevimab combination’s clinical effectiveness is validated. To date, Brii Bio has cooperated with local Chinese governmental agencies and hospitals to donate nearly 3,000 doses of the amubarvimab/romlusevimab combination for emergency use in 22 hospitals in 21 cities. Nearly 1,000 patients received the treatment including patients with mild, common, severe and critical illnesses, with the oldest patient being 92 years old which effectively controlled the outbreak of Delta variant. After the successful Phase 3 clinical trial, Brii Bio also invested additional funds and resources to promote the regulatory application and commercialization of the amubarvimab/romlusevimab combination, striving to bring this clinically proven effective treatment option to more patients worldwide.

About Long-Acting COVID-19 Neutralizing Antibody Therapy, Amubarvimab/Romlusevimab Combination

Amubarvimab and Romlusevimab are non-competing SARS-CoV-2 monoclonal neutralizing antibodies derived from convalesced COVID-19 patients developed in collaboration with the 3rd People’s Hospital of Shenzhen and Tsinghua University. They have been specifically engineered to reduce the risk of antibody-dependent enhancement and prolong the plasma half-lives for potentially more durable treatment effect.

Based on the final results from the U.S. National Institutes of Health (NIH)-sponsored ACTIV-2 Phase 3 clinical trial with 837 enrolled outpatients, the amubarvimab/romlusevimab combination demonstrates a statistically significant 80% reduction of hospitalization and death with fewer deaths through 28 days in the treatment arm (0) relative to placebo (9), and improved safety outcome over placebo in non-hospitalized COVID-19 patients at high risk of clinical progression to severe disease. Similar efficacy rates were observed in participants initiating therapy early (0-5 days) and late (6-10 days), following symptom onset, providing critically needed clinical evidence in COVID-19 patients who were late for treatment.

The live virus testing data as well as pseudovirus testing data from multiple independent labs demonstrates that the amubarvimab/romlusevimab combination retains activity against major SARS-CoV-2 variants of concern, including the following commonly identified variants, B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.429 (Epsilon), B.1.617.2 (Delta), AY.4.2 (Delta Plus), C.37 (Lambda), B.1.621 (Mu), B.1.1.529-BA.1 (Omicron), and BA.1.1 and BA.2 (Omicron subvariants).

About Brii Bio

Brii Biosciences Limited (“Brii Bio”, 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.

About TSB Therapeutics

TSB Therapeutics (Beijing) Co., Ltd. (“TSB Therapeutics”, or the “Company”) is a holding company of Brii Bio. TSB Therapeutics was jointly established in Beijing in May 2020 by Brii Bio, the 3rd People's Hospital of Shenzhen and Tsinghua University. The Company is committed to developing the amubarvimab/romlusevimab combination. TSB Therapeutics holds exclusive rights to develop and commercialize the amubarvimab/romlusevimab combination in Greater China.

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