Brii Biosciences Announces Commercial Launch of its Amubarvimab/Romlusevimab Combination Therapy for COVID-19 in China

The Company is working closely with its commercial partners to supply the combination therapy to patients in need

Brii Bio progressed the combination therapy from discovery to global Phase 3 data readout and first regulatory approval by the China NMPA in less than 20 months,validating the Company's R&D expertise and capabilities

DURHAM,N.C. and BEIJING,July 7,2022 --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 the commercial launch of the amubarvimab/romlusevimab combination,a long-acting COVID-19 neutralizing antibody therapy,in China. Today,the first commercial batch of theantibodies was released,marking an important milestone in the commercialization of the combination therapy.

The amubarvimab/romlusevimab combination was approved by China's National Medical Products Administration (NMPA) in December 2021 for the treatment of adults and pediatric patients (age 12-17 weighing at least 40 kg) with mild and normal type of COVID-19 at high risk for progression to severe disease,including hospitalization or death. The indication of pediatric patients (age 12-17 weighing at least 40 kg) is under a conditional approval. InMarch 2022,the National Health Commission of China added the amubarvimab/romlusevimab combination to its COVID-19 Diagnosis and Treatment Guidelines (9th Pilot Edition) ("Guidelines") for the treatment of COVID-19.

On March 21,2022,the National Healthcare Security Administration of China issued a notice to temporarily include the newly added drugs in the Guidelines in reimbursement by the provincial health insurance fund. Since March 22,the Healthcare Security Administrations of various provinces and cities have successively implemented the instructions of the notice and included the amubarvimab/romlusevimab combination into the reimbursement of the local health insurance fund.

"We're proud to bring the first locally-discovered and approved COVID-19 treatment in China to patients in need with the support and guidance of relevant government authorities. The global Phase 3 clinical trial demonstrated clear patient benefit with 80% reduction of hospitalization and death. In addition,the livevirus and pseudovirus testing data from multiple independent labs demonstrate that the amubarvimab/romlusevimab combination retains neutralizing activity against the live Omicron BA.2 subvariants prevalent in China and all previous variants of concern. These accomplishments reinforce Brii Bio's scientific expertise in infectious disease and underscore our mission to tackle the biggest public health challenges with breakthrough innovation and insight. Our employees are the heroes who have given their all to achieving this great honor," said Rogers Luo,President and General Manager,Greater China of Brii Bio,and Chief Executive Officer of TSB Therapeutics. "Our first priority will be to coordinate with our commercial partners to manage the distribution of the amubarvimab/romlusevimab combination in China to patients with the highest unmet need for our novel treatment to protect peoples' lives."

In 2021,Brii Bio donated nearly 3,000 doses of the amubarvimab/romlusevimab combination for emergency use in 22 hospitals in 21 cities as part of its commitment to ensurehumanitarian access and to help curb the outbreaks of the delta variants.

"Despite the progress being made with vaccines,the pandemic continues to affect the health of communities in China,and we believe—based on the clinical data generated in partnership with top-tier global research institutions—that the amubarvimab/romlusevimab combination treatment has the potential to bring significant clinical benefit to patients in need and support communities under threat of SARS-CoV-2 infection," said Qing Zhu,Ph.D.,Senior Vice President,Head of Biopharmaceutical Research of Brii Bio. "When we made the decision to invest significant resources and expertise in the fight against COVID-19,we knew this would be a considerable undertaking and we must play our part. We could not have made it to this point of bringing our much-needed medicine to patients throughout China without the support of our world-class partners and we look forward to continuing to work with stakeholders across the industry to enable the timely distribution of the combination therapy to healthcare providers and patients."

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)/National Institute of Allery and Infectious Diseases (NIAID)-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 have demonstrated 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). Additional testings including live virus assays are being conducted to confirm the neutralizing activity against BA.4/5 and BA.2.12.1.

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.