Brii Bio Announces that National Health Commission of China Adds Amubarvimab/Romlusevimab Combination to its COVID-19 Diagnosis and Treatment Guidelines (9th Pilot Edition)

The amubarvimab/romlusevimab combination is the first locally-discovered and approved SARS-CoV-2 target-specific treatment in China,through a randomized,double-blind and placebo-controlled trial

In vitro tests shows that amubarvimab/romlusevimab combination retains neutralizing activity against the Omicron variant and other variants of concern such as Delta and Delta Plus

DURHAM,N.C.,and BEIJING,March 16,2022 --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 announced that the National Health Commission of China added the Company's neutralizing monoclonal antibody (mAb) therapy,the amubarvimab/romlusevimab combination,to its COVID-19 Diagnosis and Treatment Guidelines (9th Pilot Edition) for the treatment of COVID-19,marking a critical breakthrough in COVID-19 therapeutic drugs.

"Inclusion of Brii Bio's combination therapy in the latest COVID-19 treatment guidelines reflects the national healthcare authorities and key opinion leaders' recognition for this critical COVID-19 therapeutic option. This recognition further validates the importance of our combination therapy for COVID-19 patients and pandemic prevention and control in China," said Rogers Luo,President and General Manager,Greater China of Brii Bio. "We're proud to develop and contribute the first locally-discovered and approved COVID-19 treatment in China. This listing is very timely while China and the rest of the world are on high-alert,evaluating how the Omicron variant is evolving in real-time as we experience the rapid global surge of the Omicron variant. The in vitro pseudovirus testing datafrom independent labs have demonstrated that the amubarvimab/romlusevimab combination retains activity against the Omicron variant. As a combination therapy,the two antibodies offer the unique ability to protect each other against emerging variants and potentially provide a more durable treatment option against COVID variants in the long term to support us in combatting the pandemic."

Brii Bio has made significant efforts to move forward the manufacturing and supply in order to ensure the combination therapy can be made available to patients in need as soon as possible.

On December 8,2021,the National Medical Products Administration (NMPA) of China approved the amubarvimab/romlusevimab combination (previouslyBRII-196/BRII-198 combination) for the treatment in 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.

The NMPA approval of the amubarvimab/romlusevimab combination was based on positive results from the U.S. National Institutes of Health (NIH)-sponsored ACTIV-2 Phase 3 clinical trial with 837 enrolled outpatients. The final results demonstrated 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 in vitro pseudovirus testing data from independent labs demonstrates that the amubarvimab/romlusevimab combination retains activity against the emerging SARS-CoV-2 variant B.1.1.529 (Omicron) and other major variants of concern,including B.1.1.7 (Alpha),B.1.351 (Beta),B.1.617.2 (Delta),AY.4.2 (Delta Plus),B.1.429 (Epsilon),P.1 (Gamma),C.37 (Lambda) and B.1.621 (Mu).

About The Amubarvimab/Romlusevimab Combination (Previously BRII-196 and BRII-198)

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.

In October 2021,the Company initiated and subsequently completed the rolling submission of an emergency use authorization (EUA) application with the U.S. Food and Drug Administration. In addition,the Company is pursuing additional efforts and regulatory filings for the amubarvimab/romlusevimab combination in established and emerging markets with an initial focus on securing access in countries where clinical trials were conducted and where significant gaps in access to highly effective treatments have been identified. The Company is planning further studies in China,to evaluate the use of the amubarvimab/romlusevimab combination among immunocompromised population as an additional measure of prophylaxis.

In response to the emergence of COVID-19 cases in China,including cases caused by the Delta variant,Brii Bio cooperated with governmental agencies and hospitals between June and December 2021 to donate nearly 3,000 doses of the amubarvimab/romlusevimab combination for emergency use in Guangdong,Yunnan,Jiangsu,Hunan,Henan,Fujian,Gansu,Ningxia,Inner Mongolia,Heilongjiang,Qinghai,Guizhou and Liaoning provinces. Nearly 1,000 patients have received the treatment,providing the largest patient experience of amubarvimab/romlusevimab from a single country. Hundreds of healthcare professionals have gained experience and confidence in using this antibody therapy,which has made a significant contribution in the fight against the outbreaks in China.

About COVID-19 Diagnosis and Treatment Guidelines

As a serious acute respiratory infection,COVID-19 is a major public health emergency that threatens global health. The National Health Commission of China's COVID-19 Diagnosis and Treatment Guidelines aims to summarize and update China's clinical experience,continuously improve the standardized diagnosis and treatment,meet the needs of clinical treatment,and increase recovery rates and lower fatality rates.

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.