Brii Bio Announces Amubarvimab/Romlusevimab Combination Received Approval from NMPA as First COVID-19 Neutralizing Antibody Combination Therapy in China

The approval marks the first locally-discovered and approved SARS-CoV-2 target-specific treatment in China,through a randomized,double-blind and placebo-controlled trial

Brii Bio is also seeking U.S. FDA Emergency Use Authorization for the amubarvimab/romlusevimab combination

DURHAM,N.C. and BEIJING,Dec. 9,2021 --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 Medical Products Administration (NMPA) of China has granted approval of the company's monoclonal neutralizing antibody (mAb) therapy,the amubarvimab/romlusevimab combination (previously BRII-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.

"We are excited to achieve this important milestone. This accomplishment is a testament to our steadfast commitment to accelerating innovation in infectious diseases,and our ability to fulfill global unmet needs with speed,scientific rigor and impressive results," said Rogers Luo,President and General Manager,Greater China of Brii Bio. "As a startup multi-national biotech company co-located in both China and the U.S.,we are working to advance access to this treatment for a broad range of COVID-19 patients in China,while also scaling its effort to match the need for COVID-19 treatment options to combat the pandemic."

The NMPA approval is based on positive final and interim results from the NIH-sponsored ACTIV-2 Phase 3 clinical trial with 847 enrolled outpatients. The final results demonstrated a statistically significant 80% (78% in interim results) 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.

In less than 20 months,Brii Bio progressed the amubarvimab/romlusevimab combination from discovery to completion of Phase 3 development leading to this rapid approval by the NMPA. This approval represents the highly successful partnership with the best scientists and clinical investigators in China and around the globe on a shared mission,including the3rd People's Hospital of Shenzhen and Tsinghua University,who discovered these neutralizing antibody leads; the U.S. National Institute of Health (NIH),the AIDS Clinical Trial Group (ACTG),who sponsored and led the ACTIV-2 trial.

"As the first COVID-19 treatment in China,the amubarvimab/romlusevimab combination demonstrates positive clinical outcomes and favorable safety in global,multicenter trials. It is the only monoclonal antibody combination globally with confirmed clinical efficacy among patients infected by SARS-COV-2 variants in the pivotal pre-marketing trial," said Prof. Linqi Zhang,Director of the Global Health and Infectious Diseases Research Center and Comprehensive AIDS Research Center at School of Medicine Tsinghua University. "The antibody combination provided world-class treatment for China to fight against the COVID-19 epidemic,which fully demonstrates our rich experience,scientific-technological reserves,and our accountability and ability in fighting against infectious diseases and making an important contribution in the prevention and control of the epidemic in China and the world. We are pleased to partner with the 3rd People's Hospital of Shenzhen and Brii Bio in the discovery,clinical research,and translational research of the combination therapy and ultimately achieved this outstanding milestone. We will continue to evaluate the use of the amubarvimab/romlusevimab combination among immunocompromised population as an additional measure of prophylaxis."

"Since the very beginning of the COVID-19 pandemic,our guiding principle has been a science-based approach as we continue to fight against the pandemic. Our research team successfully derived two highly active neutralizing antibodies from convalesced COVID-19 patients,which laid the solid foundation for developing the amubarvimab/romlusevimab combination against COVID-19," said Lei Liu,Director of the National Clinical Research Center for Infectious Diseases in Shenzhen and Party Secretary of the 3rd People's Hospital of Shenzhen. "We're very pleased to partner with Prof. Linqi Zhang from Tsinghua University and Brii Bio to contribute our expertise and we're proud to contribute China's first COVID-19 treatment during a time where the pandemic continues to evolve."

About the amubarvimab/romlusevimab (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 has cooperated with governmental agencies and hospitals since June 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 900 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 ACTIV-2 Phase 3 Study

The NMPA's approval of the amubarvimab/romlusevimab combination is primarily based on the final and interim results from Phase 3 of the NIH-sponsored ACTIV-2 trial (NCT04518410). The final results demonstrated a statistically significant reduction,80%,of relative risk in the combined endpoint of hospitalization and death,with fewer deaths through 28 days on the treatment arm (0) relative to placebo (9),in non-hospitalized COVID-19 patients at high risk of clinical progression. No new safety concerns were identified.

The interim results announced on October 4,2021demonstrated that the combination therapy achieved a statistically significant reduction,78%,of relative risk in the combined endpoint of hospitalization and death in non-hospitalized COVID-19 patients at high risk of clinical progression (nominal one-sided p value = 0.00001). Of those subjects who received treatment with amubarvimab/romlusevimab combination within five days of symptom onset,2% (4/196) progressed to hospitalization or death,compared with 11% (21/197) in the placebo arm. Similarly,2% (5/222) of subjects who received treatment with theamubarvimab/romlusevimab combination at six to 10 days following symptom onset progressed to hospitalization or death,compared with 11% (24/222) of those receiving placebo. This analysis also showed zero deaths in the treatment arm versus eight deaths in the placebo arm through 28 days. Grade 3 or higher adverse events (AEs) were less common in the amubarvimab/romlusevimab combination treatment arm versus placebo,3.8% (16/418) versus 13.4% (56/419),with no drug related severe adverse events (SAEs) or infusion-related reactions observed.

This study was conducted at clinical trial sites around the world,including the U.S.,Brazil,South Africa,Mexico,Argentina and the Philippines,with patients enrolled between January and July of 2021 – a period of rapid global emergence of novel SARS-CoV-2 variants. Data on the clinical efficacy of the amubarvimab/romlusevimab combination by variant type will also be evaluated as part of the study. Current in vitro pseudovirus testing data suggests 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) and B.1.621 (Mu). Testing against the B.1.1.529 (Omicron) variant is currently ongoing.

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.