Brii Bio Announces Amubarvimab/Romlusevimab Combination Retains Neutralizing Activity Against Omicron SARS-CoV-2 Variant

DURHAM,N.C. and BEIJING,Dec. 12,2021 --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 new in vitro pseudoviris neutralization data demonstrating that its amubarvimab/romlusevimab combination therapy (previouslyreferred to as combination BRII-196/BRII-198) retains activity against the new Omicron SARS-CoV-2 variant (B.1.1.529).

These data add to the growing body of evidence demonstrating that the amubarvimab/romlusevimab combination retains activity against key World Health Organization's COVID-19 variants of concern,also including Delta (B.1.617.2) and Delta Plus (AY.4.2).

"We believe the amubarvimab/romlusevimabcombination has the potential to be a best-in-class treatment option for a broad range of high risk COVID-19 patients. These latest findings underscore that our combination antibody therapy holds up well against the Omicron variant that pose a significant public health threat worldwide," said Zhi Hong,Ph.D.,Chairman and Chief Executive Officer of Brii Bio. "As experts around the world continue to track Omicron and other variants of concern,independent labs have demonstrated that our combination therapy will continue to provide clinical benefits for both patients who present early for treatment and those who present late for treatment. We look forward to continuing our work with the U.S. FDA and regulatory authorities around the world to bring our combination therapy to patients in need as quickly as possible."

The in vitro tests against pseudovirus from independent labs have demonstrated the Omicron variant remains susceptible to neutralization by the amubarvimab/romlusevimab combination. While there wassubstantial drop in activity for amubarvimab against the Omicron variant,romlusevimab was not impacted by the omicron variant. Together,the combination therapy retains neutralizing activity against the Omicron variant,validating the importance of a combination mAb strategy to ensure clinical benefits forpatients at high risk for clinical progression. Specific data will be presented in scientific publications in the near future.

"These new preclinical data provide further evidence of that the amubarvimab/romlusevimab combination provides significant benefits for high risk patients who contract the Omicron variant,given its highly successful track record thus far to reduce hospitalization and death among all tested variants of concern,including the Delta variant," said David Margolis,M.D.,MPH,Vice President and Head of Infectious Diseases Therapy at Brii Bio. "As a combination therapy,amubarvimab/romlusevimab offer the unique ability to protect each other against the emerging variants and potentially provide a more durable treatment option against COVID variants in the long term as we continue fighting to save lives and reduce the severe health consequences of this pandemic."

The FDA is currently reviewing Brii Bio's EUA application for the amubarvimab/romlusevimab combination. The application is based on data that show the amubarvimab/romlusevimab combination demonstrated a statistically significant 80% reduction of hospitalization and death and improved safety over placebo in non-hospitalized COVID-19 patients at high risk of clinical progression to severe disease. The proportion of deaths from any cause was observed to be significantly less (p=0.0037) on the amubarvimab/romlusevimab combination treatment (n=0) compared to placebo (n=9) from study Day 0 through Day 28. Similar efficacy rates were observed in participants initiating therapy early (0-5 days) and late (6-10 days),following symptom onset,providing critically needed therapeutic option to patients with challenges in timely access to care who may present later.

Conference Call

Brii Bio management will host a conference call on Monday,13 December,2021 at 8:30 a.m. Hong Kong time to discuss the details. To access the live conference call,please visit the Investor Relations section of the company's website at https://hkexir.briibio.com/ir/Presentation.php.

About 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 December 2021,the amubarvimab/romlusevimab combination was approved by the National Medical Products Administration (NMPA) of China for the treatment 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.

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.

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.