Brii Biosciences Announces Top-line Results from Phase 1 Study of BRII-296, A Long-Acting Therapy in Development for Postpartum Depression

Data demonstrated that a single administration of BRII-296 at 600 mg delivered a favorable pharmacokinetic profile and is safe and well-tolerated in healthy subjects

Findings suggest BRII-296 has potential to provide a safe and effective,one-time injectable treatment option to people with PPD in an outpatient setting

Company has identified an optimal dose regimen for BRII-296 for the upcoming Phase 2 study expected to commence by end of 2022

DURHAM,N.C. and BEIJING,Sept. 26,2022 --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 top-line results from a Phase 1 study evaluating its long-acting,single-injection therapy,BRII-296,in development for the treatment of postpartum depression (PPD). These data show that a single treatment via intramuscular (IM) injection of 600 mg of BRII-296 achieved dose linearity,early drug absorption,gradual and extended release profiles without the need for dose titration or tapering,providing confidence that this dose has potential to achieve clinical efficacy in the treatment of PPD. The selected dose regimen will be evaluated in a Phase 2 clinical trial that is expected to begin this year.

BRII-296 acts as a novel gamma-aminobutyric acid A (GABAa) receptor positive allosteric modulator (PAM) with a unique long-acting formulation that does not require cessation of breastfeeding and enables the drug to be effective for weeks after the patient leaves the injection appointment. It is designed to provide a rapid,profound and sustained reduction in depressive symptoms of PPD and may offer substantial clinically meaningful advantages over currently available treatment options for PPD.

"We are encouraged by the possibility of providing a novel treatment option to the 900,000 people in the U.S. affected by postpartum depression each year in which the current standard of care is suboptimal,often requiring hospitalization,repeat therapy and daily doses of treatment," said Ji Ma,Ph.D.,Vice President of Preclinical Development and Clinical Pharmacology at Brii Bio,and lead author. "These data reinforce the potential for BRII-296 to redefine the PPD treatment landscape by providing a one-time,outpatient therapy that may effectively treat a range of depressive symptoms while maintaining a favorable safety and tolerability profile,including minimal exposure to breastfed infants."

"Initial results from this study are an important step forward as we continue to advance the development of BRII-296 in a robust and thoughtfully designed Phase 2 clinical study later this year that will incorporate fundamental patient experiences and preferences," said Aleksandar Skuban,M.D.,CNS Diseases Therapy Area Head of Brii Bio. "This comprehensive approach to development is critical in areas such as PPD where there are often considerable barriers to accessing care,in part because of wide-reaching social stigmas and a lack of disease awareness. This program reinforces Brii's dedication to operating at the intersection of scientific innovation and patient insights in order to inform the full spectrum of strategic development in mental health conditions such as PPD as well as our broader global public health-inspired pipeline."

Data from healthy subjects in cohorts 1-15 were presented in a poster,titled Safety,Tolerability,and Pharmacokinetics of BRII-296,An Extended-Release Injectable Aqueous Suspension Formulation of Brexanolone in Healthy Adult Subjects,at the International Marcé Society Conference taking place in London,United Kingdom September 19-23,2022. The full Phase 1 dataset will be presented at a scientific meeting later this year.

About BRII-296 Phase 1 Trial

The completed open-label,Phase 1,single ascending dose study assessed the safety,tolerability and PK of BRII-296 as a single-injection treatment option for PPD in 116 subjects enrolled across 16 cohorts. Three formulation concentrations (100 mg/mL,200 mg/mL and 300 mg/mL) were administered via one or more IM injections to healthy adults at total dose levels of 30 mg,75 mg,100 mg,200 mg,300 mg and 600 mg. In addition,oral prophylactic treatment,or local steroid administration with BRII-296 (Depo Medrol via co-injection or admix) were evaluated to manage local injection site reactions (ISRs).The local steroid administration was shown in the study to effectively manage injection site reactions (ISRs).

Of the 116 subjects,98 subjects reported treatment emergent adverse events (TEAEs),with the majority considered drug-related and attributed to ISRs. Most ISRs were mild to moderate in severity and none lead to premature discontinuation from the study. There were no life threatening TEAEs,TEAEs leading to premature discontinuation of study,SAEs,or deaths.

About Postpartum Depression

Postpartum depression (PPD) is the most common psychological condition impacting people after giving birth. Affecting approximately 900,000 birthing people in the U.S. each year,including those who have miscarried or have had a stillbirth,PPD can present significant physical and mental health risks to the mother. In fact,suicide and overdose are the leading causes of death for childbearing people in the first year following pregnancy. Some healthcare providers believe the prevalence of PPD could be at least double,given unreported and untreated cases. PPD can also have negative effects on the maternal-infant relationship and it may lead to longer-term child development problems. Despite the prevalence and societal impact of PPD,currently approved treatment options remain limited and are associated with significant disruptions to daily life,including required hospitalization,repeat therapy and daily doses of treatment.

About BRII-296

BRII-296 is a novel,single injection therapeutic candidate in development for the treatment and prevention of postpartum depression (PPD). It acts as a gamma-aminobutyric acid A (GABAa) receptor positive allosteric modulator (PAM) and is designed to provide a rapid,profound and sustained reduction in depressive symptoms of PPD with the potential to lead to greater adherence,convenience and fewer side effects compared to the current standard of care. BRII-296 will continue to be evaluated in an upcoming Phase 2 study for the treatment of PPD and is also in development for the prevention PPD.

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.