SHANGHAI, CHINA and BOSTON, USA – September 8, 2025—Argo Biopharmaceutical Co., Ltd. (Argo Biopharma), a clinical-stage small interfering RNA (siRNA) therapeutics company, today announced that the first patient dosing has been completed for the Phase II clinical trial of its innovative siRNA-based therapy in chronic hepatitis B (CHB) patients. The Phase II study will test both BW-20507 mono-therapy and combination therapy of BW-20507 and PEG-IFNα. Prior to that, in June 2025, Argo Biopharma received the Investigational New Drug (IND) approval from the National Medical Products Administration of China (NMPA). BW-20507 was granted Breakthrough Therapy Designation (BTD) from NMPA in June 2025, and its best-in-class Phase I/IIa clinical data were presented as a late-breaking poster at the EASL Congress (European Association for the Study of the Liver Congress) in May 2025.

Preclinical and early clinical data have demonstrated significant reduction of hepatitis B surface antigen (HBsAg) and HBV DNA levels. These findings highlight the potential of BW-20507 to achieve strong antiviral activity and meaningful immune restoration, supporting its promise as a best-in-class candidate for the functional cure of chronic hepatitis B.

“With the initiation of our Phase II trial, we are moving closer to delivering a transformative therapy for patients living with chronic hepatitis B. ” said Dr. Dongxu Shu, Co-founder and CEO of Argo Biopharma，“Building on the BTD from the NMPA and the encouraging Phase I/IIa data presented at EASL 2025, we remain committed to advancing BW-20507 efficiently and safely, with the goal of bringing a best-in-class treatment to patients who need it most.”

About Chronic Hepatitis B (CHB)

Chronic HBV affects approximately 296 million individuals globally, resulting in an estimated 820,000 deaths each year due to complications including cirrhosis, liver decompensation, and hepatocellular carcinoma (HCC). Currently, there remains a significant unmet medical need for functional cure treatments for CHB.

siRNA therapies, which target viral mRNA, represent a promising pathway to a functional cure.

About Argo Biopharma

Argo Biopharma is a clinical-stage biotechnology company committed to developing next-generation RNAi therapeutics to provide better treatment options for patients worldwide. The company has established a robust and diverse pipeline of RNAi drug candidates targeting a wide range of indications, including cardiovascular diseases, viral infections, metabolic conditions, and specialty/rare diseases. Currently, Argo Biopharma has six RNAi candidates in clinical development.

For more information, visit www.argobiopharma.com .