SHANGHAI, CHINA and BOSTON, MA,USA—May 7, 2025—Argo Biopharmaceutical Co., Ltd. (Argo Biopharma), a clinical-stage biotechnology company leveraging a next-generation siRNA technology through its proprietary RADS platform, today announced it will present Phase 1/2a clinical data at the European Association for the Study of the Liver Congress (EASL Congress), taking place May 7-10, 2025 in Amsterdam, the Netherlands.

The poster presentation (POSTER ID:LBP-008) titled “Safety, Tolerability, and Remarkable Hepatitis B Surface Antigen Reduction in Chronic Hepatitis B Patients Treated With BW-20507”, will be displayed in the late-breaker area throughout the Congress. It highlights topline findings from an ongoing Phase 1/2a study of BW-20507 monotherapy in virologically suppressed and NUC-naïve participants with chronic hepatitis B (CHB), conducted in Hong Kong (China) and Thailand.

BW-20507 is an siRNA molecule specifically targeting the S region of HBV messenger RNA, developed in-house by Argo Biopharma for the treatment of CHB using proprietary siRNA platform technology and unique know-how. “Argo’s team of dedicated scientists and clinicians has developed a molecule showing significant efficacy in early-stage clinical trials and great promise for addressing HBV patients’ unmet medical needs.” said Dongxu Shu, Ph.D., Co-Founder, Chairman of the Board, and Chief Executive Officer. “This marks the fourth molecule from Argo to demonstrate clinically differentiated efficacy, dosing, and safety for patients. These results represent a significant milestone in advancing BW-20507 and mark a step forward toward better outcomes for CHB patients.”

Key Findings to Be Presented at EASL:

    1. BW-20507 administered subcutaneously every four weeks for a total of three doses demonstrated significant, dose-dependent reductions in HBsAg, with maximum declines of -2.9 to -3.2 log₁₀ IU/mL observed in the 200 mg and 400 mg cohorts.

    2. Among participants with baseline HBsAg <1,000 IU/mL, 56% (5 out of 9) achieved HBsAg loss during the study.

    3. Potent HBV DNA suppression was also observed in NUC-naïve participants who did not receive NUC therapy during the study.

    4. These promising antiviral results, combined with the favorable safety and tolerability profile, support the continued clinical development of BW-20507.

“These data represent a meaningful advancement toward a functional cure for chronic hepatitis B,” said Professor Man-Fung Yuen of Queen Mary Hospital, The University of Hong Kong, leading principal investigator of the study and presenting author at EASL 2025. “We are particularly encouraged by the remarkable HBsAg reduction observed after just three doses of BW-20507 — with some participants even achieving HBsAg loss, a result rarely seen with other siRNA monotherapies. These findings offer new hope of achieving a functional cure for patients living with CHB.”

Based on these promising results, Argo Biopharma plans to advance BW-20507 into Phase 2b clinical development in 2025. A monotherapy Phase 2b study is expected to initiate in Q2 2025, followed by a combination Phase 2 study planned for Q3 2025. These studies aim to further evaluate the potential of BW-20507 to deliver functional cure solutions for CHB.

About Chronic Hepatitis B (CHB)

Chronic HBV infection is one of the leading causes of liver disease, affecting approximately 296 million people worldwide and causing 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.

About Argo Biopharma

Argo Biopharma is a clinical-stage biotechnology company committed to developing a new generation of RNAi drugs to provide better treatment options for patients worldwide. Argo Biopharma’s hepatic and extrahepatic platforms support a robust and diversified pipeline of RNAi drug candidates in cardiometabolic diseases, specialty diseases, viral infections, CNS and rare diseases. Currently, Argo Biopharma has six RNAi drug candidates in the clinical stage.

In a noteworthy milestone, Argo Biopharma entered into a strategic partnership with Novartis in January 2024 for $185 million in upfront payments and a total value exceeding $4 billion.

For more information, visit www.argobiopharma.com .