SHANGHAI and BOSTON, Nov. 6, 2025 /PRNewswire/ -- Argo Biopharmaceutical Co., Ltd. (Argo Biopharma), a clinical-stage small interfering RNA (siRNA) therapeutics company, today announced it will present Phase I data for BW-20805 at the American College of Allergy, Asthma & Immunology (ACAAI) 2025 Annual Scientific Meeting, taking place November 6–10 in Orlando, Florida, USA.

BW-20805 is an investigational siRNA therapy that targets and inhibits prekallikrein (PKK), a well-validated target for hereditary angioedema (HAE) treatment, offering the possibility of prevention of HAE attacks with a significant, long-term effect.

The poster presentation (POSTER ID: R094), titled "Hereditary Angioedema Prophylaxis With Prekallikrein siRNA-Phase 1 Safety Outcomes And Prekallikrein Levels," will be presented throughout the ACAAI meeting. These data highlight that BW-20805 was well tolerated and demonstrated a favorable safety profile and achieved rapid, profound, and sustained reductions in plasma PKK levels.

Key findings:

• BW-20805 was generally well tolerated across all dose levels (50–600 mg), with no dose-dependent increase in treatment-emergent adverse events (TEAEs).
• No deaths, serious adverse events (SAEs) related to study drug, or discontinuations due to TEAEs were reported.
• Treatment with BW-20805 led to rapid, profound, and durable reductions in plasma PKK levels, achieving mean maximum reductions of approximately 75% (50 mg), 87% (150 mg), 94% (300 mg), and 95% (600 mg).
• PKK suppression was sustained for up to 24 weeks, supporting the potential for 6-month dosing intervals.
• Other pharmacodynamic biomarkers, including plasma proenzyme activation and cleaved high-molecular-weight kininogen (cHMWK), also showed significant reductions, reinforcing the drug's biological activity.

"We are pleased with the results shared at ACAAI, showing that BW-20805 was well tolerated across all dose levels, with rapid, profound, and durable reductions in plasma PKK levels achieved," said Dr. Dongxu Shu, co-founder and Chief Executive Officer of Argo Biopharma. "We look forward to further advancing BW-20805 as a potential long-acting and effective therapy for people living with HAE."

About Hereditary Angioedema (HAE)

Hereditary angioedema (HAE) is a rare genetic condition that causes sudden and unpredictable swelling in different parts of the body. In severe cases, it can affect the throat and become life-threatening, with a mortality rate of up to 40%.¹ HAE affects about 1.5 people per 100,000 worldwide.² Current treatments require frequent dosing, highlighting the need for long-acting, preventive therapies. BW-20805 targets human hepatic PKK mRNA to inhibit PKK gene expression, offering the potential for effective prevention of HAE attacks with a significant and longer-lasting therapeutic effect.

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 molecule 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.

References：

1. Pedro Giavina-Bianchi, et al. CLINICS (2011); 66(9):1627-1636
2. Aygören-Pürsün, E., et al. (2018). Orphanet J Rare Dis 13(1): 73.

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SOURCE Argo Biopharmaceutical Co., Ltd