Argo Biopharma to Present Positive Phase II Updated Results of siRNA Therapeutic BW-20805 for HAE at Bradykinin Symposium 2026

- Oral Presentation in Session VI: Hereditary Angioedema

SHANGHAI and NEW YORK, Sept. 4, 2026 /PRNewswire/ -- Argo Biopharmaceutical Co., Ltd. (Argo Biopharma), a clinical-stage small interfering RNA (siRNA) therapeutics company, today announced that updated Phase II data from its ongoing BW-20805 study for hereditary angioedema (HAE) was selected for oral presentation at the Bradykinin Symposium 2026, being held on September 3-4, 2026 in Berlin, Germany. BW-20805 has shown impressive efficacy throughout the Phase II trial and data presented at the Bradykinin Symposium continues to support its differentiated clinical profile with high potency and less frequent dosing.

BW-20805 is an investigational siRNA therapeutic designed to silence plasma prekallikrein (PKK) messenger RNA, targeting a clinically validated pathway in HAE. By reducing PKK production, BW-20805 is being evaluated for its potential to provide durable prevention of HAE attacks with infrequent dosing.

"The updated Phase II results being presented at the Bradykinin Symposium 2026 provide continued clinical evidence for BW-20805's differentiated potential in HAE prophylaxis," said Dr. Dongxu Shu, co-founder and Chief Executive Officer of Argo Biopharma. "The magnitude and durability of attack-rate reduction observed through Day 169, together with sustained PKK suppression and a well-tolerated safety profile, support continued advancement of this program as we work to address the need for effective therapies with less frequent dosing."

The presentation, titled "Significant Durable HAE Attack Reduction with BW-20805 — Phase 2 Update," includes data from an open-label, global, multicenter Phase II study evaluating three long-interval dosing regimens of BW-20805 in adults with HAE type 1 or 2. As of the June 2026 data cut-off, 25 participants were randomized and dosed across three treatment groups: BW-20805: 600 mg every 24 weeks (Q24W), 300 mg Q24W, and 300 mg every 12 weeks (Q12W). The study evaluated the change from baseline in time-normalized monthly (per 4 weeks) HAE attack rate over Days 29 to 169 as the primary endpoint, with safety, pharmacokinetics and pharmacodynamics assessed as secondary endpoints.

Key Data Highlights:

• BW-20805 demonstrated substantial reductions in monthly HAE attack rates across all treatment groups in the primary endpoint analysis population (n=24). Mean time-normalized monthly attack rates decreased by 83% in the 600 mg Q24W group, 96% in the 300 mg Q24W group, and 93% in the 300 mg Q12W group
• Attack-free rates over Day 29 to 169 were 50% (4/8), 75% (6/8), and 62.5% (5/8) in the 600 mg Q24W, 300 mg Q24W, and 300 mg Q12W groups, respectively. Across all three regimens, attacks became markedly less frequent and milder after dosing.
• BW-20805 achieved rapid and sustained pharmacodynamic activity. In the PKK-evaluable population (n=19), mean plasma PKK reductions at Day 169 were 86%, 85%, and 94% in the 600 mg Q24W, 300 mg Q24W, and 300 mg Q12W groups, respectively.
• BW-20805 was generally well tolerated across all regimens in the safety analysis set (n=25). Treatment-emergent adverse events were predominantly mild; transient injection-site reactions were the most common adverse events of special interest. No treatment-emergent adverse event led to treatment discontinuation, withdrawal, or death, and no participant met protocol-defined hepatic laboratory criteria.

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 eight RNAi candidates in clinical development.

For more information, please visit www.argobiopharma.com.

References：

1. Pedro Giavina-Bianchi P, et al. (2011). CLINICS 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