Promising new data presented this week offers hope for individuals living with hereditary angioedema (HAE), a rare and potentially life-threatening genetic condition. Argo Biopharma, a clinical-stage biotechnology company, announced positive Phase II interim results for its investigational siRNA therapy, BW-20805, which aims to prevent HAE attacks with a long-term effect. The findings, selected as a late-breaking abstract for presentation at the 2026 American Academy of Allergy, Asthma & Immunology (AAAAI) Annual Meeting, demonstrate significant reductions in both HAE attack rates and levels of prekallikrein (PKK), a key target in HAE treatment.
HAE causes unpredictable episodes of swelling in various body parts and in severe cases, can obstruct breathing. Current treatments often require frequent administration, creating a substantial burden for patients. BW-20805 represents a potential shift toward a more convenient, long-lasting prophylactic approach. The therapy utilizes tiny interfering RNA (siRNA) to inhibit the production of PKK, a protein involved in triggering HAE attacks. This targeted approach aims to prevent attacks before they begin, offering a significant improvement over managing symptoms as they arise. The company’s research into RNAi therapeutics is focused on providing better treatment options for patients worldwide.
Significant Attack Reduction Observed in Phase II Trial
The Phase II trial data, titled “Significant HAE Attack Reduction with BW-20805, a Long-Acting Prophylactic Injection-An Ongoing Phase 2 Study in Adults with Hereditary Angioedema,” (POSTER ID: L42) revealed substantial improvements in patients receiving BW-20805. As of the data cut-off, the time-normalized HAE attack rate decreased by 100% in the 600 mg group receiving injections every 24 weeks (Q24W). The 300 mg Q24W group experienced an 89% reduction, while the 300 mg group receiving injections every 12 weeks (Q12W) saw an 87% decrease. Notably, 80% (8 out of 10) of patients treated with BW-20805 remained completely attack-free during the study period.
Beyond attack rate reduction, BW-20805 demonstrated a robust impact on PKK levels. On day 85, the pooled 300 mg groups (Q24W and Q12W) showed a mean reduction in plasma PKK exceeding 92%, while the 600 mg Q24W group achieved approximately a 97% reduction. These reductions were sustained through 169 days of follow-up, with levels remaining at 98% in the 300 mg Q12W group and 97% in the 600 mg Q24W group. These findings suggest the potential for a prophylactic regimen administered every six months (Q6M), which would significantly reduce the treatment burden for patients.
Favorable Safety Profile Supports Further Development
Importantly, BW-20805 was generally well-tolerated throughout the trial. The most common side effects were mild and transient injection-site reactions, and no serious adverse events related to the study drug were reported. This favorable safety profile, combined with the strong efficacy data, positions BW-20805 as a promising candidate for long-term HAE prevention. “The selection of our Phase II interim data as a late breaking abstract at the AAAAI Annual Meeting recognizes the strength and growing body of evidence supporting BW-20805,” said Dr. Dongxu Shu, co-founder and Chief Executive Officer of Argo Biopharma, in a press release. “It highlights its potential to deliver remarkable, sustained reductions in HAE attack rates.”
Understanding Hereditary Angioedema
Hereditary angioedema (HAE) is a rare genetic disorder affecting approximately 1.5 people per 100,000 worldwide [2]. The condition is characterized by unpredictable swelling attacks that can occur in the skin, gastrointestinal tract, and airways. Swelling in the airway can be life-threatening, with a reported mortality rate of up to 40% [1]. Currently available treatments often require frequent infusions or injections, posing logistical challenges and impacting patients’ quality of life. BW-20805’s potential for long-acting prevention addresses a critical unmet need in the HAE community.
- Giavina-Bianchi P, et al. (2011). CLINICS 66(9): 1627–1636.
- Aygören-Pürsün, E, et al. (2018). Orphanet J Rare Dis 13(1): 73.
The full results of the Phase II trial will be presented at the AAAAI Annual Meeting, taking place February 27-March 2, 2026. Researchers will continue to evaluate the optimal dosing regimen for BW-20805, with the goal of providing a best-in-class prophylactic therapy for patients with HAE. Further studies will be crucial to confirm these promising findings and assess the long-term safety and efficacy of this novel treatment approach.
Disclaimer: The information provided in this article is for general knowledge and informational purposes only, and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
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