D1.363 - Long-Acting Prophylactic Injection BW-20805: Remarkable and Sustained HAE Attack Reduction — Updated Analysis from an Ongoing Phase 2 Study

Plasma prekallikrein (PKK) is a validated target for hereditary angioedema (HAE) therapy. BW-20805, a chemically modified, GalNAc-conjugated siRNA which can suppress hepatic PKK expression, offering a long-acting preventive approach for HAE attacks

This open-label, international, multicenter study evaluated BW-20805 in 24 adults with HAE types I/II across three regimens (600 mg Q24W, 300 mg Q24W, 300 mg Q12W, n=8/Group). Changes in time-normalized HAE attack rate from baseline were analyzed from Day 29 after the first dose. The statistics are up to Dec 2025. 

As for the cut-off, 18 participants were randomized and dosed (16 with post-dose data beyond Day 29). Time-normalized HAE attack rates were reduced by 99% in 600 mg Q24W with 83% (5/6) attack-free, 93% in 300 mg Q24W with 60% (3/5) attack-free, and 95% in 300 mg Q12W with 60% (3/5) attack-free. Plasma PKK declined rapidly, with mean reductions exceeding 94% in pooled 300 mg groups and 96% in 600 mg Q24W on Day 85. Among participants completing 169 days, mean PKK reductions exceeded 90% across all three groups, with sustained robust suppression following repeat dosing. BW-20805 was well tolerated, with mainly mild, transient injection-site reactions resolved within 1 day and no treatment-related serious adverse events occurred. 

This open-label analysis—now including more treated participants with extended follow-up—demonstrates marked and sustained HAE attacks reductions with BW-20805 and a consistent safety profile across repeat doses. Robust and sustained PKK suppression supports further evaluation of a Q6M dosing regimen. The Phase 2 study is ongoing with additional data forthcoming.