Alnylam's Brezosiran Lowers Mutant Huntingtin 60-64% in Highest-Dose Group in Phase 1b Trial

• Alnylam Pharmaceuticals reported positive initial Phase 1b results for brezosiran, an investigational Huntington's disease treatment.
• The highest dose produced mean cerebrospinal fluid mutant huntingtin reductions of 60-64% at three months; the maximum individual reduction was 83%.
• Follow-up of up to 12 months showed no dose-dependent increases in cerebrospinal fluid inflammatory markers, neurofilament light chain or brain ventricular volume.
• Durability of huntingtin lowering supports potential twice-yearly dosing; an open-label extension will evaluate treatment every six months for up to 36 months.
• A placebo-controlled pivotal study is planned for 2027, pending regulatory alignment, to evaluate whether brezosiran slows disease progression in adults.

Disclaimer: This news brief was created by Public Technologies (PUBT) using generative artificial intelligence. While PUBT strives to provide accurate and timely information, this AI-generated content is for informational purposes only and should not be interpreted as financial, investment, or legal advice. Alnylam Pharmaceuticals Inc. published the original content used to generate this news brief via Business Wire (Ref. ID: 20261023812467) on October 23, 2026, and is solely responsible for the information contained therein.