Alnylam Says Phase 1b Brezosiran Study Showed Dose-Dependent CSF Mutant Huntingtin Reductions, Up To 83% Individually, No Dose-Dependent Safety Signals; Pivotal Study Planned 2027 Pending Regulatory Alignment

- Initial Phase 1b results show mean reduction of cerebrospinal fluid mutant huntingtin of 60 to 64% at month 3 with individual reduction of up to 83% and encouraging safety and tolerability with potential for twice yearly dosing -

- Unique targeting approach reduces both mutant huntingtin and shorter mutant HTT1a-

- Placebo-controlled pivotal study planned for 2027, pending regulatory alignment -

- Alnylam to discuss Huntington’s disease program at October 26 RNAi Roundtable -