Alnylam Pharmaceuticals, Inc.: Alnylam Announces Positive Initial Phase 1b Data for Brezosiran (ALN-HTT02) Demonstrating Deep and Durable Huntingtin Lowering in Huntington's Disease

Alnylam Pharmaceuticals reported positive initial Phase 1b trial results for ALN-HTT02, an investigational RNAi therapeutic for Huntington's disease. The treatment, also known as brezosiran, showed dose-dependent reductions of mutant huntingtin protein in cerebrospinal fluid. Alnylam plans a placebo-controlled study in 2027, pending regulatory alignment. Shares closed at $227.28 on NasdaqGS.

Alnylam Pharmaceuticals reported positive initial Phase 1b trial results for brezosiran, an investigational treatment for Huntington's disease. The study showed dose-dependent reductions of mutant huntingtin protein in cerebrospinal fluid, with a mean reduction of 60-64% at the highest dose. The company plans to initiate a pivotal study in 2027, pending regulatory alignment. Brezosiran is being developed in collaboration with Regeneron Pharmaceuticals.

Alnylam Pharmaceuticals (ALNY) reported Phase 1b data for brezosiran, showing 60–64% CSF mHTT reductions at the highest dose, with a maximum individual reduction of 83%. The company plans a placebo-controlled pivotal study in 2027, pending alignment. The data represents early clinical validation of Alnylam’s CNS RNAi approach in Huntington’s disease.

Alnylam's experimental Huntington’s drug, brezosiran, showed a 60% mean reduction in mutant huntingtin protein in a Phase 1b trial, with up to 83% reduction in one participant. The company plans a pivotal study in 2027, pending regulatory alignment. Brezosiran targets all forms of huntingtin protein, including mutant HTT1a. Alnylam will discuss the program at an upcoming RNAi Roundtable.

The Scottish Medicines Consortium approved vutrisiran for adults with ATTR-CM, enabling access via NHS Scotland. Developed by Alnylam, vutrisiran is a long-acting treatment targeting the underlying biology of the condition. Around 1,800 people in Scotland may be affected. The therapy is also indicated for hereditary ATTR amyloidosis. The decision follows a similar recommendation by NICE in England and Wales.

Alnylam Pharmaceuticals (ALNY) stock rose 8.51% on positive RNAi pipeline updates and analyst upgrades. Analysts set price targets ranging from $318 to $455, citing strong clinical data and growth prospects. The company reported $3.71B in trailing revenue, a 92.1% gross margin, and positive EBIT margin of 23.4%.