Alnylam to launch pivotal Huntington’s trial after early study shows strong huntingtin knockdown

Alnylam Pharmaceuticals announced plans to move its Huntington’s disease RNAi therapy brezosiran into a pivotal, placebo‑controlled trial slated for 2027, pending regulatory alignment.

The decision follows a Phase 1b study where the drug, previously known as ALN‑HTT02, produced dose‑dependent reductions of mutant huntingtin protein in cerebrospinal fluid, with the highest dose achieving a mean knockdown of about 60‑64% after three months.

The results were presented in a poster at the European Huntington’s Disease Network Clinical Research Congress in Krakow and were confirmed by two independent assays, according to the company’s press release.

Alnylam’s partnership with Regeneron, established in 2019 and valued at over $1 billion, underpins the development program, and analysts note that a successful approval could represent a multibillion‑dollar market opportunity given the lack of existing treatments for Huntington’s disease.