Ulefnersen Trial Success Offers New Hope for Rare FUS-ALS

A rare form of ALS, often striking young people, may finally have an effective treatment. The investigational antisense therapy ulefnersen met its primary endpoint in the Phase 3 FUSION trial, marking the first time a placebo-controlled study has successfully targeted the genetic cause of FUS-ALS to alter disease progression.

Corp and Tech·September 22, 2026·reads: 713

Ulefnersen Trial Success Offers New Hope for Rare FUS-ALS

Developers Otsuka and Ionis reported that the drug significantly improved a combined measure of patient function and survival. Beyond the primary data, the therapy demonstrated a favorable safety profile and positive secondary measures. This breakthrough follows two decades of research into antisense technology, an area the ALS Association began backing long before it became a standard approach for neurodegenerative conditions.

The clinical milestone is deeply tied to the advocacy of Jaci Hermstad, a young woman who lived with FUS-ALS and pushed for research funding when resources were scarce. Her efforts, alongside partnerships between the ALS Association and Project ALS, sustained the early clinical work at Columbia University. Those foundational steps, which included an expanded access program led by Dr. Neil Shneider, provided the necessary evidence to launch the global FUSION trial. While Hermstad passed away in 2020, her legacy remains the driving force behind this development.

Ulefnersen awaits regulatory approval, and the ALS Association is now calling on Otsuka, Ionis, and the FDA to expedite the review process. The organization is pushing for priority status to ensure that patients gain access to the therapy as quickly as possible. For families facing a diagnosis that has historically lacked any targeted treatment, these results offer a rare, tangible path forward.