ALS Association Statement on Positive Phase 3 Results for Ulefnersen in FUS-ALS

ARLINGTON, Va., Sept. 22, 2026 /PRNewswire/ -- The ALS Association celebrates today's news that ulefnersen, an investigational antisense therapy for people with FUS-ALS, met its primary endpoint in the Phase 3 FUSION trial. Ulefnersen is now the second antisense therapy, after Qalsody (tofersen) for SOD1-ALS, to show it can change the course of a genetic form of ALS, raising hope that this approach can be used to treat more types of the disease. The ALS Association was an early funder of antisense research in ALS, taking a chance on the technology two decades ago, before it had ever been tried in neurodegenerative disease.

The drug's developers, Otsuka and Ionis, reported that ulefnersen significantly improved a combined measure of function and survival compared to placebo, with supporting results on key secondary measures and a favorable safety profile.

This is the first placebo-controlled trial to show that targeting the genetic cause of FUS-ALS can change the course of the disease. FUS-ALS is rare, but it is the most common cause of juvenile ALS, and it often progresses quickly in young people. Until now, these families have had no treatment designed for them.

"Today's results happened because of an amazing young woman named Jaci Hermstad, her family and a community that refused to accept that a rare form of ALS was too rare to treat," said Calaneet Balas, president and CEO of the ALS Association. "We are fighting for families affected by this especially cruel type of ALS and we hope today's news provides encouragement. We are proud that ALS Association donors helped make the early work possible, and we will keep pushing for a fast, thorough regulatory review."

Jaci Hermstad was a young woman living with FUS-ALS whose advocacy helped launch the research, and for whom the drug was first named jacifusen. When the early clinical work at Columbia University ran short of resources, the ALS Association partnered with Project ALS to fund it, and later supported the expanded access program led by Columbia's Dr. Neil Shneider that treated additional people with FUS-ALS. Those early results, including one participant who regained the ability to walk and breathe on her own, helped pave the way for the global Phase 3 trial.

Today, we are thinking of Jaci, who died in 2020, and of her family. Her courage in facing this disease, and her determination to help others who would come after her, made this day possible.

Ulefnersen is not yet approved. The ALS Association urges Otsuka, Ionis, and the FDA to move with the urgency these results demand, including priority review and broad access for people living with FUS-ALS while the therapy is under review. We will continue to advocate for timely access and will share updates with the community as they become available.

About the ALS Association
The ALS Association is the largest philanthropic funder of ALS research in the world. The Association funds global research collaborations, assists people with ALS and their families through its nationwide network of care and certified clinical care centers, and advocates for better public policies for people with ALS. The ALS Association is working to make ALS a livable disease while urgently searching for new treatments and a cure. For more information about the ALS Association, visit our website at als.org.

About ALS
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord. Over the course of the disease, people lose the ability to move, to speak, and eventually, to breathe. The disease is always fatal, usually within five years of diagnosis. Few treatment options exist, resulting in a high unmet need for new therapies to address functional deficits and disease progression.

SOURCE The ALS Association