Biogen and Ionis Discontinue Development of Investigational Drug for ALS

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Biogen and Ionis Pharmaceuticals, Inc. have jointly announced the termination of BIIB105 (ION541), an investigational antisense oligonucleotide (ASO) for amyotrophic lateral sclerosis (ALS), based on topline results from the Phase 1/2 ALSpire study. While BIIB105 successfully reduced the expression of ataxin-2 (ATXN2) protein in cerebrospinal fluid (CSF), it did not demonstrate efficacy in reducing plasma neurofilament light chain (NfL) levels, a marker of neurodegeneration and neuronal damage. Furthermore, BIIB105 did not show improvement in clinical outcome measures related to function, breathing, and strength.

Stephanie Fradette, Pharm.D., Head of the Neuromuscular Development Unit at Biogen, stated, “While BIIB105 lowered ATXN2 protein, it did not reduce neurofilament, which gives us confidence that BIIB105 did not slow the disease process. We are deeply grateful for the contributions of the study participants and remain committed to developing treatments that can meaningfully change the disease trajectory for people living with ALS.”

Frank Bennett, Ph.D., Executive Vice President and Chief Scientific Officer of Ionis, expressed gratitude to the ALS community and investigators involved in the study, stating, “Ionis continues to be committed to the ALS community and is advancing our Phase 3 ulefnersen program for people with the genetic form of the disease known as FUS-ALS.”