Otsuka and Ionis Pharmaceuticals reported positive phase III results from the Fusion study of ulefnersen in FUS-associated amyotrophic lateral sclerosis (ALS). The data showed statistically significant improvement in function and survival in patients with this rare ALS subtype that currently has no approved targeted therapies. The antisense oligonucleotide ulefnersen is designed to modify disease biology at the genetic level, and the phase III outcome positions the asset for potential expedited regulatory discussions. If regulators align with the evidence, the readout could accelerate progress toward precision medicine in rare ALS. For the field, the milestone is also a marker of continued investor and regulatory interest in antisense approaches as viable platforms in neurodegenerative diseases with defined genetic drivers.