As the first – and so far only – drug to enter clinical testing for the rare neurogenetic disorder Alexander disease, there were some unknowns heading into the readout of the pivotal study testing Ionis Pharmaceuticals Inc.’s zilganersen in children and adults. But the top-line data yielded a clear win for the antisense oligonucleotide candidate, which demonstrated a disease-modifying impact, including statistical significance on the primary endpoint of gait speed as assessed by the 10-Meter Walk Test vs. control at week 61.

Down syndrome (DS) is the most prevalent genetic cause of Alzheimer’s disease (AD). Previous evidence suggests that increased dosage of the amyloid precursor protein (APP) gene plays a crucial role in AD in individuals with Down syndrome (DS-AD), making APP expression a crucial therapeutic target.