ION337 - (ASCEND)

July 13, 2026: Ionis Pharmaceuticals, Inc. (NASDAQ: IONS) announced dosing of the first participant in ASCEND (NCT07531745), an open-label Phase 1/2 trial of ION337, an investigational RNA-targeted splice-modulating antisense oligonucleotide for Dravet syndrome. ASCEND enrolls children ages 2–12 with a clinical diagnosis of Dravet syndrome and is evaluating safety and tolerability in a 6-month single ascending dose (SAD) phase, followed by a 24-month multiple ascending dose (MAD) phase with intrathecal dosing every 6 months, plus a 7-month safety follow-up.

ION337 is designed to increase NaV1.1 protein production in Dravet syndrome caused by certain SCN1A variants and uses Ionis’ next-generation N-methylacetamide (NMA) chemistry intended to enhance potency and support infrequent dosing. The FDA has granted ION337 Fast Track designation for treatment of Dravet syndrome.