Ionis Expands Its Rare Epilepsy Pipeline With New ASCEND Trial in Dravet Syndrome

Ionis Pharmaceuticals Inc. (IONS) announced an update on their ongoing clinical study.

The ASCEND study, officially titled “Phase 1-2, Open-Label, Single and Multiple Ascending Dose Study to Evaluate Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Intrathecally-Administered ION337 in Patients With Dravet Syndrome,” aims to see if ION337 is safe for children with Dravet syndrome. The study is early stage but important, as it targets a rare and severe form of epilepsy with high unmet need.

The treatment being tested is ION337, an experimental drug given by injection into the fluid around the spine. It is designed to modify disease activity in Dravet syndrome and may reduce seizure burden if it proves safe and effective.

The study uses an open-label design, meaning all patients and doctors know they are receiving ION337. It is non-randomized and sequential, so patients move through single and then multiple dose levels mainly to check safety, not to compare against a placebo.

The trial started recruitment after submission on Apr. 8, 2026, marking the formal launch of this early program. The last update on Apr. 20, 2026 signals recent protocol activity, but primary and final completion dates are still ahead and will be key for the first real read on safety and dosing.

For Ionis Pharmaceuticals, Inc. (IONS), this update reinforces its push into severe neurological disease and expands its RNA-targeted rare disease pipeline. While near-term revenue impact is limited, positive safety signals could improve sentiment, support valuation for the neurology franchise, and add competitive pressure in the Dravet space where gene and small-molecule approaches are also emerging.

The ASCEND study of ION337 in Dravet syndrome is active and recruiting, with further details and ongoing updates available on the ClinicalTrials portal.

To learn more about IONS’s potential, visit the Ionis Pharmaceuticals Inc. drug pipeline page.