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Home › PDUFA Calendar › IONS

IONS PDUFA Date: Zilganersen (ION373)

Page updated ·next FDA decision on the calendar ·Data as of Oct 11, 2026 9:31 PM ET
✓ Approved · the FDA decided this application on September 3, 2026, 19 days before its September 22, 2026 goal date. Decision page with the source and measured reaction.
FDA decision Approved September 3, 2026 · Ionis Pharmaceuticals Inc. · Alexander disease
More CNS & Neurology FDA decisions →All September 2026 PDUFA dates →

The story

Zilganersen (ION373) was approved by the FDA on September 3, 2026 to treat Alexander disease. Balance sheet: about 25 months of cash, runway ~25 mo (estimated).
Full PDUFA calendar ->Every upcoming FDA decision date, by monthNRXP . 2026-07-29Same area: Neurology . KETAFREELNTH-florquinitau . 2026-08-13Same area: Neurology . Florquinitau (MK-6240)TLX . 2026-09-11Same month decision . TLX101-Px
Plain-English summary compiled by pdufa.bio from public FDA, SEC and company sources. Informational only - not investment advice.

IONS run-up into the PDUFA (last ~120 days)

$85.45$69.68
Price path to 2026-06-19. Green = local high, red = low/sell-off. Historical price action, not a forecast.

Key facts

FDA decisionApproved September 3, 2026
FDA goal date2026-09-22
Drug / candidateZilganersen (ION373)
IndicationAlexander disease
CompanyIonis Pharmaceuticals Inc.
Market-cap tierLarge
Cohort decision-day move (history)±1% median
ClinicalTrials.govNCT04849741 · Fast Track Designation (FTD)

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See the full 2026 PDUFA calendar →

FAQ

What did the FDA decide on IONS's Zilganersen (ION373)?
The FDA decided IONS's (Ionis Pharmaceuticals Inc.) application for Zilganersen (ION373) on September 3, 2026: Approved. The FDA goal date for this application was 2026-09-22. Verify against the linked primary source.
What is IONS's drug Zilganersen (ION373)?
Zilganersen (ION373) is Ionis Pharmaceuticals Inc.'s drug, approved by the FDA on September 3, 2026 for Alexander disease.
What typically happens to a large-cap stock into a PDUFA date?
Historically, large-cap names had a median decision-day move around ±1% (763-PDUFA cohort, 2024-26). This is historical context by market-cap tier, not a prediction for this drug.
Decision-day move · large-cap cohortn=790 · median +0.0% · 50% up
under -30%: 2 of 790 (0%)<-30-30 to -15%: 2 of 790 (0%)-15 to -7%: 6 of 790 (1%)-7 to -3%: 29 of 790 (4%)-3 to +3%: 707 of 790 (89%)±3+3 to +7%: 35 of 790 (4%)+7 to +15%: 5 of 790 (1%)+15 to +30%: 2 of 790 (0%)over +30%: 2 of 790 (0%)>+30
Distribution of next-day % moves after the FDA decision for large-cap PDUFAs (2020–26). Red = down, green = up, blue = flat (±3%). Historical dispersion, not a forecast.