The FDA approves zilganersen by its September 22, 2026 PDUFA target action date.
Zilganersen has an FDA PDUFA target action date scheduled for September 22, 2026. The milestone is met if the FDA issues marketing approval by this deadline.
Across 6 frontier models answering independently, the panel leans yes: the median is 77%.
They do not agree: DeepSeek puts it at 88% and Claude at 58%, 30 points apart. A spread that wide usually means the question turns on something none of them can see yet.
It happened. Every model on the panel is now scored against that, and the market is scored on the same question.
It happened.
The FDA approved zilganersen (as Zanvastro) on September 3, 2026, which is before the September 22, 2026 PDUFA target action date. The statement asks whether FDA approved it 'by' the PDUFA date, meaning on or before that date, and the approval occurring earlier satisfies that condition.
Three models agreed on the evidence A search-grounded model gathered the sources below; three models from three different labs then ruled on that evidence independently and reached the same answer.
- Claudehappeneddirect evidence
- GPThappeneddirect evidence
- Geminihappeneddirect evidence
- FDA Approves First Drug to Treat Alexander Disease
- Novel Drug Approvals for 2026 - FDA
- ZANVASTRO™ (zilganersen) approved by the FDA as the first and only disease-modifying treatment
- Federal Register/Vol. 91, No. 195/Friday, October 9, 2026/ ...
- [PDF] Federal Register/Vol. 91, No. 195/Friday, October 9, 2026/Notices
- [PDF] ZANVASTRO™ (zilganersen) approved by the FDA as the first and ...
What each one said
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DeepSeekDeepSeek
PDUFA dates are met ~90%+ of the time; no known safety signal or CRL chatter 8 days out.
deepseek/deepseek-v4.1-flash · asked 14 Sept 202688% -
GeminiGoogle
Standard FDA approval rate for priority/orphan submissions near PDUFA is high given unmet medical need.
google/gemini-3.8-flash · asked 14 Sept 202682% -
GrokxAI
PDUFA actions usually land on-time; rare-disease NDA with positive P3 and no public delay flags.
x-ai/grok-4.6 · asked 14 Sept 202682% -
GPTOpenAI
With a near-term PDUFA date already set, timely approval is more likely than a delay or CRL.
openai/gpt-5.6-terra · asked 14 Sept 202671% -
QwenAlibaba
PDUFA approval rates ~85-90%, but zilganersen faces uncertainty around CMC/manufacturing and advisory committee concerns.
qwen/qwen3.8-max-0902 · asked 14 Sept 202662% -
ClaudeAnthropic
PDUFA dates hit roughly 60-70% of time absent known CRLs; no strong negative signal known here
anthropic/claude-sonnet-5 · asked 14 Sept 202658%
6 of 6 models answered · 30 points between the highest and lowest. None was shown the market price.
Question sourced from a news sweep on 14 Sept 2026. Forecast by google/gemini-3.8-flash, anthropic/claude-sonnet-5, openai/gpt-5.6-terra, x-ai/grok-4.6, deepseek/deepseek-v4.1-flash, qwen/qwen3.8-max-0902 via OpenRouter.