---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-129494"
form_type: "8-K"
ticker: "TSHA"
cik: "0001806310"
company_name: "Taysha Gene Therapies, Inc."
filed_at: "2025-05-28T23:59:59+00:00"
generated_at: "2026-05-20T08:32:42.209176+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.9
calibrated_materiality_score: 0.9
confidence: "high"
source: SEC EDGAR
---

# Taysha Gene Therapies Announces FDA Alignment on Pivotal Part B Trial Design for TSHA-102 in Rett Syndrome

## Summary
- 100% of 10 patients in Part A gained/regained ≥1 developmental milestone post-TSHA-102, with ~0% likelihood from natural history data.
- FDA supports single-arm open-label pivotal trial (N=15) with primary endpoint of developmental milestone gain/regain in patients ≥6 years.
- High dose outperformed low dose, with dose-dependent effects deepening over time; no treatment-related SAEs or DLTs.
- Analysis of IRSF natural history study (N~1100) showed patients ≥6 years in developmental plateau, <6.7% likelihood of milestone gain.
- Company expects to submit protocol this quarter and initiate pivotal trial in Q3 2025.

## SEC filing metadata
- accession: 0001193125-25-129494
- form_type: 8-K
- ticker: TSHA
- cik: 0001806310
- company_name: Taysha Gene Therapies, Inc.
- filed_at: 2025-05-28T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.9
- calibrated_materiality_score: 0.9
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1806310/000119312525129494/0001193125-25-129494-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1806310/000119312525129494/d904503d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-129494
- JSON: https://secwatch.observer/filing/0001193125-25-129494.json
- Plain text: https://secwatch.observer/filing/0001193125-25-129494.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.