---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-22-032205"
form_type: "8-K"
ticker: "RGNX"
cik: "0001590877"
company_name: "REGENXBIO Inc."
filed_at: "2022-02-09T23:59:59+00:00"
generated_at: "2026-06-27T09:36:46.385116+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# REGENXBIO reports positive interim Phase I/II data for RGX-121 (MPS II) and RGX-111 (MPS I)

## Summary
- Both RGX-121 (13 pts) and RGX-111 (5 pts + single-patient IND) well-tolerated with no drug-related SAEs.
- RGX-121: Dose-dependent CSF biomarker reductions; Cohort 3 D2S6 near normal levels at last follow-up.
- RGX-111: CSF heparan sulfate decreased in all 4 patients; IDUA enzyme detected in 3 of 4 post-dose.
- Neurodevelopmental improvement: RGX-121 patients (Cohorts 1-2) show skill acquisition up to 2 years; RGX-111 shows gains in younger and one older patient.
- Next steps: RGX-121 Cohort 3 expansion with cGMP material planned 1H2022; RGX-111 Cohort 2 expanded to enroll up to 6 more patients.

## SEC filing metadata
- accession: 0001193125-22-032205
- form_type: 8-K
- ticker: RGNX
- cik: 0001590877
- company_name: REGENXBIO Inc.
- filed_at: 2022-02-09T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1590877/000119312522032205/0001193125-22-032205-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1590877/000119312522032205/d276078d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-22-032205
- JSON: https://secwatch.observer/filing/0001193125-22-032205.json
- Plain text: https://secwatch.observer/filing/0001193125-22-032205.txt

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