---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-428306"
form_type: "8-K"
ticker: "KRRO"
cik: "0001703647"
company_name: "Korro Bio, Inc."
filed_at: "2026-10-22T11:04:13+00:00"
generated_at: "2026-10-22T11:05:05.013021+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# Korro's KRRO-111 shows 96% SERPINA1 editing, 95% liver Z-AAT cut; 1H 2027 filing planned

## Summary
- In NSG-PiZ mice, repeat-dose KRRO-111 reached 96% SERPINA1 mRNA editing, with M-AAT at 93% of circulating AAT and total AAT of 172 μM (~6-fold vs vehicle) at Day 57.
- In immunocompetent C57BL/6-PiZ mice, KRRO-111 reduced whole-liver Z-AAT by 95% versus vehicle at Day 57, measured by LC-MS/MS.
- Single-dose C57BL/6-PiZ: up to 91% editing and M-AAT up to 88% of total AAT, detectable through Day 42; EC50 ~1 nM, up to 98% editing in mouse and human hepatocytes.
- KRRO-111 is a subcutaneous GalNAc-conjugated oligonucleotide using ADAR to correct the pathogenic SERPINA1 transcript; Korro expects a regulatory submission in 1H 2027.
- CSO Loïc Vincent said the dual profile restores functional M-AAT while cutting toxic Z-AAT; CEO Ram Aiyar said Korro plans to advance KRRO-111 into the clinic in 1H 2027.

## SEC filing metadata
- accession: 0001193125-26-428306
- form_type: 8-K
- ticker: KRRO
- cik: 0001703647
- company_name: Korro Bio, Inc.
- filed_at: 2026-10-22T11:04:13+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1703647/000119312526428306/0001193125-26-428306-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1703647/000119312526428306/krro-20261022.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-428306
- JSON: https://secwatch.observer/filing/0001193125-26-428306.json
- Plain text: https://secwatch.observer/filing/0001193125-26-428306.txt

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