---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-23-007138"
form_type: "8-K"
ticker: "KRRO"
cik: "0001703647"
company_name: "Korro Bio, Inc."
filed_at: "2023-03-10T23:59:59+00:00"
generated_at: "2026-06-18T05:36:15.208465+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Frequency Therapeutics discontinues hearing programs, cuts 55% staff after Phase 2b miss, shifts to MS remyelination

## Summary
- FX-322-208 Phase 2b for hearing loss failed primary endpoint; company ends both FX-322 and FX-345 programs.
- New focus on MS remyelination program; targets clinical development initiation in first half of 2024.
- Restructuring reduces workforce by ~55%, completed by end of April 2023; cash runway extended into 2025.
- Q4 2022 net loss $17.4M; full year net loss $81.6M; cash, equivalents & marketable securities $83.1M at Dec 31, 2022.
- CEO David Lucchino returned from medical leave on March 1, 2023 and resumed all prior duties.

## SEC filing metadata
- accession: 0000950170-23-007138
- form_type: 8-K
- ticker: KRRO
- cik: 0001703647
- company_name: Korro Bio, Inc.
- filed_at: 2023-03-10T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 2.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1703647/000095017023007138/0000950170-23-007138-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1703647/000095017023007138/freq-20230310.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-23-007138
- JSON: https://secwatch.observer/filing/0000950170-23-007138.json
- Plain text: https://secwatch.observer/filing/0000950170-23-007138.txt

## Key facts
- Earnings Releases
  Korro Bio, Inc. reported Fourth Quarter and Full Year 2022 results: net income Net loss was $17.4 million for the three months ended December 31, 2022, as compared to $21.5 million for the comparable.
  - Period: Fourth Quarter and Full Year 2022
  - Net income: Net loss was $17.4 million for the three months ended December 31, 2022, as compared to $21.5 million for the comparable
  - Result: reported results
  source text: Net loss was $17.4 million for the three months ended December 31, 2022, as compared to $21.5 million for the comparable period of 2021. Net loss was $81.6 million for the full year ended December 31, 2022, as compared to $84.7 million for the comparable period of 2021.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1703647/000095017023007138/0000950170-23-007138-index.htm

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