---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-24-013803"
form_type: "8-K"
ticker: "SYBX"
cik: "0001527599"
company_name: "SYNLOGIC, INC."
filed_at: "2024-02-12T23:59:59+00:00"
generated_at: "2026-06-06T04:16:46.174412+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 1.0
calibrated_materiality_score: 1.0
confidence: "high"
source: SEC EDGAR
---

# Synlogic discontinues PKU study after data review; to cease operations, cut ~90% workforce, evaluate strategic options

## Summary
- Synpheny-3 study of SYNB1934 for PKU discontinued; internal data review found it unlikely to meet primary endpoint; safety acceptable.
- Company will cease operations and explore strategic alternatives including acquisition, merger, reverse merger, sale of assets, or dissolution.
- Workforce reduced by ~90%; CEO Aoife Brennan to depart March 9, 2024; estimated $6M in severance costs.
- Cash, equivalents, and short-term investments at Dec 31, 2023: $47.7M (unaudited).

## SEC filing metadata
- accession: 0000950170-24-013803
- form_type: 8-K
- ticker: SYBX
- cik: 0001527599
- company_name: SYNLOGIC, INC.
- filed_at: 2024-02-12T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 1.0
- calibrated_materiality_score: 1.0
- confidence: high
- sec_items: 2.02, 2.05, 5.02, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1527599/000095017024013803/0000950170-24-013803-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1527599/000095017024013803/sybx-20240212.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-24-013803
- JSON: https://secwatch.observer/filing/0000950170-24-013803.json
- Plain text: https://secwatch.observer/filing/0000950170-24-013803.txt

## Key facts
- Executive change
  Aoife Brennan resigned as Director at SYNLOGIC, INC..
  - Action: resigned
  - Role: Director
  source text: Dr. Brennan also resigned from the Company’s Board of Directors, effective March 9, 2024.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1527599/000095017024013803/0000950170-24-013803-index.htm
- Executive change
  Aoife Brennan was terminated as President and Chief Executive Officer at SYNLOGIC, INC..
  - Action: terminated
  - Role: President and Chief Executive Officer
  source text: the Company and Aoife Brennan, M.B. Ch.B., the Company’s President and Chief Executive Officer, agreed on February 8, 2024 that Dr. Brennan’s employment with the Company will terminate effective as of March 9, 2024.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1527599/000095017024013803/0000950170-24-013803-index.htm
- Restructurings & Charges
  SYNLOGIC, INC. announced a restructuring with charges of approximately $6 million affecting corporate (approximately 90%).
  - Type: restructuring
  - Charge: approximately $6 million
  - Affected area: corporate
  - Headcount: approximately 90%
  source text: On February 8, 2024, the Company announced that it is implementing a reduction in workforce by approximately 90%. The decision was based on cost-reduction initiatives intended to reduce the Company’s ongoing operating expenses and maximize shareholder value as the Company plans to pursue strategic options. The Company expects to complete substantially all of the reduction in workforce by the end of the fiscal quarter ending March 31, 2024. The Company estimates that it will incur approximately $6 million of costs in connection with the reduction in workforce related to severance pay and other related termination benefits.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1527599/000095017024013803/0000950170-24-013803-index.htm

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