---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-22-182828"
form_type: "8-K"
ticker: "SPRO"
cik: "0001701108"
company_name: "Spero Therapeutics, Inc."
filed_at: "2022-06-27T23:59:59+00:00"
generated_at: "2026-06-24T22:57:49.070748+00:00"
event_type: "regulatory"
sentiment: "negative"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# FDA rejects Spero's tebipenem HBr NDA for cUTI; additional clinical study required

## Summary
- Received Complete Response Letter on June 27, 2022 for tebipenem HBr oral tablets cUTI NDA.
- FDA determined Phase 3 ADAPT-PO study insufficient; additional clinical study needed.
- Company plans to request a Type A meeting with FDA to discuss path forward.
- CEO expressed disappointment but commitment to pursue regulatory approval and potential partnerships.

## SEC filing metadata
- accession: 0001193125-22-182828
- form_type: 8-K
- ticker: SPRO
- cik: 0001701108
- company_name: Spero Therapeutics, Inc.
- filed_at: 2022-06-27T23:59:59+00:00
- event_type: regulatory
- sentiment: negative
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1701108/000119312522182828/0001193125-22-182828-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1701108/000119312522182828/d373789d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-22-182828
- JSON: https://secwatch.observer/filing/0001193125-22-182828.json
- Plain text: https://secwatch.observer/filing/0001193125-22-182828.txt

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