---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-23-198589"
form_type: "8-K"
ticker: "SPRO"
cik: "0001701108"
company_name: "Spero Therapeutics, Inc."
filed_at: "2023-07-31T23:59:59+00:00"
generated_at: "2026-06-12T22:09:55.845430+00:00"
event_type: "regulatory"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# FDA agrees to SPA for Spero's Phase 3 tebipenem HBr trial; $30M milestone due from GSK

## Summary
- FDA granted Special Protocol Assessment (SPA) for pivotal Phase 3 PIVOT-PO trial of oral tebipenem HBr vs IV imipenem in cUTI/acute pyelonephritis.
- Positive results from PIVOT-PO plus prior studies could support FDA approval for a limited use indication.
- Spero to receive $30M development milestone from GSK upon invoicing; additional milestones up to $495M plus tiered royalties.
- PIVOT-PO first patient first visit expected in Q4 2023; trial uses 10% non-inferiority margin per FDA guidance.
- SPR720 Phase 2 enrollment continues; top-line data now expected in H2 2024 (slower than prior guidance).

## SEC filing metadata
- accession: 0001193125-23-198589
- form_type: 8-K
- ticker: SPRO
- cik: 0001701108
- company_name: Spero Therapeutics, Inc.
- filed_at: 2023-07-31T23:59:59+00:00
- event_type: regulatory
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1701108/000119312523198589/0001193125-23-198589-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1701108/000119312523198589/d518650d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-23-198589
- JSON: https://secwatch.observer/filing/0001193125-23-198589.json
- Plain text: https://secwatch.observer/filing/0001193125-23-198589.txt

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