---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-24-000249"
form_type: "8-K"
ticker: "SPRO"
cik: "0001701108"
company_name: "Spero Therapeutics, Inc."
filed_at: "2024-01-02T23:59:59+00:00"
generated_at: "2026-06-07T05:20:46.818944+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Spero starts Phase 3 PIVOT-PO trial of tebipenem HBr; $95M milestone payable over two years from GSK

## Summary
- First patient first visit for Phase 3 PIVOT-PO trial (cUTI/AP) targeting ~2,648 patients.
- Primary endpoint: overall response (composite of clinical cure + microbiological eradication) at test-of-cure.
- Non-inferiority vs IV imipenem cilastatin with 10% NI margin in microbiological ITT population.
- GSK license: $95M development milestone payable in 4 equal semiannual installments over 2 years.
- Additional milestones: $25M on FDA submission, up to $150M commercial, up to $225M sales, plus tiered royalties.

## SEC filing metadata
- accession: 0001193125-24-000249
- form_type: 8-K
- ticker: SPRO
- cik: 0001701108
- company_name: Spero Therapeutics, Inc.
- filed_at: 2024-01-02T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1701108/000119312524000249/0001193125-24-000249-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1701108/000119312524000249/d360654d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-24-000249
- JSON: https://secwatch.observer/filing/0001193125-24-000249.json
- Plain text: https://secwatch.observer/filing/0001193125-24-000249.txt

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