---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-065633"
form_type: "8-K"
ticker: "SPRO"
cik: "0001701108"
company_name: "Spero Therapeutics, Inc."
filed_at: "2025-03-27T23:59:59+00:00"
generated_at: "2026-05-24T03:57:46.535489+00:00"
event_type: "earnings"
sentiment: "negative"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Spero posts Q4 net loss of $20.9M; revenue down 80% YoY; pipeline setbacks and SEC Wells Notice

## Summary
- Net loss of $20.9M in Q4 2024 vs net income of $51.2M in Q4 2023; diluted EPS loss of $(0.38).
- Total revenue fell to $15.0M from $73.5M YoY, driven by lower collaboration revenue from GSK and Pfizer.
- Tebipenem HBr Phase 3 PIVOT-PO interim analysis expected Q2 2025; SPR720 Phase 2a missed primary endpoint with three cases of grade 3 hepatotoxicity; SPR206 discontinued.
- Leadership change: Esther Rajavelu appointed Interim President and CEO in January 2025 following a Wells Notice from SEC related to disclosures in 2022.
- Cash of $52.9M as of Dec 31, 2024; plus GSK milestones provide runway into Q2 2026.

## SEC filing metadata
- accession: 0001193125-25-065633
- form_type: 8-K
- ticker: SPRO
- cik: 0001701108
- company_name: Spero Therapeutics, Inc.
- filed_at: 2025-03-27T23:59:59+00:00
- event_type: earnings
- 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/1701108/000119312525065633/0001193125-25-065633-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1701108/000119312525065633/d906623d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-065633
- JSON: https://secwatch.observer/filing/0001193125-25-065633.json
- Plain text: https://secwatch.observer/filing/0001193125-25-065633.txt

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