---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-22-137586"
form_type: "8-K"
ticker: "SPRO"
cik: "0001701108"
company_name: "Spero Therapeutics, Inc."
filed_at: "2022-05-03T23:59:59+00:00"
generated_at: "2026-06-26T01:34:00.416189+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Spero halts tebipenem HBr commercialization, cuts workforce 75%; shifts focus to SPR720/SPR206

## Summary
- Immediately stopping tebipenem HBr commercialization after FDA indicated insufficient data for approval in current review cycle.
- Workforce reduction of ~75% (from 146 to ~35 FTEs); expects ~$8M in severance costs in Q2 2022.
- COO Cristina Larkin and CMO David Melnick separating; both to receive severance and remain as consultants for 10 months.
- Focus shifts to Phase 2-ready programs SPR720 (NTM lung disease) and SPR206 (MDR Gram-negative infections).
- Cash runway extended through late 2023; $146.4M in cash at Dec 31, 2021.

## SEC filing metadata
- accession: 0001193125-22-137586
- form_type: 8-K
- ticker: SPRO
- cik: 0001701108
- company_name: Spero Therapeutics, Inc.
- filed_at: 2022-05-03T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 2.05, 5.02, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1701108/000119312522137586/0001193125-22-137586-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1701108/000119312522137586/d241547d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-22-137586
- JSON: https://secwatch.observer/filing/0001193125-22-137586.json
- Plain text: https://secwatch.observer/filing/0001193125-22-137586.txt

## Key facts
- Executive change
  Cristina Larkin departed as Chief Operating Officer at Spero Therapeutics, Inc..
  - Action: separated
  - Role: Chief Operating Officer
  source text: Chief Operating Officer Effective as of July 2, 2022 (the "Effective Date"), Cristina Larkin will separate from the Company as its Chief Operating Officer pursuant to the Restructuring.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1701108/000119312522137586/0001193125-22-137586-index.htm
- Executive change
  David Melnick departed as Chief Medical Officer at Spero Therapeutics, Inc..
  - Action: separated
  - Role: Chief Medical Officer
  source text: Chief Medical Officer Effective as of the Effective Date, David Melnick, M.D. will separate from the Company as its Chief Medical Officer pursuant to the Restructuring.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1701108/000119312522137586/0001193125-22-137586-index.htm

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