---
schema_version: "secwatch.filing_event.v1"
accession: "0001745020-23-000073"
form_type: "8-K"
ticker: null
cik: "0001745020"
company_name: "Theseus Pharmaceuticals, Inc."
filed_at: "2023-11-13T23:59:59+00:00"
generated_at: "2026-06-08T05:18:18.099984+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Theseus Pharma lays off 72% of staff, explores strategic alternatives; cash $225.4M

## Summary
- Workforce reduction of ~72% (26 employees, including R&D President); severance costs ~$5.5M in Q4 2023.
- Process to explore strategic alternatives including potential sale of company or assets to maximize shareholder value.
- Cash, cash equivalents, and marketable securities total $225.4M as of September 30, 2023.
- President R&D William Shakespeare terminated without cause; receives $0.5M severance, accelerated equity vesting, consulting role through June 2024.

## SEC filing metadata
- accession: 0001745020-23-000073
- form_type: 8-K
- cik: 0001745020
- company_name: Theseus Pharmaceuticals, Inc.
- filed_at: 2023-11-13T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 2.02, 2.05, 5.02, 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1745020/000174502023000073/0001745020-23-000073-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1745020/000174502023000073/thrx-20231106.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001745020-23-000073
- JSON: https://secwatch.observer/filing/0001745020-23-000073.json
- Plain text: https://secwatch.observer/filing/0001745020-23-000073.txt

## Key facts
- Executive change
  William C. Shakespeare, Ph.D. was terminated as President of Research and Development at Theseus Pharmaceuticals, Inc..
  - Action: terminated
  - Role: President of Research and Development
  source text: the Company terminated the employment of William C. Shakespeare, Ph.D. as President of Research and Development of the Company, effective as of November 9, 2023 (the “Separation Date”), without cause.
  evidence_url: https://www.sec.gov/Archives/edgar/data/1745020/000174502023000073/0001745020-23-000073-index.htm
- Restructurings & Charges
  Theseus Pharmaceuticals, Inc. announced a restructuring with charges of $5.5 million (26 full-time employees, or approximately 72% of the Company’s then-current employee base).
  - Type: restructuring
  - Charge: $5.5 million
  - Headcount: 26 full-time employees, or approximately 72% of the Company’s then-current employee base
  source text: employee’s entering into an effective separation agreement, which includes a general release of claims against the Company. The reduction of workforce is expected to result in $5.5 million in severance costs. The incremental costs are expected to be incurred in the fourth quarter of 2023. --- EX-99.1 (EX-99.1) --- Theseus Pharmaceuticals Announces Process to
  evidence_url: https://www.sec.gov/Archives/edgar/data/1745020/000174502023000073/0001745020-23-000073-index.htm

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