# Turnstone Biologics

Source: https://onco.cc/companies/turnstone-biologics/  
OnCo record `turnstone-biologics` (Company). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Turnstone developed 'selected' tumour-infiltrating lymphocyte therapy, enriching the most cancer-reactive immune cells from a patient's tumour. It stopped its clinical programme in January 2025 and was bought by XOMA Royalty later that year.

## Summary

Turnstone Biologics was a San Diego biotechnology company that pioneered selected tumour-infiltrating lymphocyte (Selected TIL) therapy, enriching TIL populations for tumour reactivity. Its lead programme TIDAL-01 was studied in solid tumours and clinical data were presented at the SITC TIL Symposium in November 2024. In January 2025 the company discontinued all TIDAL-01 studies and halted development, then began a strategic alternatives process. On 27 June 2025 Turnstone agreed to be acquired by XOMA Royalty Corporation for $0.34 in cash per share plus a contingent value right; the tender offer and merger completed on 11 August 2025 and the Nasdaq listing (TSBX) ended. The company website no longer resolves.

## Fields

- Kind: Company
- Last checked: 2026-09-10
- HQ: San Diego, CA
- Type: cell-therapy

## Notes

- Former Nasdaq ticker TSBX. IPO (2023) not sourced.

## Sources

- Official website: https://www.sec.gov/edgar/browse/?CIK=0001764974
- XOMA acquisition agreement (8-K, June 2025): https://www.sec.gov/Archives/edgar/data/1764974/000119312525151306/d928306dex991.htm
- Completion of merger (8-K, August 2025): https://www.sec.gov/Archives/edgar/data/1764974/000119312525177597/d27108d8k.htm
- Q4 2024 results noting TIDAL-01 discontinuation (8-K): https://www.sec.gov/Archives/edgar/data/1764974/000095017025047107/tsbx-ex99_1.htm
- SEC EDGAR filings: https://www.sec.gov/edgar/browse/?CIK=0001764974

## Connected records

- fronts: [Cell Therapy](https://onco.cc/fronts/cell-therapy/)
- technologies: [TIL therapy](https://onco.cc/technologies/til-therapy/)

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JSON: https://onco.cc/api/v1/entities/turnstone-biologics.json