Turnstone Biologics

Turnstone Biologics is a clinical-stage biotechnology company established in 2014, with a primary focus on developing immunotherapies for solid tumors. The company was founded by Ontario-based medical researchers Dr. John Bell, Dr. David Stojdl, and Brian Lichty, leveraging discoveries from multiple Canadian academic institutions. Initially incorporated in Canada, Turnstone reorganized as a Delaware corporation in December 2018 and is now headquartered in La Jolla, California.

The company's core technology revolves around a differentiated approach to tumor-infiltrating lymphocyte (TIL) therapy. Unlike traditional bulk TIL methods, Turnstone's proprietary process identifies, selects, and expands the most potent tumor-reactive T-cells, referred to as Selected TILs. This method is designed to overcome the limitations of first-generation TIL therapies and to be applicable across a broader range of solid tumors. The company's business model is centered on the research and development of these cell therapies, with the goal of bringing new medicines to cancer patients. Its lead product candidate, TIDAL-01, was being evaluated in Phase 1 clinical trials for various cancers, including breast cancer, colorectal cancer, and melanoma.

Turnstone has navigated a dynamic financial path, securing significant venture capital before going public. The company raised a total of $172 million in private funding over four rounds, including a notable $80 million Series D financing in June 2021 co-led by PFM Health Sciences and Point72. In July 2023, Turnstone completed an upsized initial public offering (IPO) on the Nasdaq, raising approximately $80 million. However, the company has faced challenges, including the termination of partnerships with major pharmaceutical firms like AbbVie and Takeda. In January 2025, following a strategic review, Turnstone announced the discontinuation of all TIDAL-01 clinical studies and initiated a process to explore strategic alternatives to maximize shareholder value. This followed a corporate restructuring in late 2024 that included a significant workforce reduction to extend its financial runway.

Keywords: TIL therapy, immunotherapy, solid tumors, oncology, clinical-stage, cell therapy, tumor-infiltrating lymphocytes, viral immunotherapy, cancer research, biotechnology