Turnstone Biologics was a clinical-stage biotech developing cancer immunotherapies for solid tumors, centered on its "Selected TIL" (Tumor Infiltrating Lymphocyte) platform. TIL therapy involves extracting T cells from a patient's own tumor, expanding them outside the body, and reinfusing them to attack the cancer. Turnstone's approach differed from conventional TIL therapy by selecting only the most tumor-reactive T cells, rather than expanding the full T cell population. Its lead candidate, TIDAL-01, was being evaluated across breast cancer, colorectal cancer, uveal melanoma, and cutaneous melanoma. Turnstone never generated revenue and funded operations entirely through capital raises, totaling approximately $449.8M since inception, including an IPO in July 2023 that raised approximately $87.8M. The company is now effectively a shell in wind-down mode: in January 2025, Turnstone discontinued all clinical studies for TIDAL-01, and as of March 2025, it had only 14 full-time employees. The board is exploring strategic alternatives including a merger, asset sale, or other business combination, assisted by a financial advisor. Turnstone's residual value lies in its TIL therapy and oncolytic virus intellectual property and cash on hand. The company also faces potential Nasdaq delisting due to its stock price falling below the $1.00 minimum bid requirement.