Turnstone Biologics Corp. announced it will be presenting four posters highlighting preclinical data from its pipeline of programs, including the lead clinical candidate, TIDAL-01, at the Society for Immunotherapy of Cancer (SITC) 38th Annual Meeting being held November 1-5, 2023 in San Diego, California. Key findings from the four poster presentations follow, copies of which will be added to Turnstone?s website and can be accessed here.

Title: Expansion and Identification of Neoantigen-Reactive Tumor-Infiltrating Lymphocytes (TIL) from Metastatic Colorectal (CRC) and GI Cancers Date and Time: November 4, 2023, 9:00am - 8:30pm PT Abstract Number: 346 In collaboration with H. Lee Moffitt Cancer Center (Moffitt) Turnstone?s lead Selected TIL clinical candidate, TIDAL-01, utilizes a novel unbiased identification and functional screening process to isolate and selectively expand the greatest breadth of the most potent tumor-reactive (neoantigen-reactive) TIL from the patient?s tumor in vitro, before infusing them into the patient for more targeted tumor killing. This poster demonstrates that TIL from metastatic colorectal cancer and gastric cancer patient samples were successfully expanded from multiple disease sites in vitro. TIL from these samples were screened for neoantigens and enriched for neoantigen-reactive TIL, and furthermore, maintained reactivity following expansion.

These results, along with previous findings for TIDAL-01 and from within the field, highlight the practicality of selecting and expanding tumor-reactive TIL as a potential treatment option for colorectal and gastric cancer patients. Title: TBio BFX 4101: A Neoantigen Prioritization Pipeline for Selected Tumor-Infiltrating Lymphocyte Therapy Date and Time: Saturday, November 4, 2023, 9:00am - 8:30pm PT Abstract Number: 900 Identifying tumor-specific neoantigens arising from somatic mutations is one of the differentiating features of Turnstone?s Selected TIL process for TIDAL-01. In this poster, Turnstone presents TBio BFX 4101, a bioinformatics pipeline, which provides a comprehensive and efficient approach to identifying and ranking these neoantigens, with encouraging results from a variety of solid tumor samples, including melanoma, colon, and breast cancers.

Title: Tumor Neoantigen Prioritization from Liquid Biopsy Whole Exome Sequencing for Selected Tumor-Infiltrating Lymphocyte Therapy Date and Time: Saturday, November 4, 2023, 9:00am - 8:30pm PT Abstract Number: 178 In collaboration with Illumina Inc. Whole exome DNA and RNA sequencing were applied to patient liquid biopsy samples to assess the sensitivity of tumor variant detection and prioritization of neoantigen peptides in comparison with tissue data. This presentation highlights that minimally invasive liquid biopsy is viable for the detection of somatic variants in preclinical studies, and this approach to identifying neoantigens may increase the breadth and number of tumor-reactive T cells. Title: Enhancing Directly Selected Tumor-Reactive TIL Function Through Genetic Modification Date and Time: Saturday, November 4, 2023, 9:00am - 8:30pm PT Abstract Number: 350 Distinct from, yet complementary to TIDAL-01, Turnstone is developing a preclinical program associated with a next-generation direct selection process.

Direct selection utilizes a proprietary combination of markers designed to rapidly select for the greatest breadth of tumor-reactive T cells without the requirement for sequencing or peptide generation. Turnstone scientists are presenting preclinical data highlighting that directly selected tumor-reactive TIL can be genetically engineered using CRISPR-Cas and demonstrate that knocking out genes of interest can potentially enhance directly selected TIL quality and function.