TSBX Turnstone Biologics Corporation

Turnstone Biologics Corp. (“Turnstone” or the “Company”) (Nasdaq: TSBX), a clinical-stage biotechnology company developing a differentiated approach to treat and cure patients with solid tumors by pioneering selected tumor-infiltrating lymphocyte (Selected TIL) therapy, today announced it will be presenting two posters highlighting preclinical data on methods for TIL selection at the Society for Immunotherapy of Cancer (SITC) 39th Annual Meeting being held November 6-10, 2024 in Houston, Texas.

“We remain confident that delivering a TIL-based product with a higher proportion of tumor-reactive T cells is the key to extending the clinical application of TILs across a broader range of solid tumors,” said David Stojdl, Ph.D., Turnstone’s Senior Vice President of Research. “At Turnstone, we are working relentlessly to expand the frontiers for TIL therapy by developing next-generation Selected TILs aimed at harnessing a greater reactive T cell population for more potent tumor killing. We look forward to sharing new preclinical results at SITC, which build on previous findings for TIDAL-01 and from within the field, highlighting the practicality of selecting and expanding tumor-reactive TIL as a potential treatment option for patients with critical unmet needs.”

Key findings from the two poster presentations follow, copies of which will be added to Turnstone’s website and can be accessed here.

Title: Enrichment of Neoantigen-Reactive Tumor-Infiltrating Lymphocytes (TIL) in Gastric CancerDate and Time: Saturday, November 9, 2024, 9:00am - 8:30pm CSTAbstract Number: 460In collaboration with H. Lee Moffitt Cancer Center (Moffitt)

• Turnstone’s 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 study utilized a scaled-down research model of clinical TIL isolation and demonstrated successful TIL expansion from gastric tumors. Additionally, the use of tumor-specific neoantigens allowed the enrichment of TIL, which maintained reactivity following expansion. These results demonstrate that reactive TIL enrichment protocols may enhance adoptive cell therapy with TIL for solid tumors.

Title: Overlap Between Circulating and Intratumoral T Cell Repertoire as a Predictor of Neoantigen-Reactive TIL Ex-Vivo ExpansionDate and Time: Friday, November 8, 2024, 9:00am - 8:30pm CSTAbstract Number: 443In collaboration with the University of Montreal Hospital Research Centre (CRCHUM)

• Although tumor-reactive TIL infused to patients are associated with clinical responses, there are currently no biomarkers that can predict whether tumor-reactive T cells can be expanded from a tumor.
• Using single T cell sequencing, this poster illustrates a manufacturing method tested to enrich TIL in tumor-reactive T cells, the results for which suggest that the degree of baseline TCR (T cell repertoire) overlap between blood and tumor repertoire could help identify patients from which tumor-reactive TIL can be expanded.

About Turnstone

Turnstone Biologics is a clinical-stage biotechnology company developing a differentiated approach to treat and cure patients with solid tumors by pioneering selected tumor-infiltrating lymphocyte (Selected TIL) therapy. Turnstone’s next-generation TIL therapy is based upon the identification, selection and expansion of the most potent tumor-reactive T cells, known as Selected TILs, and is designed to overcome the limitations of first-generation bulk TIL that have demonstrated objective responses only in limited tumor types. Turnstone’s clinical program, TIDAL-01, is currently being evaluated in multiple Phase 1 studies in patients with colorectal cancer, head and neck cancer, and uveal melanoma. For additional information about Turnstone, please visit www.turnstonebio.com, and follow us on LinkedIn.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements expressed or implied in this press release include, but are not limited to, statements regarding: the therapeutic potential for TIDAL-01; the potential for extended clinical applications of TILs across a range of solid tumors; the ability of TIDAL-01 to utilize a screening process to isolate and selectively expand the greatest breadth of the most potent tumor-reactive TIL; the potential for TIDAL-01 to be superior to current standard of care, if approved; and Turnstone’s strategies and objectives. All statements, other than statements of historical fact, contained in this press release, including statements regarding future events, future financial performance, business strategy and plans, and objectives for future operations, are forward-looking statements and can be identifies by terminology such as “anticipate,” “believe,” “contemplate,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “will” or “would,” or the negative of these terms or other comparable terminology. These statements are based on the current plans, objectives, estimates, expectations and intentions, beliefs and assumptions of our management team, and on information currently available to such management team and are not guarantees of future performance and inherently involve numerous risks and uncertainties, many of which are beyond Turnstone’s control. We undertake no obligation to update or revise publicly any of the forward-looking statements after the date hereof to conform the statements to actual results or changed expectations except as required by law. The reader is cautioned not to place undue reliance on forward-looking statements. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, but are not limited to, risks and uncertainties related to: macroeconomic conditions and the effects of global health concerns, such as global pandemics; Turnstone’s ability to initiate and execute clinical trials on the anticipated timelines, if at all; the potential for results from clinical trials to differ from preclinical, early clinical, initial, preliminary or expected results; the significant uncertainty associated with Turnstone’s product candidates ever receiving any regulatory approvals; Turnstone’s ability to obtain, maintain or protect intellectual property rights related to its product candidates; impediments to the Company’s ability to execute the workforce reduction as currently contemplated, the Company’s ability to achieve projected cost savings in connection with the workforce reduction, unintended consequences from the workforce reduction that impact the Company’s business; the sufficiency of Turnstone’s capital resources and need for additional capital to achieve its goals; and other risks, including those described under the heading “Risk Factors” in Turnstone’s Annual Report on Form 10-K or Quarterly Reports on Form 10-Q filed with the SEC and other documents Turnstone has filed, or will file, with the SEC. This press release discusses product candidates that are under clinical study and which have not yet been approved for marketing by the U.S. Food and Drug Administration. No representation is made as to the safety or effectiveness of these product candidates for the uses for which they are being studied.

Contact

Ahmed AneiziInvestor RelationsTurnstone Biologics(347) 897-5988ahmed.aneizi@turnstonebio.com