Welcome to our dedicated page for Turnstone Biologics SEC filings (Ticker: TSBX), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
The TSBX SEC filings page on Stock Titan aggregates the historical regulatory filings of Turnstone Biologics Corp., which traded under the TSBX ticker before becoming a wholly owned subsidiary of XOMA Royalty Corporation and delisting from The Nasdaq Capital Market. These documents provide a detailed record of Turnstone’s operations as a clinical-stage biotechnology company focused on Selected tumor‑infiltrating lymphocyte (Selected TIL) therapy for solid tumors.
Through this page, users can access annual reports on Form 10‑K and quarterly reports on Form 10‑Q that describe Turnstone’s research and development activities, general and administrative expenses, net losses, risk factors, and discussion of its clinical programs such as TIDAL‑01. These filings offer insight into the company’s strategy, its focus on microsatellite stable colorectal cancer and other solid tumors, and the financial profile typical of a clinical-stage biotech.
The filings set also includes multiple current reports on Form 8‑K documenting material events. Examples include announcements of positive initial data from the Phase 1 STARLING trial, strategic restructuring and workforce reductions, the decision to discontinue all TIDAL‑01 clinical studies and explore strategic alternatives, and the Agreement and Plan of Merger with XOMA Royalty Corporation. Later 8‑K and 8‑K/A filings detail the tender offer, completion of the merger, change in control, and amendments to Turnstone’s charter and bylaws.
For trading and registration status, users can review the Form 25 filed by Nasdaq on August 11, 2025, which notifies the removal of Turnstone’s common stock from listing and/or registration on Nasdaq, and the Form 15 filed by Turnstone Biologics Corp. on August 21, 2025, certifying termination of registration of its common stock under Section 12(g) of the Exchange Act and suspension of reporting obligations under Sections 13 and 15(d). Together, these documents confirm that TSBX is a delisted and deregistered security.
Stock Titan’s platform surfaces these filings with AI-powered summaries that highlight key points from lengthy reports, helping users quickly understand clinical program disclosures, restructuring steps, merger terms, and changes in listing status. Real-time connections to the SEC’s EDGAR system ensure that historical updates are captured as filed, while structured access to Forms 10‑K, 10‑Q, 8‑K, 25, and 15 allows investors and researchers to trace the full regulatory history of Turnstone Biologics under the TSBX symbol.
Turnstone Biologics Corp. (TSBX) Form 4 shows that reporting persons affiliated with OrbiMed disposed of shares pursuant to an Agreement and Plan of Merger dated June 26, 2025. The transaction date reported is 08/08/2025. The purchaser is XOMA Royalty Corporation, which completed a cash tender offer paying $0.34 per share plus one non-transferable contractual contingent value right (CVR) per share.
The filing identifies 3,099,265 common shares in the ownership table and explains those shares are held of record by OrbiMed Private Investments VI, LP, with OrbiMed Capital GP VI LLC as general partner and OrbiMed Advisors LLC as managing member. The report is jointly filed by OrbiMed Advisors and GP VI and includes standard disclaimers about beneficial ownership and the designation of a board representative.
Turnstone Biologics Corp. agreed to be acquired by XOMA Royalty Corporation through a tender-offer merger structure culminating in a merger that made Turnstone a wholly owned subsidiary of XOMA. Versant-related stockholders (the "Versant Stockholders") participated in the Offer and aggregately tendered 3,381,692 shares of Turnstone common stock in exchange for $0.34 per share in cash and one non-transferable contractual contingent value right (CVR) representing potential milestone payments.
The Purchaser accepted for payment all validly tendered shares and, following satisfaction of the merger conditions, completed the merger so Turnstone survived as XOMA's wholly owned subsidiary. As a result, the reporting persons disclosed in this Amendment ceased to beneficially own more than 5.0% of Turnstone common stock.
Versant-affiliated entities reported dispositions of Turnstone Biologics common stock on 08/08/2025 pursuant to an Agreement and Plan of Merger dated June 26, 2025 under which XOMA Royalty Corporation completed a cash tender offer for all outstanding shares at $0.34 per share plus one non-transferable contractual contingent value right (CVR) per share. The Form 4 shows post-transaction indirect beneficial ownership retained by Versant vehicles: 2,726,322 shares held by Versant Venture Capital V, L.P., 207,486 by Versant Venture Capital V (Canada) LP, 90,888 by Versant Ophthalmic Affiliates Fund I, L.P., 82,006 by Versant Affiliates Fund V, L.P., and 274,990 by Versant Vantage II, L.P. The filing was signed on 08/12/2025 by Max Eisenberg as Chief Operating Officer.
Turnstone Biologics Corp. has filed post-effective amendments to withdraw and deregister all unsold shares that remained registered under two Form S-8 registration statements. The company removed a total of 7,003,706 unsold shares from registration, representing shares reserved under its 2018 Equity Incentive Plan, 2023 Equity Incentive Plan and 2023 Employee Stock Purchase Plan.
The deregistration follows a merger agreement under which Turnstone became a wholly owned subsidiary of XOMA Royalty Corporation, with XRA 3 Corp. as merger sub. As a result, the Registrant terminated the offerings contemplated by the S-8 registration statements and removed the unsold shares from registration as required by its prior undertakings. The post-effective amendments were signed by Owen Hughes, President, Treasurer and Secretary.
Turnstone Biologics Corp. filed post-effective amendments to its Form S-8 registration statements to remove from registration all shares that remain unissued and unsold following its merger into XOMA Royalty Corporation. The company entered into a Merger Agreement on June 26, 2025, and on August 11, 2025 Merger Sub merged into Turnstone, with Turnstone surviving as a wholly owned subsidiary of Parent. The amendments withdraw the unsold securities that had been registered for issuance under the 2018 Equity Incentive Plan, the 2023 Equity Incentive Plan and the 2023 Employee Stock Purchase Plan and terminate the effectiveness of the referenced registration statements.
The registration statements covered a combined 7,003,706 shares across both filings; the company states it is removing from registration all such unsold securities in accordance with its prior undertakings.
Turnstone Biologics entered into and completed a merger in which XOMA Royalty Corporation purchased the company in a two-part offer: $0.34 in cash per share plus one contingent value right (CVR) for each share. The tender offer expired on August 7, 2025 with 17,192,002 shares validly tendered, representing approximately 74% of outstanding shares; all tendered shares were accepted. After closing, Merger Sub merged into Turnstone, making Turnstone a wholly owned subsidiary of Purchaser and causing the surviving company to operate under Merger Sub’s amended charter and bylaws.
Unvested restricted stock units were accelerated to vest and then cancelled for the offer consideration; outstanding stock options were cancelled without consideration. Separately, Turnstone completed an asset sale to H. Lee Moffitt Cancer Center receiving approximately $3.0 million, with about $1.8 million placed into escrow and to be released following the merger. The surviving corporation requested Nasdaq suspension and delisting of the shares and plans to terminate public reporting and deregister the shares. The board of Turnstone resigned and Owen Hughes (previously sole director/officer of Merger Sub) became director and officer of the surviving corporation.
Turnstone Biologics completed a tender offer and merger after the offer expired at 11:59 p.m. ET on August 7, 2025. The Depositary reported 17,192,002 Shares were validly tendered and not withdrawn, representing approximately 74% of outstanding shares, satisfying the minimum condition. Purchaser accepted those Shares for payment and expects to promptly pay the Offer Price of $0.34 cash per share plus one CVR per share. The merger was consummated on August 11, 2025 under Section 251(h) of the DGCL without a stockholder vote. At the effective time, most outstanding Shares were cancelled and converted into the right to receive the Offer Price. Shares ceased trading before the market opened on August 11 and will be delisted, with the Purchaser intending to terminate registration and suspend reporting obligations.
Turnstone Biologics Corp. submitted a Form 25 notification concerning the removal of its Common Stock from listing and/or registration under Section 12(b) of the Securities Exchange Act. The filing identifies the issuer, the Nasdaq Stock Market LLC as the exchange, the issuer's address and telephone number, and Commission File Number 001-41747.
Nasdaq certifies it has reasonable grounds to file the Form 25 and includes statements of compliance with 17 CFR 240.12d2-2(b) and 12d2-2(c). The notice is signed by Jennifer Fainer, CDO Analyst on 2025-08-11. The filing does not state an effective delisting date nor clearly indicate which specific rule provision box was marked.
Turnstone Biologics has agreed to be acquired by XOMA Royalty Corporation in a transaction that will convert each outstanding share into a cash tender offer of $0.34 per share plus one contingent value right (CVR). Options will be cancelled and outstanding RSUs will be accelerated and settled for the same cash amount plus one CVR. The CVR entitles holders to a portion of specified contingent payments and certain Net Cash proceeds, with an aggregate contingency pool including up to $1.1 million tied to tax receivables and a lease security deposit; CVR payments received more than one year after closing will not be paid.
At June 30, 2025 the company held $16.7 million of cash and cash equivalents, reported a $17.3 million net loss for the six months, and an accumulated deficit of $264.9 million. Management believes cash on hand is sufficient to meet obligations for the next twelve months. Turnstone has substantially reduced headcount (reported as 3 employees at June 30, 2025 and subsequently 2 employees) and recorded restructuring charges and asset dispositions, including property and equipment held for sale and a recognized loss on disposal of $2.6 million for the six months.
Corporate actions include an Asset Purchase Agreement with Moffitt for approximately $3.0 million (about $1.8 million in escrow at signing), termination of its Banc of California loan facility without draws, and a transfer to the Nasdaq Capital Market with an additional 180-day cure period to regain a minimum $1.00 bid price. The Myst contingent milestone liability was revalued to $0, reflecting management’s updated probability assessment.