IO Biotech, Inc. (IOBT)

IO Biotech, Inc. was a clinical-stage biotechnology company developing immune-modulating cancer vaccines. It was founded in 2014 by Mai-Britt Zocca and Inge Marie Svane, and its operating base was in Copenhagen, Denmark, with U.S. activity supporting its clinical programs. The company's science centered on T-win, a platform that uses peptide-based vaccines to direct T cells against proteins that tumors use to suppress the immune response.

Its lead candidate, IO102-IO103, targeted indoleamine 2,3-dioxygenase (IDO) and programmed death-ligand 1 (PD-L1), two proteins involved in immune suppression within the tumor environment. The product was studied in combination with the checkpoint inhibitor pembrolizumab (Keytruda) in patients with advanced melanoma in a Phase 3 trial, and in earlier-stage studies across other cancers. A second candidate, IO112, was directed at arginase 1.

IO Biotech completed an initial public offering on Nasdaq in November 2021, trading under the symbol IOBT. Like most clinical-stage companies it had no product revenue, financed its work through equity offerings and a loan facility, and reported recurring operating losses. The Phase 3 melanoma trial was the company's main value driver and its largest expense.

The Phase 3 results announced in 2025 showed a numerical improvement over pembrolizumab alone but did not reach the statistical significance threshold set for the primary endpoint. Following discussions with the U.S. Food and Drug Administration, the company said the agency did not support a filing based on that data. The company then cut staff and explored financing and strategic alternatives as its cash position declined.

In early 2026, IO Biotech filed for protection under Chapter 11 of the U.S. Bankruptcy Code and said it planned to sell its assets. On March 31, 2026, Nasdaq staff notified the company that it was no longer qualified for listing under Listing Rules 5101, 5110(b) and IM-5101-1, which give the exchange discretion to delist companies in bankruptcy or whose continued listing is not in the public interest.

The company did not appeal the staff decision, so trading in its common stock was suspended on April 7, 2026 and the determination became final. The shares moved to over-the-counter quotation under the symbol IOBTQ. Nasdaq issued the formal delisting determination on May 11, 2026, and removal from listing took effect at the opening of trading on June 18, 2026. Equity holders are generally not expected to receive substantial recoveries in a liquidating Chapter 11 case. Following the sale process, the company's remaining operations would be wound down or transferred under court supervision, and the shares are no longer eligible for trading on any national exchange.