From $100M IPO to Liquidation in Five Years

It landed at 0.0558.

To put that in sports terms: IO Biotech's shot hit the rim, bounced twice, and rolled out. The difference between success and failure was razor-thin, but in drug development, close doesn't count. The trial technically missed its primary endpoint for progression-free survival, and that changed everything.

The FDA Slammed the Door

IO Biotech had been planning to file for FDA approval by the end of 2025. But at a pre-submission meeting on September 29, 2025, the agency recommended the company not bother submitting. The data, the FDA said, wasn't strong enough.

No application was ever filed. No formal rejection letter was ever issued. The FDA simply told IO Biotech: don't even try. That's arguably worse than a rejection, because it meant the agency saw no path forward with the existing data.

The company publicly said it would design a new study and keep talking to the FDA. Behind the scenes, the math was brutal. Running another large Phase 3 trial would cost hundreds of millions of dollars, and IO Biotech's cash was draining fast.

The Dominoes Fell Fast

What followed was a textbook biotech death spiral, compressed into just a few months.

The stock cratered. Shares plunged 46.5% in a single session after the company announced it was exploring "strategic alternatives" (the corporate euphemism for "we're running out of options"). Another day brought a 59.7% drop, shrinking the market cap to roughly $41 million. By the end, shares were trading at about six cents.

On January 21, 2026, IO Biotech formally announced it was looking at a merger, asset sale, or outright liquidation. On January 30, the company hired Raymond James as an advisor and implemented additional workforce reductions. But no buyer materialized. No white knight showed up.

On March 31, the company filed for Chapter 7 bankruptcy in Delaware. Not Chapter 11, which allows companies to reorganize and try again. Chapter 7 is the end of the road: total liquidation. The filing triggered automatic termination of every remaining employee, resignation of the entire board, and default on a €22.5 million loan from the European Investment Bank.

A Cautionary Tale With Broader Implications

IO Biotech's collapse is painful on its own. But it also carries a warning for one of biotech's hottest sectors.

Cancer vaccines are having a moment. Moderna's personalized mRNA vaccine (mRNA-4157) showed a 49% reduction in cancer recurrence risk in a Phase 2b melanoma trial and is now in Phase 3. BioNTech is running its own cancer vaccine program with Roche. Investor excitement is palpable.

But the IO Biotech story exposes the brutal math underneath that excitement. Even when a cancer vaccine shows a real clinical benefit (remember, 19.4 months vs. 11 months is no small thing), a narrow miss on statistical significance can turn a promising therapy into a bankrupt company overnight.

The broader field faces its own headwinds, too. Personalized cancer vaccines can take three months or more to manufacture for each patient, and there are no clear regulatory standards for testing their potency. The FDA is clearly willing to hold a hard line: just ask ImmunityBio, which received a refuse-to-file letter in May 2025 for its cancer immunotherapy, sending its stock to a 52-week low.

What's Left Behind

IO Biotech raised roughly $100 million in its 2021 IPO. It pulled in another €127 million in Series B. All of that capital, plus the years of scientific work that began in 2014, is now being parceled out by a bankruptcy trustee.

The T-win platform, whatever its merits, will likely be sold to the highest bidder for pennies on the dollar (if anyone bids at all). The science behind Cylembio isn't necessarily dead; it just needs a new home and, more importantly, a new trial with tighter statistics.

For the cancer vaccine sector, the lesson is uncomfortable but important: biology can be right even when the statistics say no. And in biotech, the statistics are all that matter. IO Biotech's vaccine may have genuinely helped patients live longer without their cancer worsening. But at p=0.0558, it doesn't matter. The company is gone, and the patients who might have benefited from a second, larger trial will never get the chance.

That 0.0108 difference between success and failure is the cruelest number in drug development.