IO Biotech admits defeat
After persevering with the IDO x PD-L1 immunotherapy Cylembio despite the project failing the Keynote-D18 first-line melanoma study, IO Biotech has now thrown in the towel. The company said on Wednesday that it was exploring “strategic alternatives”, and it’s notable that IO ran the clock right down to the wire: as recently as November the group was talking about meeting the FDA to discuss the design of a new phase 3 trial, but at the time it had less than $31m in the bank, only enough to get it into the first quarter of 2026. Perhaps IO thought that the December meeting could generate enough support for a fund raising, but no positive news has emerged. Keynote-D18 narrowly failed to meet its primary PFS endpoint in August, but IO had still hopes of a US filing; this plan was scuppered in September, when the FDA advised against a submission. Fresh hopes that the agency might be changing its stance were raised in October, when another company, Replimune, managed to refile its oncolytic virus therapy vusolimogene oderparepvec, but IO wasn't a beneficiary. The only other IDO x PD-L1 project in the clinic is Moderna’s mRNA contender mRNA-4359, in phase 1/2.
A Cylembio timeline
| Event | Date |
|---|---|
| Company announces that it’s “exploring strategic alternatives” | 21 Jan 2026 |
| During Q3 results, company disclosed plans to meet the FDA in December to discuss a new pivotal trial; cash of $30.7m, enough to fund through Q1 2026 | 14 Nov 2025 |
| Keynote-D18 results presented at ESMO; hopes of FDA change of heart spurred by Replimune resubmitting vuso-vec with FDA | 20 Oct 2025 |
| FDA advises company not to file Cylembio based on Keynote-D18; IO to design and run a new study, reduces workforce by 50% | 29 Sep 2025 |
| Keynote-D18 selected as an ESMO late-breaking abstract | 23 Sep 2025 |
| Keynote-D18 trial fails on its primary PFS endpoint (p=0.056); company to file with FDA by YE 2025 | 11 Aug 2025 |
Source: OncologyPipeline & company releases.
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