Review: ‘Dark DNA’ peptideins and an early Ewing sarcoma vaccine trial

On 27 September 2026 BBC Science Focus published a long feature by Helen Pilcher on “dark DNA” — stretches of the genome long treated as non-coding that can encode very small proteins now often called peptideins (a working umbrella term used until function is proven and a molecule is upgraded to a microprotein). The piece synthesises interviews with researchers including Marie Brunet (Université de Sherbrooke), Sebastiaan van Heesch (Prinses Máxima Center, Utrecht) and John Prensner (University of Michigan).

What the science described

Ribosome profiling and related methods have shown that ribosomes translate thousands of unexpected genomic regions, pointing to a large class of tiny proteins beyond the roughly 20,000 classically annotated genes. A TransCODE consortium analysis cited in the article examined more than 7,000 previously ignored regions and estimated that about a quarter may produce peptideins — on the order of ~1,700 candidates — with at least ~50 suggested to play everyday cellular roles. Examples of upgraded tiny proteins include humanin (linked to cellular stress responses) and developmental microproteins such as tarsal-less in fruit flies.

In cancer, Prensner and colleagues are reported to find peptideins enriched in tumour cells; disabling the dark DNA that codes for some of them stopped growth in cultured breast, prostate, colorectal and brain cancer cells. Because HLA complexes display peptide fragments on cell surfaces, researchers are designing vaccines to train the immune system against cancer-associated peptidein fragments.

Ewing sarcoma vaccine — early stage

Van Heesch’s group designed a multi-fragment vaccine for Ewing sarcoma, a rare aggressive bone cancer that affects roughly 600 young people a year in Europe. The feature states an early-stage clinical trial funded by Fight Kids Cancer, with Institut Curie (Paris) and Heidelberg University Hospital, plans to enrol up to 45 patients. No efficacy results are claimed in the article; early-phase trials primarily assess safety and immune response.

Limits of this review

This is a review of a science-magazine synthesis, not a primary paper or trial readout. Peptidein biology is still maturing; many candidates lack proven function. The Ewing vaccine remains early clinical. This summary is not personal medical advice — discuss experimental oncology options only with a treating specialist.