The findings, by researchers funded by Cancer Research UK and the Rosetrees Trust, could guide future immunotherapies and improve the way existing immunotherapy drugs are used. As a tumour develops, the diversity of its genetic faults can be flagged on the cancer cell surface, as unique mutations appear in different parts of the tumour. Crucially, by analysing data from hundreds of patients from previous studies, researchers found that some of these flags — known as antigens — represent the very earliest mutations of the disease and are displayed on all cells in the tumour, rather than a subset of tumour cells.Then in the lab, they isolated specialised immune cells, called T-cells, from samples of two patients with lung cancer that can recognise these common flags present on every tumour cell. Although they have the potential to wipe out all cancerous cells within the tumour, these potent immune cells are switched off by the tumour’s defences. This research paves the way for therapies that specifically activate these T cells to target all the tumour cells at once based on the disease’s genetic signature. In the future, scientists could exploit this by developing a therapeutic vaccine to activate T-cells, or harvesting, growing and administering T-cells back into the patient that recognise the antigens common to every cancer cell.