T-cells and brain cancer cell. Composite coloured scanning electron micrograph (SEM) of T-cells killing a brain cancer cell. STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY
ONE of the most amazing things about the immune system is how hard it works without you even being aware. It not only fights off bacteria and viruses every day, it also kills off most cancers long before they become a threat. But sometimes cancers manage to dodge the immune system – and a number of cancer therapies rely on restoring its effectiveness. An emerging star is CAR T-cell therapy, which has produced dramatic results for some cancers when all the usual treatments have failed.
This incredible technology relies on T-cells, immune cells that patrol our body, killing infected or cancerous cells. T-cells detect their targets with a receptor that protrudes from their surface and binds to a target protein, or a displayed fragment of a protein, on the outside of other cells. What this means is that if you add the right receptor to T-cells, you can make them target anything you want, including a cancer.
To achieve this, a person’s own T-cells are extracted and genetically modified to express a “chimeric antigen receptor”. This artificial receptor is made up of three proteins, one that recognises the cancer cell target and two that boost the T-cells’ activity.
Doctors multiply these cells and return them to their owner, where they seek out and destroy cells that have the target protein.
With a few of the first people treated still remaining free of cancer a decade later, it can now be said that, in some …
