See what I did there?
Immunocore has found a way of designing small protein molecules, which it calls ImmTACs, that effectively act as double-ended glue. At one end they stick to cancer cells, strongly and very specifically, leaving healthy cells untouched. At the other end they stick to T-cells.
The technology is based on the “T-cell receptor”, the protein that sticks out of the surface of the T-cell and binds to its enemy target. Immunocore’s ImmTACs are effectively independent T-cell receptors that are “bispecific”, meaning they bind strongly to cancer cells at one end, and T-cells at the other – so introducing cancer cells to their nemesis.
“What we can do is to use that scaffold of the T-cell receptor to make something that is very good at recognising cancer even if it doesn’t exist naturally,” said Dr Jakobsen. “Although T-cells are not very keen at recognising cancer, we can force them to do so. The potential you have if you can engineer T-cell receptors is quite enormous. You can find any type of cell and any kind of target. This means the approach can in theory be used against any cancer, whether it is tumours of the prostate, breast, liver or the pancreas.
The key to the success of the technique is being able to distinguish between a cancer cell and a normal, healthy cell. Immunocore’s drug does this by recognising small proteins or peptides that stick out from the surface membrane of cancer cells. All cells extrude peptides on their membranes and these peptides act like a shop window, telling scientists what is going on within the cell, and whether it is cancerous or not.
“All these little peptides tell you the story of the cell. The forest of them on the cell surface is a sort of display saying ‘I am this kind of cell. This is my identity and this is everything going on inside me’,” Dr Jakobsen explained.
Immunocore is building up a database of peptide targets on cancer cells in order to design T-cell receptors that can target them, leaving healthy cells alone and so minimising possible side effects – or that is the hope.
The first phase clinical trial of the company’s therapy, carried out on a small number of patients in Britain and the United States with advanced melanoma, has shown that people can tolerate the drug reasonably well and preliminary results suggest there are “early signs of anti-tumour activity”, the company said.
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