Immune cells trained to kill leukaemia cells

Four patients with acute myeloid leukaemia are in remission after being transfused with immune cells harvested from donor blood which underwent a “boot camp” to kill cancer cells.

Researchers from the US and the Netherlands published the results of the small clinical trial in Science Translational Medicine.

Acute myeloid leukaemia is a blood cancer that affects mostly older people. But fewer than a third of patients are cured with standard therapies. For those who can’t receive bone marrow transplants, the prognosis is not good.

Could immunotherapy – a relatively new swag of treatments that have been shown effective in a number of cancers by rousing killer T-cells into action – help?

There are a few different immunotherapy methods. The first is to inject a patient with a vaccine to activate killer T-cells to recognise cancer cells and destroy them (much like a measles jab).

Another two involve harvesting T-cells from blood – the patient or a donor, depending on the disease. One technique multiplies and infuses the cells back into the patient to beef up defences while the other engineers the immune cells to recognise cancer cells. These are then multiplied and injected.

But enhancing immune cells while making sure they’re not rejected by the body, or ensuring they only target cancer cells and not healthy tissues, has been a huge challenge towards safe treatments.

In the current study, the team found that when combined with a cocktail of cell signalling molecules called cytokines, some killer T-cells become more deadly against acute myeloid leukaemia cells in a dish. And a single injection was enough to prolong the life of mice with the disease.

They then started a Phase 1 trial of nine patients with advanced acute myeloid leukaemia.

Donor blood was drawn, the T-cells removed and “trained” to remember and attack leukaemia cells, and injected into the bloodstream of the patients.

They saw low doses of the T-cells proliferated and stayed in the blood and bone marrow for weeks after the transfer. Four patients improved to the point of remission.

One patient achieved a partial remission, with some abnormal cells reappearing after a month. Of the remaining four, three died of blood infections before the end of the trial and one patient could not get enough T-cells from their donor.

It’s a small study, and the researchers acknowledge the treatment must be tested in a wider population, but their “promising” approach could give hope to patients with acute myeloid leukaemia and be tweaked to target other forms of cancer too.