CAR-T is the pinnacle of personalised medicine as it has to be developed for each individual patient.

Firstly, parts of the immune system - specifically white blood cells called T-cells - are removed from the patient's blood.

They are frozen in liquid nitrogen and sent to laboratories in the United States.

There, the white blood cells are genetically reprogrammed so that rather than killing bacteria and viruses, they will seek out and destroy cancer.

They are now "chimeric antigen receptor T-cells" - or CAR-T cells.

Millions of the modified cells are grown in the lab, before being shipped back to the UK where they are infused into the patient's bloodstream.

The whole manufacturing process takes a month.

As this is a "living drug", the cancer-killing T-cells stay in the body for a long time and will continue to grow and work inside the patient.

Mike says the side-effects of his treatment were worse than either of his two batches of chemotherapy.

Short-term neurotoxicity, where the brain and nerves are affected, can lead to confusion, difficultly speaking and a loss of consciousness.

There are five days after the treatment, when Mike was on intensive care, that he cannot remember at all.