BBC War on blood Still

What is CAR-T Therapy?

CAR-T therapy is a completely new type of therapy that uses the immune system to kill cancer cells. It is a personalised treatment, as it uses the patient’s own modified cells to destroy cancer cells.

T-cells are a type of immune cell that help the body fight infection by seeking out viruses, bacteria and parasites, and then killing them. T-cells also look for and destroy abnormal cells, such as cancer cells. Researchers have found that T-cells can be taken out of a patient’s body and genetically modified to boost their ability to recognise and kill specific cancer cells.

How does it work?

First, the patient has blood removed and the white blood cells are separated out, with the rest of the blood being returned to the patient.

The T-cells, a special type of immune cell, are then sent to a laboratory, where a harmless virus is used to insert genes into them.

These genes cause the T-cells to add a hook on to their surface, known as a chimeric antigen receptor (CAR). CAR are proteins that have been engineered to give T-cells the new ability to target a specific protein – in this case it is programmed to target the cancer cells.

These engineered CAR-T cells - programmed to recognise and destroy the patient's cancer cells - are multiplied in huge numbers and then infused back into the patient.

Who can have CAR-T cell therapy?

CAR-T therapy is designed for people with advanced or progressing blood cancers, who have limited treatment options open to them. It’s suitable for people with certain types of blood cancer who initially responded to treatment, but then relapsed (the cancer returned). It can also help those whose blood cancer is not responding to treatment (refractory or resistant disease).

What are the possible side effects of CAR-T therapy?

CAR-T is a new treatment for cancer patients and like all drugs, can cause side effects. The treatment is only conducted in specialist hospitals who have the skilled teams to support patients through the treatment.

Sometimes, CAR-T therapy can trigger side-effects, usually within five days of the infusion. Most patients will experience a mild reaction but in some cases it can be severe. Cytokine release syndrome can occur when immune cells activated by the treatment release an excessive amount of cytokines (small proteins that affect the behaviour of cells), resulting in a type of immune reaction similar to a severe infection.

This can lead to flu-like symptoms, such as: high fever and/or chills; racing heart beat; drop in blood pressure; and difficulty breathing. Neurological side effects can also occur, causing the patient to experience headaches, confusion, difficulty understanding language and speaking.

In almost all cases, these side-effects disappear within days or weeks and do not return.

Will CAR-T therapy cure blood cancer?

CAR-T is an exciting new treatment which has considerably changed the outlook for some people living with blood cancer. However, it is not appropriate for all types of blood cancer.

Unfortunately, for some patients who receive the treatment, not all respond. Why certain patients respond while others don’t is not well understood, and more research is needed.

More research also needs to be conducted in patients that do respond. As CAR-T therapy is a new treatment, we don’t have a complete picture on the long term side effects, and how long people’s response lasts.