Anthony Nolan_Hospital_RB_July 9_222

What is CAR T-cell therapy?

This is a brief guide to Chimeric Antigen Receptor T-cell (CAR T-cell) therapy, a type of treatment you may be offered if previous treatment, such as chemotherapy, is unsuccessful. CAR T-cell therapy is an evolving treatment and is currently only available for specific types of blood cancer.

What’s on this page?

What are CAR T-cells?

T cells are a type of white blood cell that form an important part of your immune system. They recognise abnormal cells, such as cancer cells, and destroy them.

T cells destroy abnormal cells using proteins on their surface called receptors. They bind to proteins found on cancer cells but not on normal cells. Sometimes, cancer cells can survive by disguising themselves from being recognised by T cells.

T cells become CAR T-cells when scientists change the DNA of T cells to make them produce a new type of receptor, called a Chimeric Antigen Receptor (CAR).

CAR T-cells are more efficient at binding to and removing cancer cells. They also send out signals that attract other immune cells and cause them to rapidly reproduce near the cancer cells. This increases the chance of all the cancer cells being removed.

Who can have CAR T-cell therapy?

There is specific eligibility criteria for CAR T-cell therapy. You should discuss with your doctor or clinical nurse specialist (CNS) if you think you are eligible.

CAR T-cell therapy has been approved to treat:

  • children and adults with relapsed or refractory B cell acute lymphoblastic leukaemia (ALL)
  • adults with B cell lymphoma, specifically:
    • relapsed or refractory diffuse large B cell lymphoma (DLBCL)
    • relapsed or refractory primary mediastinal large B cell lymphoma (PMBCL)
    • relapsed or refractory mantle cell lymphoma (MCL), where previous therapy includes a BTK-inhibitor.


CAR T-cell therapy is currently only offered if other treatments have been unsuccessful.

There are lots of other CAR T-cell therapies being tested in clinical trials right now. If the results are positive, these therapies may be available to more patients in the future.

You can have CAR T-cell therapy at a number of hospitals in the UK. You can find a list of these hospitals on the NHS website.

What happens during CAR T-cell therapy?

Collecting your T cells

Your T cells will be collected during a common procedure called apheresis. This can take a few hours. It may be need to be done over a period of two days to make sure enough T cells are collected.

  1. You'll have a needle in each arm (or you may have a central line in your chest).
  2. Your blood will be taken out of one arm and go into an apheresis machine.
  3. The apheresis machine will separate your T cells from the rest of your blood.
  4. The rest of your blood will be returned to your other arm.
  5. Your T cells are then sent to the laboratory where they are isolated and modified.

Forming your treatment

At the laboratory:

  1. Scientists will create your new CAR T-cells by modifying the DNA of your T cells.
  2. The cells will then be grown until there is enough of them to form your treatment. This can take a few weeks.
  3. When your CAR T-cells are ready, they will be frozen and sent back to the hospital, ready for you to receive.

Occasionally, the laboratory isn’t able to manufacture the CAR T-cells successfully. If this happens then your doctor will discuss options with you.  

Before you receive your new cells

While your CAR T-cells are being made, you will undergo physical health tests such as a heart scan and lung function test. It is likely that you may also need chemotherapy or radiotherapy, known as bridging treatment during this time, to try and keep the cancer under control.

When the CAR T-cells are ready, your CAR T team will let you know and prepare you for admission.

6-7 days before your CAR T-cells are infused, you will be given a course of chemotherapy known as conditioning therapy. This reduces the number of T cells in your body, makes space for your CAR T-cells, and prepares your body for treatment.

Treatment day

Your CAR T-cells will be thawed and your nurse will give them to you through your central line. This is called infusion. It’s a similar process to having a blood transfusion and should take about 30 minutes. You will also be given medication before the infusion to prevent any allergic reactions.


The CAR-T infusion can be delayed if you have signs or symptoms of infection. Your doctor will talk to you about this.

You will be monitored in hospital for about 10-14 days while you recover after your infusion.

You can be discharged if:

  • you have recovered from any side effects
  • are no more than an hour’s drive from the hospital (in case you experience any side effects)
  • you have someone to care for you at home.

If you do not meet the above criteria, you will stay in hospital for 28 days after your infusion.

Are there any side effects of CAR T-cell therapy?

CAR T-cell therapy is a very intensive treatment that will have a big physical and emotional impact on your life.

After treatment, your medical team will monitor you closely because most side effects develop within the first few days – but some could occur up to eight weeks later. Side effects will vary from person to person but may include the following:

Cytokine release syndrome (CRS)

When CAR T-cells enter your body, they activate other cells in your immune system that help remove cancer cells. Sometimes this signalling can cause an inflammatory response across the whole body, known as cytokine release syndrome.

Symptoms of CRS include:

  • flu-like symptoms
  • high fevers
  • low blood pressure

In very extreme cases, it can be life-threatening and you may need to be looked after on an intensive care unit.

Neurological problems

When lots of CAR T-cells are activated, they can affect your nervous system. This is called Immune Effector-cell Associated Neurotoxicity Syndrome (ICANS), or simply neurotoxicity.

Symptoms can vary from mild to severe. You might experience:

  • tremors
  • confusion
  • difficulty speaking
  • difficulty writing
  • difficultly moving
  • headaches
  • dizziness.

The nurses looking after you are trained to carry out neurological screening assessments. They will ask you various questions every day and will also assess your handwriting.

This might feel worrying but remember: your nurses and doctors are trained to manage these side effects and can treat ICANS with medications, such as steroids, if needed.

Neurotoxicity generally occurs within the first 28 days after infusion. There is a small risk of this happening beyond 28 days – up to eight weeks – so you are not allowed to drive for eight weeks after infusion.

Low B cell count

Some CAR T-cell therapies target cancerous B cells, but they may destroy healthy B cells as well. These cells are part of your immune system and help fight infections, which means after treatment you may be at risk of picking up an infection. It is important that you inform your medical team if you think you have an infection because you may need treatment for this.

Your medical team will talk to you about these side effects in more detail and give you advice on what to do if they start to develop. If you have any questions, they will be happy to answer them too.

Can I join a clinical trial?

Clinical trials are a type of medical research study. They test new treatments in a group of patients before they’re approved for the NHS to use. They’re based in either one or a few hospitals throughout the country and can only accept patients based on the type of blood cancer they have and their treatment history.

You can search for current clinical trials on the Find a clinical trial webpage on the Cancer Research UK website.

Unfortunately, if you don’t meet the medical criteria the trial needs, you won’t be able to take part. Your medical team will be able to talk to you about suitable trials when the time comes.

Will CAR T-cell therapy replace stem cell transplants?

For some patients, it's possible that CAR T-cell therapy may become an alternative to stem cell transplants in the future.

Other patients are likely to only be offered the treatment if their transplant is unsuccessful, or in addition to their transplant. Some may also go on to have a stem cell transplant if their CAR T treatment is unsuccessful.

Where can I read more about CAR T-cell therapy?

You can read more about CAR T-cell therapy, including from patients themselves, on the following websites:

Information published: 17/01/24

Next review due: 17/01/27