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What is CAR-T therapy?

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Updated 13 Sep 2019

CAR-T therapy is a new type of cancer treatment that uses the immune system to kill cancer cells. In some cases it has cured people where all other treatments have failed. 

CAR-T therapy works by taking some T cells (blood cells that help to protect you from infection and disease) out of your blood, genetically modifying them in a lab so they are much better at finding and killing cancer cells, and then putting them back into your blood to fight the cancer. 

"Research has shown that CAR-T cells can remain in the body and continue to be active for a long period of time. So, unlike many other blood cancer drugs, CAR-T therapy is designed to be a one-time treatment." Professor Karl Peggs 

How is CAR-T therapy given? 

There are several stages in the process of having CAR-T therapy, which takes several weeks:

  • T cells are taken from your blood, using a tube inserted into a vein in your arm. This takes two to three hours.
  • T cells are taken to a laboratory and genetically modified, turning them into CAR-T cells. This takes two to three weeks.
  • CAR-T cells are put back into your bloodstream, through a drip. This takes a few hours.
  • CAR-T cells attack and kill cancer cells in the body. You will be closely monitored after having CAR-T therapy. 

Who can have CAR-T therapy? 

CAR-T therapy is still limited to a small number of people.  

In England, Scotland Wales and Northern Ireland, CAR-T therapy has been approved to treat: 

  • Children and adults up to the age of 25 with B-cell acute lymphoblastic leukaemia (ALL), whose first treatment has not worked 
  • Adults with types of non-Hodgkin lymphoma called diffuse large B-cell lymphoma (DLBCL) or primary mediastinal large B-cell lymphoma (PMBCL), whose lymphoma has continued to grow after at least two treatments  

There are currently two types of CAR-T therapy used in the UK made by two different companies. They are called Kymriah (tisagenlecleucel) and Yescarta (axicabtagene ciloleucel). 

Can everyone with these conditions get CAR-T therapy? 

Unfortunately not. Right now, CAR-T therapy is only a treatment option for certain blood cancers that haven’t responded to other standard treatments. There is also a high risk of side effects, so the person must have a certain level of fitness at the time of treatment.  

If you are eligible for CAR-T therapy 

If you think you may be eligible for CAR-T therapy and want to find out more, speak to your healthcare team.

If you are eligible, your doctor will refer you to both a local and a national CAR-T panel. The panel prioritises people eligible for CAR-T based on their fitness and severity of the cancer. 

How safe is CAR-T therapy? 

The CAR-T treatments approved for use in the UK have been through rigorous trials to make sure they’re as safe as possible for eligible patients. However, CAR-T therapy is still a new treatment and we’re learning with each clinical trial how to make it more effective. 

As with all cancer treatments, there are benefits and risks. As CAR-T is a new treatment, we don’t yet know if there are any longer-term risks. 

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

CAR-T therapy is still new and can cause some serious side effects. This is why the treatment is only done in specialist hospitals that have an expert team to manage these if they do occur. 

Cytokine release syndrome 

One of the more common side effects of CAR-T therapy (can occur in more than 1 in 10 people) is cytokine release syndrome (CRS). CRS is triggered when CAR-T cells release a substance called cytokine. This results in a type of immune reaction in the body similar to a severe infection and causes flu-like symptoms. It can usually be treated within a few days. 

Sometimes, CRS can become severe and dangerous, causing symptoms such as a high fever, fast heart rate, low blood pressure or difficulty breathing. 

Neurological side effects 

CAR-T therapy can also cause problems such as altered or decreased consciousness, delirium, confusion, agitation, seizures, difficulty speaking or understanding and loss of balance. Usually these symptoms get better on their own or respond to steroids.  

 How effective is CAR-T therapy? 

"CAR-T is an exciting new treatment that has considerably changed the outlook for some people living with blood cancer. However, it is not appropriate for all types of blood cancer, and not everyone with those cancers where it is available responds to this treatment. Why certain patients respond while others don’t is not well understood, and more research is needed.” Professor Karl Peggs. 

The CAR-T treatments being used in the UK have been shown to be better at getting people into remission than existing treatments. However, the evidence is still limited to the trials that have been done with specific groups of patients. We don’t know how well CAR-T works in large numbers of people, and we don’t know how well it works in many types and stages of blood cancer.  

Because CAR-T is a new treatment, we also don’t know what the longer-term impact is, in terms of response, survival and side effects.   

What CAR-T trials are currently happening in the UK? 

In addition to the CAR-T treatments explained here, which are now being used on the NHS, there are multiple other CAR-T treatments still being researched in clinical trials. They are looking at how to use CAR-T therapy to treat leukaemias, lymphomas and myeloma.  

To search for clinical trials, visit and search “CAR T” 

If you want to know more about clinical trials you may be eligible for, speak to your healthcare team. 

"Bloodwise is one of a small number of organisations funding CAR-T therapy trials. I am leading University College London's Bloodwise-funded COBALT trial, which is looking at the safety of a CAR-T therapy for people with an aggressive type non-Hodgkin lymphoma called diffuse large B cell lymphoma (DLBCL). The CAR-T therapy in this trial targets a protein called CD19 that’s found on the surface of some lymphoma cells. It’s a ‘bridging treatment’ for people with DLBCL, to get them into remission before a donor stem cell transplant." - Professor Karl Peggs. 

Keeping up-to-date with CAR-T 

We’ll keep this web page up-to-date with the latest information on CAR-T, and we’ll keep you informed about any changes or breakthroughs through our news blogs and social media.  

What are Bloodwise doing? 

We’re funding clinical trials into CAR-T so we can develop the treatment and make it available to more people. 

We supported the appraisal process for the new CAR-T treatments, helping to get them approved for use on the NHS for people with blood cancer.  

Now that some CAR-T therapies are being rolled out, we’re monitoring uptake closely, speaking to people who’ve had the treatment and the clinicians involved in their care. We want to understand how effectively it’s working and whether there are things that need to change to improve peoples’ experiences in future. 

Thank you to Professor Karl Peggs for working with Bloodwise to produce the videos and written content on this page. Professor Karl Peggs is Scientific Director of the  National Institute for Health Research (NIHR) Blood and Transplant Research Unit in Stem Cells and Immunotherapies, and Medical and Scientific Director of the Sir Naim Dangoor Centre for Cellular Immunotherapy at UCLH.

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