What is CAR T-Cell therapy?

What is CAR T-cell therapy, and what does it mean for the future of cancer treatment?

Blood cancer is the third biggest cancer killer in the UK. However, a revolutionary immunotherapy treatment known as known as CAR T-cell therapy (Chimeric Antigen Receptor T-cell therapy) has brought renewed hope to blood cancer patients and the medical world alike.

Dubbed the ‘5th pillar of cancer treatment’ by many (following surgery, chemotherapy, radiotherapy and targeted therapies), CAR T-cell therapy is now available for eligible patients in the UK.

To help shed some light on this groundbreaking therapy, one of the UK’s leading experts on CAR T-cell therapy - Professor Stephen Mackinnon, Chair of the HCA Healthcare UK Blood Cancer Board has provided an overview on what CAR T-cell therapy is, how it works, and how it could transform the future of cancer treatment on a global scale.

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What is CAR T-cell therapy?

“CAR T-cell therapy is a revolutionary new type of cancer therapy for blood cancer patients. ”

Prof. Mackinnon

CAR T-cell therapy is a revolutionary new type of cancer therapy for blood cancer patients. The name refers to T-cells which have been modified with chimeric antigen receptors (CAR).

T-cells are a type of white blood cell which play a vital role in the immune system - orchestrating the immune response and killing cells infected by pathogens. During this process T-cells use their protein receptors to latch on to antigens found on the surface of other cells and examine them; the T-cell will move on if the examined cell is healthy or, when a diseased or cancer cell is discovered, T-cells release killer chemicals to destroy the abnormal cell. Unfortunately, cancer has the ability to evade and fool our immune system. It can do this by disguising itself as a healthy cell or by creating multiple abnormal antigens on its surface which prevent T-cell receptors latching on– giving the disease a chance to spread.

With CAR T-cell therapy, modified T-cells are specifically designed to strengthen and harness the immune system’s inherent cancer eliminating powers, adding new targeted receptors designed to seek, attach to and destroy cancer cells which may have previously gone undetected.

Firstly, the patient needs to have their T-cells isolated and collected. This process is like a blood donation. The blood is put through an apheresis machine to separate and collect the T-cells from the other blood cells, which are then returned to the body.

Following this, the separated T-cells are transported to a lab where they are engineered to express personalised and targeted CARs that recognise cancer cells, turning them into ‘CAR T-cells’.

These modified T-cells are then grown and expanded in a lab and millions of them are infused back into the patient following a short course of conditioning chemotherapy. Once the modified T-cells are back in the patient’s bloodstream their new receptors enable them to latch onto a specific antigen found on the patient’s tumour cells and destroy them.

How is the CAR T-cell therapy different to traditional immunotherapy?

The most advanced aspect of CAR T-cell therapy is that it works using the patient’s own engineered blood cells – there are no drugs involved! Traditional immunotherapy typically refers to when drugs are used to stimulate a patient’s immune system to seek and destroy cancer cells, but CAR T-cells remove the need for this. The fact that there are no drugs involved is a very exciting development. This is a ‘first of a kind’ therapy and is a huge moment for the treatment of cancer. It has the potential to revolutionise the approach to cancer treatment moving forward.

Who is suitable for CAR T-cell therapy?

CAR T-cell therapy is approved for the treatment of patients with Acute Lymphoblastic Leukemia, Transformed Follicular Lymphoma, Primary Mediastinal Large B-Cell Lymphoma and Diffuse Large B Cell Lymphoma. Due to the complex nature of the treatment the decision on which patients are eligible will be decided by a panel of expert clinicians following a referral from a specialist doctor.

Launching this spring at HCA Healthcare UK, CAR T-cell therapy will initially be available to patients with diffuse large B-cell lymphoma, primary mediastinal large B-cell lymphoma and transformed follicular lymphoma, with plans to extend the offering to other blood cancers over the coming months. We are excited to provide this innovative treatment to our patients in our JACIE-IEC accredited units.

Is CAR T-cell therapy effective?

The results from trials so far have been very positive – with some patients who have undergone the treatment showing signs of rapid and durable regression/remission which haven’t been seen previously. In some instances, complete remission has been observed. It is very exciting to see and demonstrates that CAR T-cell therapy will be a breakthrough treatment for many patients.

What does the future hold for CAR T-cell therapy?

Due to its revolutionary nature, the launch of CAR T-cell therapy marks a significant step forward in the way cancer can be treated, and what the future of treatment could look like for those suffering from multiple different types of the disease. There are many clinical trials underway at present and data from these trials will provide valuable insight into this treatments future potential.

Researchers are also currently working on a similar concept to CAR T-cell therapy for the treatment of solid cancer tumours (NAR T-cell therapy). This is another big step on, and it’s likely that the next decade will be highly transformative for cancer treatment.

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