CAR-T therapy: what it is, how it works, and who it can help

CAR-T therapy is an emerging type of immunotherapy that is being implemented for the treatment of certain cancers. In this article, a consultant haematologist with expertise in haemato-oncology explains this groundbreaking treatment.

What is CAR-T therapy?

CAR stands for “chimeric antigen receptor”, and it is a treatment that involves a “reprograming” of the T cells, which are a kind of white blood cell called lymphocytes that protect the body from infection and invasion.

T cells are a part of the body’s immune system, developing from stem cells in the bone marrow. They travel through the blood to find and kill abnormal cells. However, cancer can be difficult for the body and white blood cells to fight against because they cannot consistently recognise the cancer cells as malicious. Thus, CAR-T therapy was developed in order to “train” the T-cells to be more effective against cancer.

In the UK, there are three different types of CAR-T therapies available currently: tisagenlecleucel, axicabtagene ciloleucel, and brexucabtagene autoleucel.

How does CAR-T therapy work?

Some T cells are removed from the blood that has been extracted from the patient in a process called leukapheresis, and then genetically modified in a laboratory, which can take up to three weeks. Specialists imbue the T cells with a new gene, transforming them into CAR-T cells, which are then reinfused into the body via a drip over a few hours. Once released back into the bloodstream, they attack and wreak havoc on cancer cells as they are now able to detect them. Patients are closely monitored for the weeks after CAR-T therapy to track progress and keep an eye out for complications, which are not improbable.

CAR-T has been used in cases where all other treatments were unfruitful, providing new hope for cancer patients. The CAR-T cells will continue to multiply in the blood, acting as a long-term, “living” treatment against cancer.

Who can be treated with CAR-T therapy?

At the moment, CAR-T therapies are only effective against certain blood cancers, specifically leukaemia and lymphoma, and only in some cases.

The kinds of blood cancers it can be used for are:

• follicular lymphoma
• diffuse large B-cell lymphoma (DLBCL)
• B-cell acute lymphoblastic leukaemia (ALL)
• high-grade B-cell lymphoma
• mantle cell lymphoma
• multiple myeloma
• primary mediastinal large B-cell lymphoma

CAR-T therapies tend to be explored as an option after more common treatments have proven ineffective, as this is still a new technique with some serious possible side effects, such as too many cytokines in the blood (cytokine release syndrome or CRS), which are a chemical that stimulates the immune system but in excess, they can cause high fever, breathing issues, nausea and vomiting, palpitations, and muscle and joint pain. It can also disrupt the nervous system, causing headaches, seizures, confusion and loss of consciousness, comprehension and speaking difficulties, and loss of balance. That’s why it is only recommended for specific cases.

As an example, here are some of the circumstances that would be eligible for CAR-T therapy:

• children and young people up to 25 years old with ALL (specifically using tisagenlecleucel)
• adults with DLBCL or primary mediastinal large B-cell lymphoma whose lymphoma has continued to grow after at least two prior treatments, such as chemoimmunotherapy
• Adults with mantle cell lymphoma, whose lymphoma has continued to grow after two prior treatments
• Adults aged 26 and over with ALL, where treatment has not worked, or the ALL has come back after treatment

If you would like to know more about CAR-T therapy, or other blood cancer treatments, consult with a specialist on Top Doctors today.