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Chimeric antigen receptor t-cell therapy, or CAR-T therapy, is probably a term that you’ve been hearing a lot about recently. In August, CAR-T hit the headlines after the FDA approved its use in America for the treatment of acute lymphoblastic leukaemia (ALL) in patients up to the age of 25 years old and this month the treatment has again been approved in America for treatment of certain adulthood lymphomas.
The high price of the treatment caught the attention of the media, but there’s far more to consider with CAR-T therapy and much of it is very exciting.
- Success in treating blood cancers in patients who have relapsed or not responded to treatment (refractory).
The first approved CAR-T in America, named Kymriah, saw around 83% of ALL patients in remission after 3 months and this was sustained in a large number of patients without further intervention.
- A ‘living drug’ that can provide long-term therapy
Long-term studies detected CAR T-cells in the blood stream up to a decade after the first infusion. T-cells provide the immune response memory to damaged or foreign cells and therefore, if they remain in the blood stream an immune response to deal with the tumour cells can be continual and prevent a patient from relapsing.
- Personalised treatment to blood cancer
The main focus of CAR-T development is autologous CAR-T, meaning that a patient’s own T-cells are taken and genomic techniques are used to enable them to start an immune response against tumour cells. Tailoring treatment to a patient increases the likelihood of successful treatment.
As you can see CAR-T is seemingly a successful treatment option for patients who have exhausted current treatment options. However, there are problems with CAR-T therapy…
- Side effects – cytokine release syndrome (CRS)
When a t-cell interacts with a tumour cell, cytokines are released to signal that an immune response is required. Cytokines cause fever-like symptoms (high temperatures, low blood pressure and high heart-rate) and these are side effects of t-cell therapy.
The greater the number of tumour cells, the greater the release of cytokines because the immune response needs to be greater. Therefore, a correlation has been found in the severity of CRS with the numbers of cancer cells in a patient – in some instances, this is life threatening.
- Cost of treatment
The length of time required for enriching, genomic editing and activation of CAR-T t-cells has significantly decreased over time, but this has required significant investment in technologies that increase the speed of the process. The process also requires significant man-power to develop each personalised treatment for each patient. Therefore, the $475,000 price tag on Kymriah treatment, for example, is reflective of the investment into CAR-T therapies over the years, rather than a single figure for the actual process of editing one patient’s t-cells – estimated to be around $15,000 (or £11,500).
CAR-T therapy is the first gene therapy to be approved for use in the USA and it looks as though approval will soon come in Europe too. It offers an additional treatment option for certain lymphomas and leukaemias that have failed to respond to current first line treatments and the quality and extension added to life of a patient cannot be downplayed.
Whether these factors are enough to demonstrate cost-effective use of NHS resources is something that no one can yet be sure of. It’s safe to say that once these treatments are approved for use in Europe, we will be sharing our input and working with NICE to determine the answer!