As medical advancements continue to revolutionise patient care and treatments, NHS patients with Lymphoma have for the first time been given a pioneering treatment that genetically reprograms their immune system to fight cancer.
The therapy, called CAR-T is a ‘living drug’, and is tailor-made for each patient using their body’s own cells. In order to learn more about this new therapy, we must first understand that T-cells are a type of lymphocyte which develop in the thymus gland, and they play a central role in immune response – and T-cells can be distinguished from other lymphocytes by the presence of a T-cell receptor on the cell surface.
With this in mind, we ascertain that CAR-T cells are chimeric antigen receptor T-cells, are T-cells which have been genetically engineered to produce an artificial T-cell receptor for use in immunotherapy treatments. These CAR-T cells are therefore reception proteins that have been engineered to give T-cells the new ability to target a specific protein.
So ground-breaking is this treatment, doctors at King’s College Hospital in London said that some patients were being completely cured in a way that had never been seen before.
So, how does the treatment work?
The fact that CAR-T has to be developed for each individual patient means that it has now been hailed the pinnacle of personalised medicine, and that’s why we’re interested to know more about how this treatment works.
First of all, parts of the immune system, specifically the T-cells we mentioned earlier, are removed from the patient’s blood – where they are then frozen in liquid nitrogen and send to laboratories in the USA. There the white blood cells (T-cells) will be genetically reprogrammed so that they seek out and destroy cancer, instead of killing bacteria and viruses, as this is their main purpose.
This ‘reprogramming’ takes place when a harmless virus is used to deliver genes into the T-cells, which then modifies them to recognise and target cancer cells – and at this point they have now become CAR-T cells. These modified cells will then be duplicated in the lab, and eventually injected back into the patient.
And while it sounds like a long and complicated process, the whole manufacturing process takes just one month – vital when treating patients with blood cancer, who need treatment as soon as possible. Crucially, as this is a ‘living drug’, the cancer-killing T-cells remain in the body for a long time, and they continue to grow and work inside the patient.
Who does this treatment benefit?
One of the first NHS patients to be treated was diagnosed with large B-cell lymphoma, a type of blood cancer, in 2015, with initial symptoms of a stiff and swollen neck. Two rounds of chemotherapy initially controlled the cancer, but unfortunately each time it returned and by the end of 2018 the patient was given less than two years to live.
The patient started the CAR-T therapy in February 2019, and subsequent follow-up scans suggest that the therapy is working – and while it’s too soon to know whether the therapy has been completely successful, it does bring some degree of hope and optimism to patients with the same and similar types of blood cancer.
How effective is it?
Because this is a new therapy, very long-term data is still lacking, however, clinical trials have shown that 40% of patients had all signs of their otherwise untreatable, terminal lymphoma eliminated from their body 15 months after treatment. While this may be the new ‘miracle treatment’, it doesn’t come without its side effects – short-term neurotoxicity where the brain and nerves are affected can lead to confusion, difficulty speaking and even a loss of consciousness.
In fact, the patient we mentioned earlier spent five days in intensive care after the treatment that they cannot remember at all. That being said, their brain function is now back to normal and they are certain that the side effects suffered were worth it.
Will this treatment work for other cancers?
This treatment has shown the most promise in blood cancers, including types or lymphoma and leukaemia; at this stage, solid cancers – those that form tumours, like lung cancer or melanoma – have been more challenging.
It’s thought that the treatment is most successful is due to the fact that there is more acceptable ‘collateral damage’. That is to say, CAR-T cells target proteins that stick out from the surface of a cancerous cell, and cancerous B-cells have a protein called CD19 on the outside, but, so do healthy B-cells. Therefore, CAR-T therapies which target CD19 are wiping out both healthy and cancerous cells.
This is seen to be an acceptable amount of collateral damage, as the rest of the immune system is still there, and further drugs can help to plug the gap. Unfortunately, however, the same cannot be said for other cancers; essentially, you cannot destroy the lungs to kill lung cancer, or destroy the skin to kill melanoma.
But, the good news is that more precise targets for these therapies are being developed, and are entering clinical trials, signalling hope for the future of cancer treatments and optimism for cancer suffers everywhere.