T-cell immunotherapy successes are raising hopes of a breakthrough in cancer treatment. Dr Lim ZiYi at Parkway Cancer Centre explains.
T-cell immunotherapy, which involves genetically modifying the body’s immune system to fight cancer, is showing impressive results in clinical trials, with high percentages of patients experiencing complete remission.
How does this new therapy work?
For many years, mainstay of cancer treatment has involved surgery, radiotherapy or chemotherapy. But in the last few years, there has been a lot of interest in a new field called immunotherapy or how to use your body’s own immune system to fight cancer.
The results from several new studies are very exciting.
They look at a particular type of immune cell in our bodies called the T-cell which is important in fighting cancer. T-cells have long been recognised for their ability to home in and destroy cancer cells in our body. However, in patients with very aggressive or resistant cancers, the number of T-cells is often low or is not effective. Scientists have now found ways to genetically modify the T-cells to supercharge them. They are extremely potent and can target cancer cells directly and are able to kill them with far greater potency.
Are there other ways to boost the T-cells’ ability to fight cancer?
There are ways to stimulate the immune system and the T-cells using certain immunotherapy drugs or chemotherapy drugs.
However, this new form of cell therapy is a bespoke and targeted way to harness our body’s immune system and to direct them specifically against cancer cells.
How are cancer-targeting T-cells made?
The scientists extracted T-cells from cancer patients, then, genetically modified them. They basically insert a particular gene in these T-cells which allows these cells to recognise markers on the cancer cells which they are targeting at.
These modified T-cells are like smart bullets – the T-cells have a receptor which allows them to home in on the cancer cells. Importantly, they are not just hitting the target, but once they bind to the cancer cells, they stimulate more T-cells around them so you get a very big cluster of T-cells which try to get rid of the cancer.
What kind of results did we see in the trial patients?
The researchers primarily focused on patients with blood cancers (lymphoma and leukaemia) because from the early results, these were the cancers which were most responsive to this form of therapy.
The response rates have been around 80 to 90 per cent and these have not been brief responses but sustained responses.
We have seen heavily treated patients with huge tumours go into complete remission. The longest lasting patient has been in remission for two and a half years. It has got us all quite excited although it is only a very small number of patients studied so far – less than 100.
Are there downsides to this treatment?
A fair number – around 10 to 15 per cent of patients in the study – developed severe side effects.
One of the reasons is that these cells are so potent that when they kill the cancer cells, they release massive amounts of chemicals into the body which cause patients to become very ill. Some patients had to be admitted into ICU for organ support.
Is this therapy likely to go mainstream in the next few years?
There is still quite a way to go before this treatment can become mainstream.
It is a form of designer immunotherapy – where you are super boosting a patient’s immune system specific for the type of cancer he or she experiences. It takes a lot of effort to develop one therapy for one patient. We have to get each patient’s cells and produce it in a special laboratory.
We also have to find better ways of managing the side effects before we can introduce it to a larger group of patients. Realistically, we are looking at two to three years and even then, it will still be a treatment for a selected group of patients and not as frontline therapy.
Are we going to be able to see this approach applied to other types of cancer?
That would be the next big stage. If this proof of concept works, we want to see if we can apply it to other more common cancers. There are some studies under way looking at the more common cancers like pancreatic, ovarian and liver cancers.
At this stage, the most promising results are in the blood cancers. In terms of the broader field of immunotherapy, there is a lot of work to see if we can manipulate other cells to boost the immune system or fight cancer.
Is immunotherapy a better approach than traditional forms of therapy?
It would be ideal if we could create T-cell therapy that we could get off the shelves and does not cause side effects. The idea to harness your own immune system rather than use drug therapy to fight cancer is a very attractive idea.
However, chemotherapy and radiotherapy will remain important in fighting certain types of cancer.
Different methods are still needed to fight cancer because cancer will always find ways to get around it. This is an exciting breakthrough therapy, and it is very encouraging for our patients that we will have more weapons at our disposal to fight cancer.
This article is based on Dr Lim ZiYi’s radio interview with 938LIVE’s health talk-show, Body & Soul, in Singapore.
Tags: blood cancer, cancer latest breakthrough, common side effects of cancer treatment, immunotherapy