T cells are important fighters against disease. T cell Credit: NIAID/NIH (public domain), via Wikimedia Commons
The news comes from a conference in Washington DC in the US. And while the science is extremely exciting, the media’s response has jumped the gun a little.
At the conference, researchers from the Fred Hutchinson Cancer Research Center in Seattle described how they’d taken specialised immune cells from patients with certain blood cancers, and re-engineered the cells in the lab to attack and kill cancer cells when injected back into the patient’s body. You can read all about the science behind this particular approach – called Chimaeric Antigen Receptor T-cells, or CAR T-cells – in this blog post.
The researchers also summarised the results of several small, early-stage clinical trials, where they’d begun seeing some impressive responses in some very sick patients. But these trial results are yet to be published in a scientific journal, so are still to be scrutinised by experts in the field.
Nevertheless, harnessing the power of the body’s own immune cells, and focussing their attack on cancer in this way, is a really promising area of research, and something our own researchers are working hard to perfect. And several immunotherapy drugs are already being used on the NHS, showing some incredible results in a certain groups of patients – as this article shows.
But as is often the case with media stories heralding potential cures for cancer, we also need to add a note of balance.
‘Extraordinary’ responses… but not cures
The early stage trials in today’s reports involved patients with different types of blood cancer – including acute lymphoblastic leukaemia, chronic lymphocyte leukaemia and non-Hodgkin lymphoma. While these are often very treatable forms of cancer, the patients on these trials had diseases that had become resistant to all other treatments.
Many media reports focused on the patients with acute lymphoblastic leukaemia, more than nine in 10 of whom are reported to have entered remission following the immune cell therapy.
The researchers are also reported to have seen similarly impressive responses in around half of patients with the other blood cancers too.
These are indeed truly impressive results.
But these responses – where patients see their symptoms disappear – don’t necessarily mean a patient has been cured. And without a scientific paper to back up the reports, we don’t yet have the full details on these responses rates – notably exactly how they were measured.
So once the data have been scrutinised and published, there will need to be longer-term follow-up before it’s clear if these patients get lasting benefits.
Lead researcher Professor Stanley Riddell has been widely quoted as calling the results ‘extraordinary’. But he has also made it clear that the results are in patients where all other treatments have failed. “The response is not always durable, some of these patients do relapse,” he said.
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And this raises an important point. The patients recruited to these studies had very advanced cancers. “Most of the patients in our trial would be projected to have two to five months to live,” said Riddell. But for most people with these cancers, there are highly effective treatments available.
So it’s important to view these latest findings as part of a bigger picture. Only with further research will we truly understand the role this type of immune cell therapy might play in treating these cancers.
And it’s also important to focus on where this type of approach could be used to target other cancers in desperate need of new treatments. As we said above, the results reported today focus on blood cancers, which – for a range of reasons we discussed in this post – are likely to be much more responsive to this type of immune-boosting treatment.
So it’s vital to find ways to adapt this approach to treat so-called ‘solid’ tumours – a much bigger challenge, but one that our scientists, along with others around the world, are already looking at closely.
While many reports made a big deal of the benefits for patients who did respond to the immune cell therapy, most early reports missed some important details about some of the risks.
The immune system is a powerful weapon, and this type of approach unleashes its full force within the body. And because of these powerful responses, patients offered this type of treatment as part of a trial can occasionally see very serious side effects.
In these latest trials, reports have emerged that seven of the 35 patients on one trial experienced severe side effects that left them in intensive care, with two dying as a result. Clearly, there’s a lot more to learn about how the body reacts to these powerful treatments.
There’s also very little known about this treatment’s long-term effects in those who benefitted.
All this just serves to illustrate how much more there is to learn about this type of therapy.
Many of today’s reports were also quick to mention the potential of this treatment to offer an immune ‘memory’ of cancer.
This is a tantalising prospect, as it’s possible that cancer-targeting immune cells might persist in the body, preventing cancer coming back. And the team behind today’s headlines are exploring this by using T-cells which they hope will survive in the body for many years.
This was thanks to another study, also discussed at the Washington meeting, where Italian scientists showed that transplanted ‘memory’ T-cells could persist in the body for more than a decade. While this wasn’t ‘cancer’ research, it was looking to improve the safety of stem cell transplants for patients with a variety of diseases. But the findings were adapted and used to inform the US trials discussed above.
So it appears that the truly ‘new’ element of this latest approach was using these ‘memory’ T-cells to treat the patient’s cancer. The hope would be that, in the case of a patient who responds, the immune memory cells would ensure the cancer would be killed again if it returned.
This could be an exciting development, although it’s still too early to tell how long the patients on this trial will retain these reengineered immune cells. And with some patients already relapsing, it’s clear there is a lot more to learn.
Why talk about prevention?
But some media outlets took this ‘long-lasting immune response’ a step too far, claiming immune memory could be turned into a ‘vaccine’ that could ‘prevent cancer’.
Unleashing these cells on a patient’s cancer is very different to developing a surveillance system that would spot and kill cancer cells in their earliest stages in healthy people as some of today’s headlines suggested.
But while a cancer-preventing vaccine is likely a way off, it’s absolutely something to work towards – and it’s an idea that forms a key part of our Grand Challenge to transform cancer prevention and treatment in the future.
But to be clear, the research discussed in the media today didn’t aim to develop this sort of preventative approach.
Part of a growing arsenal
Immunotherapy will play a huge part in cancer treatment in the future. That’s something we know for sure.
But whether it will come in the form of drugs that release the ‘brakes’ on the immune system, cell therapies like those in the news today, or something completely new, working out exactly how it will be used, and in which patients, is an urgent challenge for researchers,
What we do know is that it will need to find a place among other, successful treatments that are already available. And today’s reports are a great example of this – offering a way to treat patients for whom current approaches don’t work. So we’re eagerly awaiting the full publication of the US team’s findings.
But we also need to focus on immunotherapies that target other cancers in desperate need of new treatments.
Hopefully then, with larger, longer-term studies, we will be able to talk about immunotherapy truly offering lasting cures for patients with cancer.