New way to target tumours

The main cause of death for cancer sufferers isn’t the original tumour - it’s caused when cells from the tumour break off and spread around the body. This process, known as metastasis, makes cancer much harder to treat. If you could pinpoint this process in the body, with a kind of biological red flag, you could gear treatment towards the tumours, without damaging the rest of the body. This sounds simple, but has proven almost impossible as different tumours behave in such different ways. But now - a team at the University of California Irvine may have found such a red flag, which- in mice at least - allowed for a targeted attack on multiple tumours. Georgia Mills spoke to Dr Justine Alford, senior science info officer at CRUK, who was not involved in the study, about the research...

Justine - Tumours are incredibly diverse, not just in one person, but across people with different cancer types. We know that they’ve got a huge amount of variety in the faulty genes that they have and also the molecules that they produce. So, in order to try and make medicine more personal, more targeted to try and reduce the side effects and not attack healthy cells, it’s really important to try and home in on features that are specific to the cancer itself. But that’s really tricky when cancers are so diverse and are producing so many different molecules and flags it can be become really tricky to try and home in on something and to try and find something that is found, not only in all the tumour cells in one person’s, but across different peoples’ cancer as well.

Georgia - What’s this new idea then to try and tackle this?

Justine - There are already some cells in the body which can naturally home in on a feature which is found around tumours. The surrounding around cells is called the matrix, and scientists have found that in some tumours the environment around the tumour becomes more rigid, it becomes stiffer, and that stiffness actually promotes the cancer and helps it spread and get worse around the body. There are some cells in our body which can naturally already detect this stiffness and then use that to then become a more specialised type of cell - these are called mesenchymal stem cells. These are kind of like a blank slate cell that don’t yet have their identity, and they can use this stiffness to work out where they are in the body and then how they should respond to these cues.

The scientists then use this knowledge to their advantage and they developed a new type of cell based on the mesenchymal stem cells, which not only specifically can pick up this stiffness, but also respond to it and then make a molecule which activates a chemotherapy drug. So they developed a really specific targeted system that only targets the tumour rather than giving the drug throughout the body which can cause more side effects.

Georgia - Right. So there’s this blank slate cell which recognise the environment that you find around tumours and then, when it finds this environment, it actually changes and can be engineered to change into something useful for fighting cancer?

Justine - Exactly. What they’ve done is really quite clever. They’ve tweaked these cells so that they make a molecule which chops up a pre-drug. The scientists will give a drug that needs to be modified to turn into a chemotherapy that then can kill the cancer cells, so it’s a two part system. The cells themselves produce this molecule and then the scientists can give the pre-drug, and then when that arrives at the tumour, this molecule that the cells are making will modify that molecule and then turn it into the chemotherapy drug which then directly attacks the tumor right at the site where it hurts.

Georgia - Have they tested this - does it work?

Justine - They’ve tested this so far in mice so it’s all early preclinical work but, so far, the results have been encouraging. They were looking at mice with breast cancer, and in these mice they found that these cells not only homed in specifically to the primary tumour, to the tumour in the breast, but they also homed in to the tumour that has spread to the lungs and it killed these tumour cells and caused them to shrink.

Georgia - So they’ve had promising results in these mice but how encouraging would you say this is, and how important is this in the grand scheme of things?

Justine - This process of spreading is called metastasis. Unfortunately, when that happens, it makes the tumour much more difficult to treat. At the moment we don’t have any treatments that can specifically target metastasis and that is a huge problem since cancer spread is responsible for the majority of cancer deaths. So we desperately do need to find new ways to target this and to stop it from happening. Whether or not this will actually translate into something useful in the clinic, we just don’t know.

It’s definitely promising and really encouraging, but at this stage it is very early and it is experimental so they will need to do lots more research. But the promising thing is that scientists have already used this kind of stem cell in clinical trials before, and they have shown to be safe in people. Obviously, that doesn’t necessarily mean that his particular type of cell that they’re using in this study will necessarily be safe and effective, but at least we do have some grounds for positivity there.