Dr Aneurin Kennerly, University of Sheffield
When it comes to targeting cancer in the body, one of the biggest challenges is delivering drugs directly to tumours, killing cancer cells efficiently while avoiding damage to healthy tissue which causes side effects. Now, a new study reveals a novel way to guide immune cells loaded with cancer-killing viruses into tumours using the power of an MRI, or magnetic resonance imaging, scanner. Aneurin Kennerly told Kat Arney how the new technique came about...
Aneurin - There are viruses that have been designed that can actively attack tumour cells. One of the biggest problems is getting them to the tumour itself. Obviously, our bodies are going to fight viruses and if you just inject them, the body will naturally fight the virus away. But what you can do is you can carry them inside a macrophage or a white blood cell that is inherent to your body anyway and so, will that pass freely and itís kind of a Trojan horse therapy itís been known as before. The problem with this is that if you just do this naturally about Ė so say, I inject a few million white blood cells that have our cancer treatment in them, only 5 per cent of them will ever reach a tumour site.
The initial ideas here were that you would magnetise the white blood cells and then if you place the magnet, a small external magnet over the tumour then the white blood cells, as they float around the body, the iron within them would be attracted to the little external magnet and therefore, they would stay in the region of the tumour. The only problem with this technique is that itís only useful for kind of superficial tumours, that is on the skin, and they can really be easily removable with surgery anyway. What happens if the tumours are deeper within the body? And thatís where the MRI system comes in. Itís a giant magnet itself and we can actually localise the field using the imaging gradients so we can start to target tumours deep within the body.
Kat - So, how do you make these cancer killing cells magnetic?
Aneurin - So, we place into the white blood cells, tiny little iron particles that are already used as MR contrast agents around the world and they just contain tiny little iron particles and as we all know, iron is very magnetic. So, thatís the beauty of the research that weíve been doing. The actual magnets exists in every hospital in the world. They're used every day in diagnosis. Itís exactly the same hardware. We did not change the hardware in any respect. So, this can just be an application of that hardware in a new way.
Kat - I guess, marrying this kind of tumour targeting treatment in an MRI scanner, you can see what's going on at the same time as well.
Aneurin - Yeah, thatís the real beauty of the technique. As well as targeting the therapy to the tumour, we can look at the development of the tumour over time in a traditional way that we would use MRI anyway. So, letís say our patient has to sit in the MRI scanner for an extra 10 minutes while their therapy is induced and thatís the real benefit of the technique that MRI is already being used to assess whether tumours are in your body. If we can find them, if the radiologist can find them, then he will know where to target to.
Kat - How have you tested it so far?
Aneurin - At the moment, the current study is concerning prostate cancer. Prostate cancer was induced within our mouse model and we also looked at the metastases into the lungs so weíve directed the therapy towards the lungs in some cases and looked at whether it reduced the metastases of the prostate cancer.
Kat - How well does it actually work?
Aneurin - In the current study, we treated the animals with one section of magnetic resonance targeting and it lasted between 30 minutes and 1 hour for each animal. We noticed a marked reduction in tumour size over a 21-day period.
Kat - Where are we with this research? Is it the kind of thing that we could see in hospitals very soon?
Aneurin - So, the study weíve done at the moment is a pre-clinical study. It was done in mice. A mouse is much smaller than a human. So, the forces that we can generate in our pre-clinical system, we may be able to generate in a human system and that would need more testing. We would also need to test kind of how long we need to do the targeting for and how often. So, probably about 3 to 5 years letís say, before we see clinical application of this and clinical testing.
Pretty slick idea, but the primary MRI field surely makes it more difficult to drive the projectiles towards the target. A neater trick would be to use x-ray imaging and MRI-type gradient fields with no primary polarising field, to produce a 3-D gradient peaked at the target.
How can we improve effectiveness of cancer treatments?