Breakthrough in the treatment of canine brain tumours
Bas van Nimwegen has spent years conducting research into the use of radioactive holmium particles (‘microspheres’) as a treatment for cancer. He does so in collaboration with Radboud ľϸӰ Medical Center (Radboudumc) and a large team of other external partners. Now, he is on the brink of a major breakthrough. This autumn, Van Nimwegen has begun trials of a minimally invasive therapy that involves using a camera-guided needle to inject holmium microspheres into the brain tumour, using CT and MRI scans to monitor the process. The technique will first be used on dogs, but hopefully one day on humans as well.
The problem with tumour cells in the brain is that they are surrounded by healthy nerve cells. This makes the tumour cells difficult to remove; in only few cases is it possible to remove them all. When you excise a tumour, there is a risk of damaging healthy brain tissue in the process, so surgery is not always an option. And since radiation therapy involves a risk of damaging healthy brain tissue as well, the size of the dose delivered to the tumour is limited. With the help of visualisation technologies (MRI and CT), and the resulting ability to calculate the dose of the radioactive microspheres injected into the tumour, it is now possible to treat brain tumours in highly targeted fashion.
Destroy from the inside
Van Nimwegen explains: ‘After we anaesthetise the animal, we conduct a CT or MRI scan. Once the scan has been made, we use a flexible, camera-guided needle to inject a very large radioactive dose locally – straight into the tumour – which preserves the surrounding tissue. We can repeat this until the scan shows that the microspheres have permeated all sections of the tumour. As the tumour gets “coloured-in” by the microspheres, as it were, we are able to watch this directly via the scan. The microspheres destroy the tumour from the inside out. The treatment takes about an hour. Generally, the animal is expected to experience few to no side effects, but will remain in the clinic for a few days. Because we administer such a large dose, we expect to see improvement fairly quickly. In certain cases, it is possible to repeat the treatment if needed.’
Successfully
The holmium technique has already been used successfully in recent years, such as for tumours in the head and neck. ‘We have injected around forty tumours with radioactive microspheres. The treatment proved effective in the majority of the animals. On average, the tumours shrank by 50-80 per cent and the patients retained normal use of the tongue and other involved body parts. With these results, we’ve demonstrated that it’s possible to perform repeated and controlled injections of holmium into a tumour,’ says Van Nimwegen.
With this new therapy, we can treat animal patients while also observing them as a model for applying the same treatment in human patients in the near future.
Humans and animals
The study is supported by a grant from the Netherlands Organisation for Scientific Research (NWO) and is multidisciplinary and strongly translational in nature. Van Nimwegen: ‘An important portion of the research involves veterinary patients, that is dogs with brain tumours. Their tumours and the resulting symptoms are similar to those seen in human patients. With this new therapy, we can treat animal patients while also observing them as a model for applying the same treatment in human patients in the near future.’
Consortium
The research project is being conducted by a consortium of the Faculty of Veterinary Medicine, the Radboud ľϸӰ Medical Center in Nijmegen, Delft ľϸӰ of Technology, the Neurosurgery department at UMC Utrecht and two companies, Quirem Medical and Elekta.
Wanted: dogs with brain tumours
In connection with this experimental treatment, Bas van Nimwegen is looking for dogs, and possibly cats, who have been diagnosed with a brain tumour. Dogs with a brain tumour are eligible for this study provided the prognosis without further treatment is uncertain to poor, no other appropriate treatment is possible, or if the owner takes a fully informed and conscious decision to pursue this experimental treatment in lieu of other treatment options. Patients can be referred to the ľϸӰ Clinic for Companion Animal Health at Utrecht ľϸӰ by their own veterinarian or a specialist or other clinic. If the patient is a suitable candidate for participation in this study, the majority of the costs will be reimbursed.
For information contact Bas van Nimwegen
Honours programme
In the final year of her Bachelor’s programme, student Tarifa Versteeg was selected for the Veterinary Medicine Honours programme. This Faculty-wide programme offers excellent students an opportunity to better orient themselves and gain additional skills in conducting scientific research. For her Honours thesis, she spent a year working on Van Nimwegen’s project. ‘I learned a tremendous amount from working with the various partners; it was a way for me to familiarise myself with the world outside of Veterinary Medicine,’ according to Tarifa.
Tarifa’s research focuses on the application of CT technology during the treatment. Tarifa: ‘The advantage to using a CT scanner is that it’s quick and easy for us to make a CT scan during the treatment itself. An MRI scan takes quite a bit more time. On top of that, MRI scanners create a strong magnetic field, which means you have to take that into account as well: the system with the flexible needle and all the other objects used in the treatment must be non-magnetic.’