Dr Tree plans to conduct a clinical trial, called TRAP, for men whose cancer has just begun to grow after treatment with abiraterone or enzalutamide. At the moment, disease progression after hormone therapy is taken as a sign that the cancer has become resistant to the treatment. However, Dr Tree thinks that for some men, it may just be some tumours that are resistant and, if she treats those, the rest of the cancer will still respond to abiraterone or enzalutamide.
She will test this idea by recruiting men whose cancer is only growing in one or two sites. They will continue to receive abiraterone or enzalutamide, but the growing tumour will be hit with a precisely targeted form of radiotherapy called Stereotactic Body Radiotherapy (SBRT). This involves hitting the tumour with beams of radiation from different directions, so that while the cancer receives a high dose of radiotherapy, the surrounding tissues experience much lower doses, which reduces side effects.
While the men are at the hospital for their radiotherapy appointments, Dr Tree will also take blood samples from them. They’ll also have a special type of whole body MRI scan before their first treatment and 6 months after radiotherapy.
The MRIs will help them to see if they can predict who SBRT plus continuing hormone therapy is likely to work best for. They will use the blood samples as liquid biopsies; examining the tumour DNA circulating in the blood to see whether it contains any markers that suggest the cancer’s resistance to hormone therapy has changed after SBRT, but also to see if they can find markers to predict which men will benefit most from this type of treatment.
By the end of this grant, Dr Tree hopes to show that for some men, treating their metastases with targeted radiotherapy can extend the time that their cancer responds to hormone therapy. She also hopes that the MRI scans and liquid biopsies will have given them some insight into the mechanism of hormone resistance and cancer spread, and allowed them to predict who will respond best to this new type of treatment.
In the long term, Dr Tree plans to run further, larger scale clinical trials that, if successful, will provide the evidence needed to make SBRT alongside continuing hormone therapy standard of care for the men who will benefit most from it.
Reference - RIA16-ST2-006
Researcher - Dr Alison Tree
Institution – The Royal Marsden NHS Foundation Trust
Award - £574,415