Potential for radiotherapy and VTP multimodality therapy for prostate cancer

Each year in the UK around 48,500 men are diagnosed with prostate cancer, and 11,900 die from this malignancy. The most common radical treatments for prostate cancer are surgical removal of the prostate gland (prostatectomy), or radiotherapy (usually combined with hormone treatment).

However, there is a need to improve the overall patient outcomes from radical treatment, as many cases of high-risk prostate cancer recur. Moreover, there is an unmet clinical need to reduce radical treatment side effects.

Vascular targeted photodynamic therapy (VTP) is a novel minimally invasive precision surgery technique that has been developed to focally treat prostate cancer. VTP destroys the vasculature supply of blood to the tumour, thereby providing tumour control.

To date, VTP has been investigated in clinical trials as a monotherapy for low-volume, low-risk prostate cancer. Whilst VTP has been combined with other treatments such as hormone therapy in pre-clinical models, to date it has not been investigated alongside external beam radiotherapy to assess the effects of combined treatment on prostate cancer tumour control.

A recent study from Richard Bryant and Freddie Hamdy of the Nuffield Department of Surgical Sciences, alongside collaborators in the Institute of Biomedical Engineering & Department of Oncology, and collaborators from the Weizmann Institute of Science (Israel) and the National Cancer Institute (National Institutes of Health, USA), has investigated the impact of combining VTP with external beam radiotherapy treatment, and the potential improvement to treatment outcomes.

In a recent publication in the British Journal of Cancer, the team used a multi-modality treatment approach to test the sequential combination of fractionated radiotherapy and VTP – which have previously not been used together.

They found that, whilst fractionated radiotherapy or VTP alone can help delay tumour growth, combination therapy using fractionated radiotherapy followed by VTP suppressed tumour growth to a greater extent than either treatment alone. Radiotherapy induced changes to the blood vessels within the tumour, which may be a contributing factor to the increased effectiveness of subsequent VTP as part of combination therapy. Ongoing studies are now investigating the immunological effects of the combined treatment.

This is the first time that VTP has been evaluated in combination with external beam radiotherapy treatment, either for prostate cancer or any other solid-organ tumour. This pre-clinical study provides the proof-of-concept necessary to go on and test this multi-modality approach in first-in-man early phase clinical trials. Following future testing of safety and efficacy in patients, this combined radiotherapy and VTP approach could help to redefine best practice for treating certain prostate cancer patients in a more effective way.

About the study

This study was a collaboration between Richard Bryant (Nuffield Department of Surgical Sciences), Freddie Hamdy (Nuffield Department of Surgical Sciences), Ruth Muschel (Department of Oncology) and Avigdor Scherz (The Weizmann Institute of Science, Israel). It was funded by a Cancer Research UK & Royal College of Surgeons of England Clinician Scientist Fellowship (reference C39297/A22748) and by a research grant from The Urology Foundation.