Realizing the radiobiological impact of protons and high-LET particles in head and neck cancer and glioblastoma models

Project Summary Radiotherapy is still one of the most effective cancer treatments used to treatment ~50 % of all human cancers, and particularly solid tumours of the head and neck and brain. However, acute and long term adverse side effects of radiotherapy are still common, and some tumours are also resistant to the therapeutic effects of the radiation. The increased use of precision particle radiotherapy, particularly proton beam therapy, enables the radiation dose to be delivered precisely to the tumour, which spares the surrounding normal tissues of any unwanted radiation dose and is therefore able to limit some of the adverse side effects. Furthermore, the ability to deliver radiation that causes extensive damage to the tumour tissues (so called “high-LET”) is also a significant advantage in effective radiotherapy. However despite this, there is still uncertainty regarding the biological effects of protons and high-LET radiation on both normal and tumour cells and tissues, and how the radiotherapy can be optimised for patient benefit. This proposal brings together world leading experts in radiation physics, biology and clinical oncology to reveal new knowledge of the biological impact of protons and high-LET radiation versus conventional (x- ray) radiotherapy, on cell models of head and neck and brain tumours. This will be performed on both 2- dimensional, but also 3-dimensional cell models of the tumours which are more similar to those observed in patients. We will thoroughly analyse the precise effect of protons and high-LET radiation at the molecular (DNA) level, and how this correlates with the impact on overall survival of the cells. We will also investigate the role of important factors such as low oxygen levels (hypoxia) which is important in driving resistance of solid tumours of the head and neck and brain to radiotherapy, but also the rate at which the radiotherapy is delivered (particularly high dose rates, so called “FLASH”), on the biology and survival of the tumour versus the normal cells. Additionally, we will identify the combination of specific drugs and inhibitors under the various conditions that are more effective in combination with protons and high-LET radiation in optimising tumour cell killing, whilst sparing the associated normal cells. In the long term, our research will contribute to the identification and development of more effective strategies using radiotherapy, including proton beam therapy, for tumours of the head and neck and brain that are particularly resistant to the radiation treatment. This will lead to an improvement in the patient response but also in overall survival following precision particle radiotherapy. 1