Purpose: Malignant pleural mesothelioma is a cancer, caused by asbestos, which currently affects 2500 people in the UK each year. The main symptom is breathlessness caused by fluid building up in the space between the lung and the chest wall (pleural effusion). Treatment involves draining the fluid to allow the lung to re-expand (pleurodesis). However, sometimes tumour growth over the surface of the lung can prevent it from re-expanding. This ‘trapped’ lung results in fluid re-accumulation and repeated drainage which can lead to discomfort and multiple hospital visits.

One approach to dealing with ‘trapped’ lung in mesothelioma is to insert a thin tube (Indwelling Pleural Catheter – IPC) into the space around the lung. The tube can stay in place for a long time allowing patients to drain off fluid at home.

Another approach is a keyhole surgical operation (video-assisted thoracoscopic partial pleurectomy/decortication – VAT-PD) to remove as much tumour as possible from the lining of the lung to allow it to re-expand.

While both approaches are currently offered in clinical practice, it is not known which of the two is most effective at relieving breathlessness. The only way to find out is to conduct a research trial comparing the two. The Investigators plan to do this, but first of all need to carry out a small pilot study to collect information necessary to help plan the full study.

Purpose:The purpose of this study is to find out whether the combination of avelumab and SBRT is safe and what effect avelumab has on mesothelioma when given in combination with SBRT. In addition, a goal of this protocol is to study the effect of radiation therapy on the immune system. It is thought that radiation treatment may create a form of ‘vaccine’ against cancer inside the body and immunotherapy may improve this effect. The combination of radiation treatment and immunotherapy may be more effective against cancer than either radiation or immunotherapy alone.