A new Immunotherapy treatment for advanced prostate cancer can halt and even shrink tumours, a recent trial has shown.

Almost half of the patients saw their tumour shrink after taking the drug, and the majority experienced a significant reduction in their PSA levels. The researchers were also pleased to note that most only experienced very mild side effects.

The trial tested the new VIR-5500 drug in 58 patients with advanced prostate cancer that has stopped responding to other treatments. The aim of the trial was to determine the safety of the drug and find the best dose to prescribe. The drug uses a 'cloaking device' to ensure it does not activate until reaching the tumour, which helps prevent side-effects and allows it to stay in the blood stream for longer, meaning fewer doses may need to be given.

This type of treatment has previously led to severe side effects in prostate cancer patients, but thanks to the cloaking device, 88 per cent of them did not experience the adverse effects which are usually seen.

The phase I trial involved 8 sites around the world and was led by Professor Johann de Bono at The Institute of Cancer Research, London and The Royal Marsden NHS Foundation Trust.

Prof. de Bono said that this trial raises hope of a cure for people whose cancer has already spread. 'in the not-too-distant future'.