Scientists have reported promising results from a trial using a genetically engineered virus to treat skin cancer (melanoma). The virus, which normally causes cold sores, was genetically modified and harmless to normal cells but when injected into tumours it replicates and releases substances to help fight the cancer. Trial results published in the Journal of Clinical Oncology show the therapy could lengthen survival by years – but only for some melanoma patients. The treatment is still in the testing phases and not yet available.

The latest study is the largest ever trial of an anti-cancer virus and involved 436 patients from 64 centres in the US, the UK, Canada and South Africa who had inoperable malignant melanoma. There is a lot of interest in using viruses as a cancer treatment as they can infect tumour cells and help to kill them directly and also they can stimulate the immune system to fight the cancer cells. As viral treatments can be used to attack cells directly it is hoped that such treatments will be more targeted with less side effects.

The new viral treatment, known as T-vec, showed promise in the trial extending the survival of people with advanced stage melanoma. Further studies are now expected, including identifying which patients respond best to treatment and why some people do not seem to respond as well to the viral therapy. Scientists hope this trial represents positive proof of concept steps in the development of a potentially effective line of treatment for melanoma and that viral therapies can be applied to other cancers.

Melanoma, the most serious form of skin cancer, is the sixth most common cancer in the UK – it kills more than 2,000 people in Britain each year. Damage to the skin by the sun’s harmful UV rays increases your risk of developing this cancer.

Rachel Kayani