image credit: The Institute of Cancer Research/Vimeo
A landmark clinical trial, led by researchers from the Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust, has found that a genetically-engineered herpes virus, that often cause cold sores, can halt the progression of skin cancer. The scientists found that the virus kills cancer cells and sparks the immune system into action against tumours. Their findings were published in The Journal of Clinical Oncology.
The clinical trial involved randomising 436 patients with aggressive, inoperable malignant melanoma to receive either an injection of the viral therapy, called Talimongene Laherparepvec (or T-VEC), or a control immunotherapy.
16.3% of patients given T-Vec showed a durable response to treatment of more than six months, compared with only 2.1% of the control patients. Some patients had a response extending past three years, a mark oncologists often use as a proxy for cure in immunotherapy.
A crucial aspect of the trial was that responses to treatment were more pronounced in patients with less advanced cancers and those who had yet to receive any treatment, underlying the potential of T-VEC as a first-line treatment for metastatic melanoma which cannot be surgically removed.
T-VEC’s efficacy against cancer is being hailed by researchers, specifically citing its two-pronged attack on cancer cells by stimulating the immune system to attack the cancer cells while destroying the cells itself from within.
UK Trial Leader Professor Kevin Harrington, Professor of Biological Cancer Therapies at the ICR and Honorary Consultant at The Royal Marsden, said: “There is increasing excitement over the use of viral treatments like T-VEC for cancer, because they can launch a two-pronged attack on tumours – both killing cancer cells directly and marshalling the immune system against them. And because viral treatment can target cancer cells specifically, it tends to have fewer side-effects than traditional chemotherapy or some of the other new immunotherapies.
“Our study showed that T-VEC can deliver a significant, durable benefit for people with melanoma. It is encouraging that the treatment had such a clear benefit for patients with less advanced cancers – ongoing studies are evaluating if it can become a first-line treatment for more aggressive melanomas and advanced disease.”
Professor Paul Workman, Chief Executive of the ICR, said: “We may normally think of viruses as the enemies of mankind, but it’s their very ability to specifically infect and kill human cells that can make them such promising cancer treatments.
"In this case we are harnessing the ability of an engineered virus to kill cancer cells and stimulate an immune response. It’s exciting to see the potential of viral treatment realised in a Phase III trial, and there is hope that therapies like this could be even more effective when combined with targeted cancer drugs to achieve long term control and cure.”
Dr Hayley Frend, science information manager at Cancer Research UK, told the BBC: “Previous studies have shown T-VEC could benefit some people with advanced skin cancer, but this is the first study to prove an increase in survival. The next step will be to understand why only some patients respond to T-VEC, in order to help better identify which patients might benefit from it.”