In a groundbreaking Phase III trial, researchers demonstrated the first-ever viral treatment for cancer.
A genetically engineered herpes virus proved to halt the progression of skin cancer in its tracks, the Institute of Cancer Research reported. The new treatment method works by attacking and killing cancer cells and prompting the immune system to destroy tumors.
"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," said trial leader Professor Kevin Harrington, Professor of Biological Cancer Therapies at the ICR and Honorary Consultant at The Royal Marsden.
Researchers gave 436 patients with aggressive, inoperable malignant melanoma either an injection of the viral therapy, dubbed Talimogene Laherparepvec (T-VEC), or a control immunotherapy. About 16 percent of the group treated with T-VEC exhibited a treatment response of more than six months, compared with only 2.1 percent of the control group. Some of the patients in the T-VEC group had responses that lasted for as long as three years, which is a milestone that is often considered "cured" by immunotherapy standards.
The researchers noted responses were most dramatic in patients in patients with less advanced cancer and who had not yet received treatment, suggesting T-VEC is a good candidate for a first-line melanoma treatment. Patients with stage III and early stage IV melanoma who received the new viral treatment lived an average of 41 months, compared with an average survival rate of 21.5 months in patients who received immunotherapy.
T-VEC is a modified form of herpes simplex virus type-1, it multiplies inside cancer cells and causes them to explode. The version used in the treatment was genetically engineered to produce the molecule GM-CSF, which drives the immune system to destroy tumors.
"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,"said professor Paul Workman, Chief Executive of the ICR. "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."
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