Virus as medicine: Genetically engineered virus can cure cancer, scientist learn
The worldwide study, which was led by the Institute of Cancer Research in the UK and published in the Journal of Clinical Oncology, says that an artificially created virus called T-VEC can provide skin cancer patients with more efficacious treatment.
Clinical trials have been going on for more than three years in 64 centers across the US, UK, Canada and South Africa. If further studies are also successful, the new drug will be more widely available by next year, the scientists predict according to the Guardian.
T-VEC is a modified herpes virus which multiplies inside cancer cells until they burst open. After destroying the cancer cell, the virus gets into surrounding area and triggers a secondary immune reaction against the tumor.
Dr Hayley Frend, science information manager at Cancer Research UK, commented: “Using a virus to both kill cancer cells and nudge the immune system into attacking them is exciting. 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 virus is deprived of two key genes, which makes it impossible for it to replicate in healthy cells – so, normal cells detect and destroy T-VEC before it can cause damage. That means the virus is practically safe for patients.
During the research more than 400 patients were injected with the drug every two weeks for up to 18 months. They had flu-like symptoms after the first few injections, but on the whole such treatment has much milder side effects than other therapies.
The scientists appreciate the results of the study as highly positive. Patients with stage three and early stage four melanoma lived on average for 41 months after T-VEC-therapy, while other people with the same stage of skin cancer lived for only 21.5 months. Ten percent of the patients had “complete remission” with no detectable symptoms of cancer – regarded as a cure if the patient is still cancer-free between three and five years after diagnosis.
“This is the big promise of this treatment. It’s the first time a virotherapy has been shown to be successful in a phase 3 trial,” Kevin Harrington, professor of biological cancer therapies at the Institute of Cancer Research London said, as cited by the Guardian.
“The results are especially encouraging, because all the patients had inoperable, relapsed or metastatic melanoma with no conventional treatment options available to them. They had disease that ranged from dozens to hundreds of deposits of melanoma on a limb all the way to patients where cancer had spread to the lungs and liver,” he added.
The scientists noticed one more interesting feature – the immune system after the T-VEC therapy becomes capable of detecting and attacking cancer throughout the body. As a result, even secondary tumors not infected also shrank or even disappeared. “It’s like an unmasking of the cancer,” explained Mr Harrington. “The patient’s immune system wakes up and attacks the cancer cells wherever they are in the body.”
If the success of virotherapy as a remedy against skin cancer is proved, it will give hope that the same methods will be effective in the treatment of other types of cancer.
The idea of curing cancer with viruses isn’t new – it emerged in the early 20th century. In 1949, 21 patients with Hodgkin’s lymphoma were injected with viral hepatitis. Seven people had temporary remission while one died and 13 others contracted hepatitis. Today, virotherapy is much safer due to genetic engineering, which allows for creating less dangerous versions of natural viruses.
“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,” the Telegraph quoted Professor Paul Workman, CEO of the Institute of Cancer Research, London.
According to the “World Cancer Report 2014” published by the World Health Organization, 232,000 people across the world had skin cancer and 55,000 died of it in 2012. About 88 percent of patients live for more than five years after the detection of the disease, but life expectancy for aggressive forms of skin cancer with the illness spreading to other organs is much lower.