A new clinical trial from the UK brings exciting results as a modified strain of the herpes virus has been successfully used to treat skin cancer patients, with only minor side effects.
The trial run included 436 patients suffering from aggressive melanoma that signed up to be treated through virotherapy – the usage of genetically modified strains of viruses that attack specific pathogens or cells, such as malign cancer cells. Kevin Harrington, professor of biological cancer therapies at the Institute of Cancer Research London, who lead the research team, said: “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.”
Named Talimogene Laherparepvec (T-VEC), the drug was administered once every 14 days for up to 18 months, participants only showing flu-like side effects after the first few injections. One in four patients responded well to the treatment, 16% of them still being in remission six months later, compared to the 2% of the control group, treated using immunotherapy. 10% of those treated using the new drug had complete remission, showing no signs of cancer. During the trial, the T-VEC group patients survived an average of 41 months, while those in the control group survived an average of 21.5 months. These results are especially encouraging as some of the patients were in too severe condition to respond to conventional treatment :
“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,” said Harrington.
T-VEC works by taking away the virus’ ability to produce the protein that allows it to infect healthy cells. But malign cells produce the protein needed on their own, offering the virus the means to infect and thrive in cancerous tissue. As the herpes virus multiplies vigorously inside the cancer cells they burst open, spilling the virus into the surrounding area, triggering a secondary immune reaction against the tumour.
“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” said Professor Paul Workman, Chief Executive of The Institute of Cancer Research. And once the immune system gets the wake up call from T-VEC treatment, even secondary tumours that have not been infected by the virus have shrunk or disappeared completely. “It’s like an unmasking of the cancer,” said Harrington. “The patient’s immune system wakes up and attacks the cancer cells wherever they are in the body.”
The trial results are so promising that the research team hope to get it on the market by 2016. And successfully passing a phase 3 trial means that the pharmaceutical company Amgen only needs approval from the FDA and European Medicines Agency before they can make the treatment commercially available.