LONDON, England, Thursday May 28, 2015 – While we usually think of viruses as the enemy, a new genetically engineered virus based on the herpes virus has cured cancer patients in a scientific breakthrough that raises hopes of an end to chemotherapy.
The new therapy has far fewer side effects than conventional treatments, moreover, because it harnesses the body’s own immune system to destroy cancer cells.
A worldwide study, led by the Institute of Cancer Research in the UK, showed that the new treatment let some patients with skin cancer live longer than the benchmark three years used by many oncologists to define a cure.
The therapy, “T-VEC,” works by infecting and killing cancer cells while also spurring the immune system into action against tumours.
At present, most cancers are treated using invasive surgery, chemotherapy and/or radiotherapy, all of which have side effects and risk additional damage.
The breakthrough therapy has far fewer side effects and inflicts no damage on healthy tissue or cells.
Clinical trials have been conducted in 64 centres across the UK, US, Canada and South Africa for more than three years.
The results showed that 163 patients with stage three and early stage four melanoma who were treated with T-VEC lived for an average of 41 months, compared with an average survival of 21.5 months for 66 patients who were given the current best immunotherapy drugs.
The response was most pronounced in patients with less advanced cancers, which underscored the potential benefit as a first-line treatment for inoperable metastatic cancers.
A modified form of herpes virus, T-VEC multiplies inside cancer cells and bursts them from within. It has been genetically modified to produce a molecule called GM-CSF, which stimulates the immune system to attack and destroy tumours.
It has also been modified to remove two key genes, preventing it from replicating within healthy cells. Normal cells detect and destroy T-VEC before it can cause damage, but it replicates easily in cancer cells because their infection defences are compromised.
It is the first of a new wave of virus-based cancer drugs to show benefits in a major controlled phase III trial.
The trial was funded by Amgen, the manufacturer of T-VEC, and is published in the Journal of Clinical Oncology.
While the breakthrough came in skin cancer patients, scientists said it raises hopes that the same process could be used for other cancers.