Scientists use herpes virus to fight skin cancer
Scientists have discovered a new weapon in the fight against cancer, and it comes from an unlikely source: herpes. A re-engineered version of the cold-sore virus named talimogene laherparepvec (T-VEC) has been successfully used to treat patients, with a promising 25% of candidates responding positively.
How does it work?
Scientists at The Institute of Cancer Research in London used a method called virotherapy to treat patients. Effectively using one disease to fight another, the team created the T-VEC drug by modifying the original herpes virus to become a cancer-killing machine.
The team first worked on disabling the way Herpes Simplex 1 infects healthy cells. By removing proteins that it uses to infiltrate cells, scientists were able to ensure the virus targets only cancerous ones. Then, just like a normal virus, T-VEC multiplies inside cancerous cells, and bursts them open, causing the drug to spread and attack nearby cancer cells.
Second, the team also modified T-VEC to produce a GM-CSF molecule. Much like a call to arms for the body’s immune system, the GM-CSF molecule alerts antibodies to nearby tumours, making T-VEC and the patient’s own cells take the fight to cancer.
Professor Paul Workman, chief executive of The Institute of Cancer Research, told The Guardian: “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.”
Scientists injected the drug fortnightly into 436 patients with an inoperable melanoma, and found that 16.1% of patients were in remission after six months; a further 10% were in complete remission. The figures are even more impressive when you consider that many of the patients were suffering from inoperable, metastatic or relapsed cancers, meaning there were no traditional alternatives left.
Despite their prognoses, 136 stage-3 and -4 patients treated with T-VEC lived for an average of 41 months, compared to 21.5 months for the 66 who weren’t. During the trial, patients experienced flu-like symptoms that were much preferred to those usually associated with chemotherapy.
The experiment was conducted as part of T-VEC’s phase-three trial, in which its effectiveness as a treatment is measured. Phase three is also the final trial through which drugs pass before being distributed to the public.
Made by Amgen, T-VEC has already been submitted to the main regulatory bodies, and could be available to patients in the US and Europe as early as 2017.