By blocking production of a protein which drives the development of tumours, researchers were able to eliminate the tumours without any evidence of adverse sideeffects.
The study found that the treatment was effective even after several rounds of therapy suggesting that the mice did not become resistant to it – a major problem for cancer doctors.
Scientists now hope to adapt the treatment into a form that is suitable and safe for use on humans so that its effectiveness can be tested in clinical trials.
Dr Laura Soucek of the Vall d’Hebron Institute of Oncology in Barcelona, who led the study, said: “We’re so excited about reaching this turning point and I am quite certain that it will change the course of cancer therapy, despite there being a long road ahead.”
The therapy targeted a protein known as Myc, which plays an important role in our cells but can lead to uncontrolled cell growth and the onset of cancer if it is overproduced by the body.
Mice were given an antibiotic in their drinking water which activated a mutant gene known as Omomyc, and this in turn blocked the production of Myc.
Previous studies had already established this procedure for inhibiting Myc, but there were concerns it could have serious sideeffects.
In the new experiment, described in the Genes and Developmentjournal, Mice with up to 200 lung tumours were given the therapy for four weeks, followed by four-week rest periods for more than a year.
After the first treatment all the mice’s tumours disappeared, but 63 per cent then relapsed. Following the second treatment, only 11 per cent of the original tumours resurfaced. After eight therapy cycles, only two tumours could be identified.
Dr Soucek said: “The most important finding was that there were no signs of resistance to treatment. This is one of the biggest disadvantages of many anticancer therapies: the disease develops resistance and can return even more aggressively.
“The fact that the results are maintained over time, that there is no tumour relapse and no resistance, suggests that Myc-targeted therapy may offer an unprecedented way forward.”
Francesco Pezzella, Professor of Tumour Pathology at Oxford University, who was not involved in the study, said it was a promising proof of concept but cautioned that the approach was not directly applicable to humans.
“It would be a good idea in humans to try and find a way to block that gene,” he said. “But the way they have done it is not possible in humans because it requires a modified gene which is inserted inside the [mice’s] cells.
“It gives the green light for pharmaceutical studies to try to find a compound that can block this gene…but whether it would be possible to block it in humans is still completely unknown.”