Italian researchers have developed what they call a 'Trojan horse' that poisons tumours from within.
The Milan scientists genetically tweaked blood cells that usually favour tumours to produce interferon, a natural anti-viral drug that has been used against kidney, skin and blood cancer.
Until now, because of the impossibility of delivering it into the tumour, interferon has had to be used at high doses - so toxic that therapy is often stopped.
But the Trojan horse will carry the substance to the heart of the cancer, allowing ''mini-doses'' to be steadily supplied, said the team at Milan's prestigious San Raffaelle research hospital.
''With this system,'' researchers said, ''the drug is released in a continuous way and only inside the tumour itself, without the toxic effects that have frequently been observed with conventional methods''.
The team led by Luigi Naldini used gene therapy to modify so-called TEM cells, which normally contribute to tumour growth.
Once modified, they produced interferon.
''Thanks to gene therapy the TEM cells reached the tumour and released interferon in it,'' said researcher Michele De Palma.
''This natural drug slowed and in some cases stopped the development of the tumour, as well as restricting the spread of metastasis''.
So far the interferon-based Trojan horse has only been used on guinea pigs but in future, researchers say, it could be used in humans in combination with chemotherapy and other treatments.
The San Raffaele team's work is published in the current online edition of the journal Stem Cell.
