PARIS, 7 August 2004 — Scientists say they have unearthed important new clues in the search for a treatment for skin cancer, which in some cases can be fatal and which is affecting more and more people, especially in developed countries.
After carrying out a series of experiments on mice a team of scientists in the United States has arrived at what they call a “simple technology” to cure a metastatic disease, or a cancer that spreads throughout the body.
The results of their study will appear in the September issue of Nature.
During chemotherapy — one of the standard ways of treating cancer — healthy cells are destroyed along with cancerous cells.
Researchers led by Richard Vile at the Mayo Foundation in Rochester, in the US state of Minnesota, have attempted to turn this feared secondary effect to their advantage by better stimulating the immune system so that it attacks the tumor.
“Deliberate destruction of normal tissue can be exploited to generate immunity against a malignant disease originating from that tissue,” say researchers in a report already posted on the Internet at http: www.nature.com.
Provoking an immune response — the role of a vaccine — assumes that cells responsible for defending the organism recognize the aggressor, or intruder in the case of a melanoma, and are prepared to fight it.
One of the principal obstacles has been to identify specific markers on cancerous cells — known as peptides or proteins — which can make it possible for lymphocytes, white corpuscles inside white blood cells, to recognize them.
But recent studies have shown that healthy melanocytes, the skin’s pigment-producing cells that make people tan, have similar markers that the immune system can train itself to recognize.
Those advances led to the idea, tested with success by Vile and his team on mice, of sacrificing normal cells to destroy melanomas without first having to identify those specific markers associated with the cancerous cells. In experiments a viral enzyme included in a vector was injected under the mice’s skin which converts an antiviral substance known as ganciclovir into a drug that can damage cellular DNA.
This led to an inflammatory reaction leading to the destruction of normal cells, and at a later stage, tumor cells. Repeated several times this type of treatment was able to completely destroy the tumor without causing any long-term auto-immune reaction to healthy tissue, the researchers say.
