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2002 11 05 Dienstag dyree(e) in K
 | Cancer vaccine shuts off blood supply |
| 11:50 05 November 02 |
| NewScientist.com news service |
| The latest cancer vaccine has an unexpected target - it triggers an immune system attack on growing blood vessels rather than tumours. This cuts off the blood supply cancers need to grow. |
| Cancer cells have evaded previous vaccines by constantly mutating, but the new vaccine avoids this by targeting the healthy blood vessel cells associated with the tumours. And the same vaccine could be given to everyone, instead of having to be tailored to target specific cancers. |
| Trials of drugs that block the growth of tumour blood vessels have not been very successful, and the drug has to be taken continuously. But one dose of the vaccine might provide long-term protection, the latest experiments suggest. |
| To design the vaccine, Ralph Reisfeld, at the Scripps Research Institute in La Jolla, California, and his colleagues added the gene for a protein called FLK-1, which is found on cells in new blood vessels, to Salmonella bacteria. The bacteria were then fed to mice. |
| When the animals were injected with skin and lung cancer cells, the resulting tumours grew to only a quarter of the size of those in unvaccinated mice. "We saw tumours vanish or we could not detect them anymore, and we saw tumours that took longer to grow," says Niethammer. |
| Half a lifetime |
| The researchers also vaccinated mice with colon cancer that had already spread to the lungs. All treated mice survived, despite some lung damage, but the untreated mice all died. |
| Tumours often escape the effect of anti-cancer drugs if they are sheltered by a mass of scar tissue or the blood-brain barrier. But Reisfeld says that the immune system's killer T cells can reach growing blood vessels no matter where the tumour is. |
| The vaccine also gives long- term protection. It was just as effective in mice that were injected with cancer cells 10 months after immunisation. "The beautiful thing about T cells is that they have a memory," says Reisfeld. "And 10 months in a mouse is almost half its lifetime." |
| The only side effect the researchers detected was that wounds took longer to heal. But cancer vaccine expert Jeffrey Schlom of the National Cancer Institute near Washington DC warns that careful safety studies will be needed before the vaccine is given to people. |
| Journal reference: Nature Medicine (DOI:10.1038/nm794) |
| Anil Ananthaswamy |
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