Nathan Luedtke and colleagues explain that the spread of melanoma and other forms of cancer beyond the original location -- a process called metastasis -- makes cancer such a serious disease. Photodynamic therapy (PDT), which involves administering a drug that kills cancer cells when exposed to light, already is available. But PDT works only on the main tumor and has other drawbacks. Luedtke's team set out to find an improved approach to PDT.

The scientists describe successful tests in laboratory mice of one compound they synthesized that not only killed melanoma cells, but also stopped them from metastasizing by blocking a key signal inside the tumor cells. The compound "provides the first example of a preclinical candidate possessing both of these properties," the scientists state.

The authors acknowledge funding from the Swiss National Science Foundation.