Killing cancer stem cells halts melanoma in mice

By Carey Goldberg, Globe Staff

In a key first step from theory to possible help for cancer patients, Boston-based scientists report today that they have managed to beat back a deadly human skin cancer in mice by targeting and destroying stem cells in the tumors.

The findings on malignant melanoma add weight to the growing belief among scientists that many types of cancer recur after treatment because of small, resilient groups of stem cells that survive and start multiplying all over again.

The research, published in tomorrow's Nature, shows that attacking melanoma stem cells is enough to halt a tumor's growth, said Dr. Markus Frank of Children's Hospital Boston, the paper's senior author. It thus offers new hope that this strategy will also work in humans -- perhaps, researchers say, within a few years.

"If this works with melanoma, this may also work with other tumors that are notoriously difficult to treat" once they have spread, said Dr. George Murphy, an author on the paper and chief of dermatopathology at Brigham and Women's Hospital.

Scientists have been researching cancer stem cells for more than a decade, and the work has gathered momentum as stem cell populations have been discovered in cancers ranging from brain tumors to leukemia. Under a microscope, stem cells look like other cancer cells, but they can drive the growth of cancerous tumors in much the same way normal stem cells can regenerate the body's healthy tissues

The new paper is exciting and well-done, said Dr. Peter Dirks, a University of Toronto researcher on stem cells and brain tumors who was not involved in the work.

He cautioned, however, that this latest study, as well as others on cancer stem cells, are only preliminary, it remains to be seen how broadly applicable the results are. Also, much of the work still awaits replication by other labs, he said.

"It's relatively early stages," he said, though he understands why the whole idea of cancer stem cells has recently "hit prime time: Because if you could treat those cells, maybe we'd have more effective, more long-lasting, more definitive cures for cancer. This [new] study is definitely a step in that direction."