Diabetes drug may kill cancer stem cells, study says

Results from a new study suggest low doses of the diabetes drug metformin may effectively destroy pancreatic cancer stem cells, reducing the risk of tumor growth or recurrence.

Metformin has previously shown promise in reducing breast cancer risk, after researchers found women who took the drug were 25 percent less likely to develop breast cancer during their lifetimes than women who did not.

This study, conducted in mice, is the first to suggest metformin may actually target the root of certain cancers – the tumor-initiating stem cells.

“We didn’t have any clue regarding the effects of metformin on pancreatic stem cancer cells,” study researcher Dr. Christopher Heeschen, professor for experimental medicine at the Spanish National Cancer Research Centre in Madrid, Spain, told FoxNews.com.  “It’s been implied in past studies of pancreatic cancer that patients who use metformin show better outcomes, but there have been no randomized trials yet.”

When metformin was combined with a standard chemotherapy to treat pancreatic cancer, the drugs were able to eradicate both cancer stem cells and the differentiated cells that made up the tumor.

“Novel strategies for treating pancreatic cancer have to be multi-modal,” Heeschen explained.  “Right now, metformin is used as a second phase treatment, but I could also envision it as a first phase treatment – but it has to be in combination with chemotherapy.  I don’t think the drug alone could wipe out the primary tumor, which is crucial.”

In the study, it appeared that metformin merely arrested cancer cell growth in existing tumors, rather than destroying them.

“Metformin targets the root of cancer, which has more of an effect on preventing cancer relapse,” Heeschen said.

According to Heeschen, researchers are not yet certain as to why metformin appears to have cancer stem cell-killing properties, but “from a pragmatic point of view, you see this striking response with a well-established drug that’s safe – I think it’s reasonable to move forward with clinical trials,” he said.

One clinical trial is already in the recruitment phase, and Heeschen predicted results of the trial would be available by the end of the year.

“Based on that data and our data, we can move forward and design future prospective trials,” he said.

The study was presented Tuesday at a conference hosted by the American Association for Cancer Research.