Washington, Sept 15 (ANI): A popular diabetes drug called metformin has been found to be effective in fighting breast cancer.

The findings of the study from Harvard Medical School showed that metformin, along with conventional chemotherapy, shows promise for treating and delaying recurrence of breast cancer.

"We have found a compound selective for cancer stem cells," said senior author Kevin Struhl, the David Wesley Gaiser professor of biological chemistry and molecular pharmacology at HMS.

"What's different is that ours is a first-line diabetes drug," he added.

The drug seemed to work independently of its ability to improve insulin sensitivity and lower blood sugar and insulin levels, all of which are also associated with better breast cancer outcomes.

"There is a big desire to find drugs specific to cancer stem cells," said Struhl.

"The cancer stem cell hypothesis says you cannot cure cancer unless you also get rid of the cancer stem cells. From a purely practical point of view, this could be tested in humans. It's already used as a first-line diabetes drug," he added.

Lead researchers Heather Hirsch and Dimitrios Iliopoulos found that the combination of metformin and the cancer drug doxorubicin killed human cancer stem cells and non-stem cancer cells in culture.

In mice, pre-treatment with the diabetes drug prevented the otherwise dramatic ability of human breast cancer stem cells to form tumours.

In cases where tumours were allowed to take hold for 10 days, the dual therapy also reduced tumour mass more quickly and prevented relapse for longer than doxorubicin alone.

"This is an exciting study," said Jennifer Ligibel, a medical oncologist at Dana-Farber Cancer Institute and an HMS instructor in medicine, who was not involved in the study.

"There is a lot of interest in studying metformin in breast cancer, but so far we do not have direct evidence that metformin will improve outcomes in patients," Ligibel said. "That's what this trial is for."

The findings appear online in the journal Cancer Research. (ANI)