About 268,000 women in the United States will be diagnosed with breast cancer this year, and 41,000 will die from the disease. Now, a study by a Louisiana researcher suggests a drug to prevent breast cancer or stop its progression may already exist.
Suresh Alahari, a professor of biochemistry and genetics at the LSU Health New Orleans School of Medicine, published research last week indicating that metformin, a drug typically prescribed to diabetes patients, might also keep cancerous tumors from forming.
The study used genetically altered mice to test whether metformin could raise levels of a key enzyme linked to tumor prevention.
The mice were intentionally made deficient in a protein called nischarin, which in turn made an enzyme known as AMPK inactive. Mice that didn't receive metformin developed tumors all over their bodies. The mice that were given metformin, which activates AMPK, saw a much smaller incidence of tumor development than mice that were genetically normal.
“That tells us this gene is protecting animals from getting tumors,” said Alahari, a breast cancer researcher.
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The study adds to a growing body of research on metformin, which regulates blood sugar, and has been called a possible “miracle drug” with the potential to help patients suffering from a raft of diseases.
Off-label, metformin is regularly prescribed for polycystic ovarian syndrome and prediabetes, though the Food and Drug Administration has not approved its use for those purposes. It's also increasingly being taken by a group known as "superagers" who are on a quest to retard the aging process and extend their years of healthy living.
A search on clinicaltrials.gov, the federal website that tracks ongoing clinical trials, shows it’s being studied as a possible aid against dementia, frailty, cardiovascular disease, autoimmune diseases, various cancers and aging.
Researchers are starting to address how one drug, a chemical version of a plant that for centuries was used to treat frequent urination, could address so many different diseases.
“The short answer to that very important question is that nobody knows,” said Gerardo Ferbeyre, a biochemistry professor at the University of Montreal. “We can say for sure that it acts in mitochondria,” he said, referring to the part of a cell that generates energy.
One way it may work, he said, is by inhibiting inflammation. The other way that has been proposed is through activating AMPK, the enzyme studied at LSU.
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Metformin has proved in animal studies to be able to prevent cancers, said Ferbeyre. “It’s promising. All of the animal models are excellent,” he said.
In humans, the drug has mainly been tested in large studies that track how diabetes patients who were prescribed metformin fared against people with the disease who took other drugs to treat their condition. In those patients, cancer risk was significantly lower for those taking metformin.
“If you look at epidemiological studies, you find that with metformin there is a reduction in cancer risk somewhere between 30 and 40%,” said Dr. Kishore Gadde, the medical director of clinical services at the LSU-affiliated Pennington Biomedical Research Center.
Gadde has studied metformin’s effect on obesity and longevity. He was not part of Alahari’s breast cancer study, but he called the data “compelling.” Still, he said it’s too soon to start taking metformin for diseases people don’t yet have. The drug has minimal side effects, though it very rarely causes a reaction known as lactic acidosis.
“Let’s say someone was found to have polyps on a colonoscopy,” said Gadde. “With polyps, there’s an increased risk of colon cancer. It’s something to consider in those instances, but at this point we don’t have strong evidence to make a recommendation.”
In the next few years, more evidence will trickle out of studies on how metformin treats or prevents cancer. The good news: Metformin has been approved for use in the U.S. since 1994 and in France since the 1950s, which means it will not have to go through rigorous safety testing.
But that same fact makes it difficult to fund studies of metformin through big pharmaceutical companies because there is not enough money to be made off of it.
“Metformin is very cheap,” said Ferbeyre. “It’s got to be government that will pay for a big clinical trial.”
For Alahari, the next step is to implant human breast cancer tissue in mice with and without the nischarin protein that activates AMPK. But results from that are at least five years away, with human trials even further down the line.
