Metformin Blocks Cancer Cell Nutrients

Metformin shown to alter metabolic pathways of cancer cells.

A recent study shows that metformin may change the mechanisms of cancer cells by inhibiting their source of nutrients, making it an effective treatment option.

Researchers previously found that patients with diabetes who were diagnosed with head and neck cancer were more likely to have better outcomes, compared with patients without diabetes.

To determine why patients taking metformin for diabetes had superior outcomes, the authors of a study published by The Laryngoscope examined cancer cells before and after treatment with the drug.

"This study is the first step in showing how metformin acts on head-and-neck tumors, and we are excited that it could eventually offer patients a method of improving their outcomes with few side effects," said study senior author Ubaldo Martinez-Outschoorn, MD.

The investigators discovered that metformin is able to alter the pathways cancer cells depend on for fuel. It also alters the environment around the cancer cells that support growth and metastasis, according to the study. These findings are significant because if cancer cells are weakened due to a loss of nutrients, they may be vulnerable to attack from other treatments.

"Because tumors need a lot of energy to grow quickly, throwing a wrench in their energy-production pathway makes this kind of cancer more susceptible to standard therapies," said study first author Joseph Curry, MD.

Included in the study were 39 patients treated with metformin in doses half of what is normal for patients with diabetes. Their tumor cells were examined before and after treatment with metformin for evidence of apoptosis, and changes in metabolic pathways.

The researchers found that patients treated with metformin had increased amounts of tumor cell apoptosis, and a deterioration of cancer-supporting fibroblasts., This means that cells are incapable of assisting cancer cells with growth and metastasis, according to the study.

Metformin is known to be well-tolerated and less toxic, compared with other cancer drugs. Few patients included in the study experienced side effects, and were typically low-grade events, such as upset stomach. No patients were observed to have serious adverse events.

"This study demonstrates that metformin has effects on head-and-neck cancers, at safe doses, that are at or lower than what is given to diabetic patients and that it changes head-and-neck tumor biology in a way that likely makes the cancer easier to kill," said co-author Madalina Tuluc, MD, PhD. "Metformin disrupts the cancer's most efficient method of generating fuel for its growth and shuts off the cancer's support system."

Additional studies have found similar results when metformin is used in combination treating patients with cancer.

The researchers plan to conduct additional studies to further confirm that metformin may be beneficial for patients with head and neck cancers.

"The next step would be to test these doses of metformin in phase II clinical trials with a greater number of patients," Dr Martinez-Outschoorn concluded.