A surprising new study has found that a breast cancer drug known as Tamoxifen could have the ability to turbo-charge white blood cells and kill superbugs.

The study, published by UC San Diego in the journal Nature Communications, has found that Tamoxifen can enable the white blood cells to find and destroy antibiotic-resistant bacteria, often referred to as superbugs because of how difficult they are to kill, according to a San Diego Union-Tribune report.

One of the diseases it could potentially fight is methicillin-resistant staphylococcus aureus, or MRSA, which recently gained headlines after an NFL player got it and now faces potentially losing a foot due to it. MRSA kills about 11,000 Americans each year, based on Centers for Disease Control and Prevention data.

The research team used Tamoxifen in mice that had been infected with MRSA, something that would have typically killed them. They found that survival rates jumped by a third in mice that had received the drug. It also worked well against two other superbugs, according to the report.

But the problem is that so far its effects have only been proven on mice, and that it may still be a long time before it’s approved for use on humans. Still, it’s an important development that will likely lead to further research and could potentially result in an effective new drug to battle MRSA and other deadly ailments.

Dr. Victor Nizet, who is the senior author of the paper, said he hopes this research will lead to clinical trials in patients who have severe infections.

Tamoxifen is already used as a breast cancer drug in hundreds of thousands of women, so it’s already been proven to be safe for human use. Still, that doesn’t necessarily mean it will be immediately adapted to this new treatment. Although Tamoxifen can be used in certain cases in humans, it is not known what the side effects would be if used in these situations.