David Potter, MD, PhD, is going after the baddest, meanest breast cancers he can find.

“We want to go beyond treating easy-to-kill cancer cells,” Potter says. “We want to kill the toughest of the tough.”

Thanks to improving therapies and earlier detection, survival rates for breast cancer have never been higher—but certain subsets of the disease are resistant to treatment and remain as deadly as ever.

To tackle these extra-tough tumors, Potter and his team are using biguanides, a class of drugs originally designed to fight diabetes but recently shown to work against tumors as well. These drugs attack tumor cells and activate the immune system’s ability to fight the tumor.

Potter likens immune T cells that fight cancer to firefighters saving a home from an automotive fire in a garage.

“Imagine that the resistant tumor is like a burning car with a powerful engine consuming oxygen and producing toxic fumes,” he says. “The biguanides are like a hand that turns off the car’s engine. By activating our ‘firefighters,’ in this case the body’s immune system, we’re able to smash our way into that garage, and get the biguanides in to shut off the ignition, and then have the ‘firefighters’ drag that car out of the garage to save the occupants of the house.”

Potter and his collaborators are assessing this treatment in animal models and hope to translate it to human clinical trials in the near future with additional philanthropic support.

Gifts from donors like the Taylor Family Foundation and the Randy Shaver Cancer Research and Community Fund have been integral in his team’s research progress thus far.

“None of this would have been possible without their support,” Potter says.