Scientists have discovered that combining two previously approved cancer drugs effectively treats Alzheimer’s disease. The one-two punch may be able to reverse the devastation of this disease that affects 7 million people in the U.S., causing a dramatic decline in cognition, learning and memory.

Researchers at the University of California San Francisco found that two cancer drugs approved by the Food and Drug Administration (FDA) were able to restore cells affected by Alzheimer’s disease to normal in mouse models.  A drug used to treat breast cancer, letrozole, in conjunction with irinotecan, used to treat colon and lung cancer, improved memory and reduced brain damage in mice with Alzheimer’s.

According to Study Finds, when the researchers investigated 1.4 million real-world cases of people who had been treated with these drugs, they found that the incidence of Alzheimer’s disease was lower than normal. It appears that the combination therapy is effective in reversing the disruption of genes associated with Alzheimer’s disease in the neurons and glia, the two main cell types in the nervous system.

Using brain cells from deceased donors with and without Alzheimer’s disease, the researchers were eventually able to narrow down approved drugs that were effective in reversing the gene expression in these cells, according to a press release from UCSF.

They tested the drugs on mouse models that had been genetically programmed to develop Alzheimer’s disease. The combination of the two cancer drugs reversed multiple aspects of Alzheimer’s in the mice by undoing the gene expression signatures in the neurons and glia that emerged as the disease progressed. It reduced both the formation of toxic clumps of proteins as well as brain degeneration. The drug therapy also restored memory in mice, according to an established memory test.

When the researchers examined human medical records, they found that in breast cancer patients who received letrozole, the rate of Alzheimer’s diagnosis was 53% lower than matched controls. For colorectal cancer patients treated with irinotecan, the rate was 80% lower.

Both drugs can cross the blood-brain barrier, a crucial requirement for treating brain diseases, and the doses used in the mouse study were within human-relevant therapeutic ranges based on prior dosing studies, says Study Finds.

Dr. Yadong Huang, co-senior author of the study, says he hopes the research, published in the journal Cell, will advance to a clinical trial so the team can directly test the combination therapy in Alzheimer’s patients.

“If completely independent data sources, such as single-cell expression data and clinical records, guide us to the same pathways and the same drugs, and then resolve Alzheimer’s in a genetic model, then maybe we’re onto something,” said co-senior author Marina Sirota. “We’re hopeful this can be swiftly translated into a real solution for millions of patients with Alzheimer’s.”