Cancer Drugs Offer New Hope in Fight Against Alzheimer’s Disease
As Alzheimer’s disease cases continue to rise globally, a surprising new avenue for treatment is emerging: cancer drugs. Researchers are finding that oncology medications, originally designed to combat tumors, show promise in targeting key pathways involved in Alzheimer’s, offering a potential breakthrough in a field long considered stagnant.
The Growing Alzheimer’s Crisis
Alzheimer’s disease, a progressive neurodegenerative disorder, is the most common cause of dementia, accounting for 60-70% of all dementia cases. The scale of the problem is immense and growing. According to the Alzheimer’s Association, projections estimate that over 7 million Americans will be living with Alzheimer’s dementia by 2025. Globally, the situation is even more stark, with an estimated one person developing dementia every three seconds, and the total number of people living with the condition expected to reach 78 million by 2030.
For decades, Alzheimer’s has been a therapeutic dead end, with limited treatment options and no cure in sight. While two drugs, Leqembi and Kisunla, have recently been approved by the FDA to slow the progression of early Alzheimer’s, their effectiveness is currently limited. Many pharmaceutical companies have scaled back or halted Alzheimer’s drug development programs after unsuccessful trials, leading researchers to explore alternative strategies.
Repurposing Cancer Drugs: A Novel Approach
Researchers at the University of California, San Francisco (UCSF), have taken a different tack, screening a database of over 1,300 drugs – including antipsychotics and chemotherapy drugs – to identify candidates for repurposing in Alzheimer’s treatment. Their study, published in the journal Cell, highlighted two cancer drugs that demonstrated significant potential in reducing Alzheimer’s risk when tested on mice.
These drugs, one typically used for breast cancer and the other for colon and lung cancer, appeared to slow or even reverse Alzheimer’s symptoms in the animal models. The research team found that Alzheimer’s causes significant changes in gene expression in the brain, disrupting brain function and contributing to memory loss. From their initial database, fewer than 90 drugs successfully reversed markers related to Alzheimer’s in human brain cells, narrowing the field to five particularly effective candidates, ultimately focusing on the two FDA-approved cancer drugs for mouse testing.
How Do They Work? Targeting Key Pathways
The findings revealed that letrozole, the breast cancer drug, appeared to influence gene expression in nerve cells, while irinotecan, used for colon and lung cancer, affected glial cells, which provide support for the nervous system. Alzheimer’s disease is known to damage nerve cells and trigger an overgrowth of glial cells, leading to brain inflammation.
Interestingly, previous studies have indicated a correlation between reduced Alzheimer’s risk and the use of these drugs in other contexts. Breast cancer patients treated with letrozole have shown a lower incidence of developing Alzheimer’s, and colorectal cancer survivors treated with irinotecan have also exhibited a decreased risk, bolstering the excitement surrounding these new findings.
Promising Results, But Challenges Remain
Researchers have observed encouraging results in mice, with the combination of the two cancer drugs reversing brain degeneration and improving memory in animals exhibiting signs of Alzheimer’s. However, they acknowledge that success in animal models does not guarantee the same outcome in humans. A clinical trial with Alzheimer’s patients is planned to further investigate the potential of this treatment approach.
“Developing a new drug can take hundreds of millions, or even billions, of dollars, and on average takes more than 10 years,” noted Dr. Yadong Huang, a co-author of the study and a neurology professor at UCSF, as reported by NBC News. “For this repurposed drug, usually, it just takes two or three years, and then you can go to the clinical trial, and the cost is much, much lower.” Despite this efficiency, Dr. Huang cautioned, “We still haven’t generated or produced any very effective drugs that can really slow down dramatically the cognitive decline.”
The exact mechanisms by which these cancer drugs might benefit Alzheimer’s patients remain unclear. One theory suggests that letrozole reduces estrogen production, which in turn regulates many genes. Another proposes that irinotecan reduces brain inflammation by inhibiting the proliferation of glial cells.
Dr. Melanie McReynolds, a biochemistry assistant professor at Pennsylvania State University, who was not involved in the study, highlighted another potential angle. Her research suggests that other cancer drugs can help Alzheimer’s by regulating glucose metabolism, which is crucial for cellular energy production. “With aging, with stress, with diseases, that line of communication is disrupted,” she explained, believing the drug combination could reverse metabolic decline, “the secret for contributing to better outcomes with Alzheimer’s.”
The Future of Alzheimer’s Treatment
Cancer drug repurposing represents a transformative chapter in Alzheimer’s treatment, allowing researchers to leverage existing data on drug toxicity and pharmacokinetics, potentially accelerating human testing and reducing development costs. However, potential side effects must be carefully considered. Letrozole can cause hot flashes, and irinotecan may lead to severe diarrhea. “These drugs have huge side effects, so you need to always balance and figure out whether those types of side effects would be amenable to somebody with Alzheimer’s,” cautioned one expert. “It’s not that it’s a slam dunk.”
While the path forward is not without its challenges, the discovery that cancer drugs may hold the key to treating Alzheimer’s disease offers a beacon of hope for the millions affected by this devastating condition.
