At the Alzheimer’s Association International Conference in July, researchers from around the world—including physician-scientists from Cedars-Sinai—shared the latest findings from clinical trials testing potential treatments for Alzheimer’s disease.
While more than 90% of Alzheimer’s drug trials don’t deliver the hoped-for results, experts say those studies are still essential.
“Even trials that aren’t considered successful are incredibly important in shaping our scientific knowledge,” said Mitzi Gonzales, PhD, director of Translational Research at the Jona Goldrich Center for Alzheimer’s and Memory Disorders.
“Trials that show us one pathway isn’t working can push us in new directions.”
Gonzales recently led a study testing a drug called rapamycin, known in early laboratory research to extend lifespan and reduce age-related problems.
In animal studies, rapamycin appeared to lower levels of amyloid beta and tau—two proteins linked to Alzheimer’s disease. The hope was to see similar benefits in people.
Instead, the trial found that amyloid and tau levels actually increased in participants. While disappointing, the finding raised new scientific questions. “It has been helpful for pushing us in new directions,” Gonzales said, “including looking at whether it might be more effective in earlier-stage disease.”
Samples collected during these “unsuccessful” trials—such as blood and cerebrospinal fluid—can also lead to breakthroughs years later. Sarah Kremen, MD, who directs the Neurobehavior Program at Cedars-Sinai, points to the influential A4 study.
That trial tested the drug solanezumab in people with elevated amyloid levels but no symptoms. The drug failed to improve thinking or clear amyloid from the brain, but it broke new ground by being the first to study people at risk before symptoms began.
The data and samples from that trial helped scientists identify a biomarker called pTau217 as an early indicator of Alzheimer’s disease.
This marker is now part of the first FDA-approved blood test that can detect the buildup of amyloid plaques in the brain—one of the hallmark signs of Alzheimer’s.
Gonzales and Kremen emphasize that Alzheimer’s is a uniquely complex challenge. The disease likely has multiple causes, many of which begin affecting the brain years before any symptoms appear.
The brain itself is still far less understood than other organs, and the processes that drive neurodegeneration are intricate and varied.
“The brain is not as well understood as other organs, and the processes underlying neurodegenerative disease are complex,” Kremen said. “It will take time—and many more clinical trials—to unravel all the different mechanisms behind Alzheimer’s disease.”
For researchers, every trial—whether it succeeds or fails—adds another piece to the puzzle, bringing the medical community closer to understanding and eventually stopping this devastating disease.
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Source: KSR.
