The study aimed to show that Alzheimer’s disease could be stopped if treatment began before symptoms emerged. The participants were the best candidates that scientists could find: still healthy, but with a rare genetic mutation that guaranteed they would develop dementia.
For five years, on average, the volunteers received monthly infusions or injections of one of two experimental drugs, along with annual blood tests, brain scans, spinal taps and cognitive tests.
Now, the verdict is in: The drugs did nothing to slow or stop cognitive decline in these subjects, dashing the hopes of scientists.
Dr. Randall Bateman, a neurologist at Washington University in St. Louis and principal investigator of the study, said he was “shocked” when he first saw the data: “It was really crushing.”
The results are a deep disappointment, scientists said — but not a knockout punch. The drugs did not work, but the problems may be fixable: perhaps the doses were too low, or they should have been given to patients much younger.
Few experts want to give up on the hypothesis that amyloid plaques in the brain are intimately involved in Alzheimer’s disease.
The study was small, with only 194 participants: 52 taking a drug called gantenerumab, made by Roche, and an equal number trying solanezumab, made by Eli Lilly. Most of the subjects had no symptoms; a few were experiencing very mild early symptoms. About 40 family members served as a comparison group, and received no medication.
The volunteers carried gene mutations that cause an overproduction of amyloid, which accumulates in hard plaques in the brain. That is enough to always cause Alzheimer’s disease. The experimental drugs attacked amyloid, and scientists like Bateman had hoped they would prevent cognitive decline.
The participants in DIAN-TU were younger than the typical Alzheimer’s patients and did not yet have other brain abnormalities, like mini strokes. Success in this trial, it was hoped, would show that defeating Alzheimer’s was possible.
“This was a bold experiment driven by a deep unmet medical need in these patients,” said Dr. Daniel Skovronsky, chief scientific officer at Eli Lilly.
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