Drug trial fails in Alzheimer’s study

An experimental Alzheimer’s drug failed to slow cognitive decline in a two-year clinical trial, but the results may still help scientists understand how the disease progresses.

Trial finds no benefit from ceperognastat

Researchers testing ceperognastat, also called LY3372689, reported no meaningful improvement in patients with mild cognitive impairment and raised Tau protein levels. The drug, developed by Eli Lilly, was compared against a placebo in a double-blind, randomized controlled trial involving 327 participants across 72 medical centers in five countries.

Patients, aged 60 to 85, had baseline scores of 22–30 on the Mini-Mental State Examination (MMSE) or a Clinical Dementia Rating (CDR) global score of 0.5 or 1. All showed evidence of raised Tau through blood tests and PET imaging. The trial ran from September 2021 to July 2025.

After two years, cognitive decline rates were statistically identical between the placebo group and those receiving either 0.75 mg or 3 mg of ceperognastat. In fact, participants on the higher dose showed signs of accelerated deterioration, though the difference wasn’t large enough to draw firm conclusions.

What the failure reveals about Alzheimer’s

Ceperognastat was designed to target enzymes that modify Tau, a protein long suspected of damaging neurons in Alzheimer’s. Some researchers believe Tau aggregates directly harm brain cells, while others see it primarily as a biomarker—a sign that damage is already underway.

The trial didn’t support the drug’s effectiveness, but it did produce unexpected findings. PET scans showed that patients on ceperognastat accumulated fewer Tau aggregates in the lateral temporal lobes over the study period. They also lost less brain volume, particularly in the hippocampus, and had lower levels of phosphorylated Tau in their blood.

Those results don’t prove Tau is irrelevant. Instead, they suggest that blocking a specific enzyme—O-linked N-acetylglucosaminidase—may not be the right approach. If reducing Tau phosphorylation or aggregates doesn’t protect cognitive function, researchers might shift focus to other mechanisms.

This could mean Tau plays a secondary role, or that the damage occurs earlier in the disease process than previously thought. Either way, the findings help narrow the list of potential targets for future treatments.

The study, published in JAMA, doesn’t rule out Tau entirely. But it does suggest that therapies aimed at this pathway may need a different strategy—or that scientists should look elsewhere for answers.

For now, the search continues. The trial’s failure, while disappointing, offers a clearer path forward by eliminating one hypothesis and redirecting resources toward more promising avenues.