Roche Holding AG Participation (SIX:ROG) reported that its Alzheimer’s disease treatment could not stem a slide in patients’ cognitive abilities with an early form of the illness.

On Monday, the Swiss pharma company reported that results from the Phase III trials of the medicine ‘gantenerumab’ could not meet their primary endpoint of slowing the clinical drop in patients with mild dementia due to Alzheimer’s.

The failure of the said drug deals a blow to the so-called amyloid hypothesis that the clearing of toxic cells is going to ease cognitive loss in people suffering from the disease.

Roche and competitors Japan’s Eisai (TYO:4523) and Eli Lilly and Company (NYSE:LLY), have been aiming to create a drug that harnesses this hypothesis, with a treatment set to generate billions of dollars in sales.

Alzheimer’s disease is a neurological disorder causing the brain to shrink in size and cells to die. It has impacted an estimated 55 million people globally as recently as 2020. There is currently no known cure.

Shares in Roche fell in early trading.