For decades, there was no treatment for Alzheimer’s disease. Once it took hold, there was no slowing it down.

Now, it appears, the age of Alzheimer’s treatments has begun in earnest.

A new drug, donanemab, in a clinical trial was found to clear amyloid plaques from the brain in participants, and slow cognitive decline by about a third.

In the clinical trial, 47 percent of participants, who were in the early stages of Alzheimer’s, remained stable in their day to day lives over the subsequent year. This compared with 29 percent who took a placebo.

The trial

Indianapolis drug company Eli Lilly hasn’t yet published the full findings of the trial.

The 1182 trial participants were in the early stage of the disease, and their brains had deposits of two Alzheimer’s proteins – beta-amyloid and intermediate levels of tau, a protein linked with disease progression and brain cell death.

The participants were still living their regular day-to-day lives, holding conversations and driving.

Donanemab was given as a monthly infusion until the distinctive plaques in the brain were gone.

Results

At 12 months into the trial, half the participants showed no sign of beta-amyloid plaques.

The BBC reports that the pace of cognitive decline slowed by about 29 per cent overall – and by 35 per cent “in a set of patients researchers thought more likely to respond”.

On the downside, side effects include brain swelling and brain bleeding.

Serious brain swelling affected 1.6 per cent of the participants, and killed two participants, and a third patient died after an incident of serious brain swelling.

Theory gains ground

This is the second Alzheimer’s drug to slow cognitive decline in Alzheimer’s patients by clearing beta-amyloid plaques, the proteins that gunk up the brain cells.

What makes this so exciting is that the beta-amyloid theory (of causing Alzheimer’s by gumming up the brain) has been just that – a theory.

Now it’s starting to firm up.

Dr Ronald Petersen, an Alzheimer’s researcher at Mayo Clinic, told the ABC that Eli Lilly’s trial “is the third to show removing amyloid from the brain slows progression of the disease, which could put to rest some lingering doubts about the benefits of drugs in the class and the amyloid-lowering theory”.

The earlier drug

In November, we reported that lecanemab – a monoclonal antibody developed by Tokyo pharmaceutical company Eisai, and biotechnology firm Biogen in Cambridge, Massachusetts – had reduced cognitive and functional decline by 27 per cent in a Phase III clinical trial.

It had similar side effects to the new drug.

About 20 per cent of participants who received lecanemab showed abnormalities on their brain scans that indicated swelling or a small amount of bleeding, “although less than 3 per cent of those in the treatment group experienced symptoms of these side effects”.

Now it appears that Eli Lilly, the company that developed donanemab, also a monoclonal antibody, has improved on that.

The rate of brain swelling is lower with donanemab, and the level of slowing cognitive decline is better.

The BBC reports that the pace of cognitive decline slowed by about 29 per cent overall – and by 35 per cent “in a set of patients researchers thought more likely to respond”.

This is building hope and expectation that an even better monoclonal antibody will come along sooner rather than later.

Eli Lilly reportedly hopes to have donanemab prescribed in hospitals soon.

Alzheimer’s researchers somewhat ecstatic

Dr Cath Mummery is clinical lead for the cognitive-disorders clinic at the UK’s National Hospital for Neurology and Neurosurgery.

She told the BBC: “The decades-long battle to find treatments that change Alzheimer’s disease is changing.

“We are now entering the time of disease modification, where we might realistically hope to treat and maintain someone with Alzheimer’s disease, with long-term disease management rather than palliative and supportive care.”

Dr Liz Coulthard, from the University of Bristol, told the BBC there were “significant side effects” and a lack of long-term data but the drug could “help people live well with Alzheimer’s for longer”.

Dr Richard Oakley, the associate director of research at the Alzheimer’s Society in the UK, said: “This could be the beginning of the end of Alzheimer’s disease.”