A new drug, donanemab, slows down the course of Alzheimer’s disease slightly. The results were presented in a grand manner on Monday at an international Alzheimer’s congress in Amsterdam. It is the third drug in a short time that scientists seem to be able to influence the process of that disease.
But this too is primarily a scientific breakthrough. The effect is limited, the drug is very expensive, and the side effects are considerable. This gives little hope for patients. The accompanying study appeared in the medical-scientific journal on Monday JAMA.
The drug, donanemab from manufacturer Eli Lilly, is an antibody against beta-amyloid, a protein that forms insoluble clots in the brains of people with Alzheimer’s dementia.
More than 1,700 elderly people with early Alzheimer’s participated in the study. Half received an infusion of the drug every month for a maximum of eighteen months, the other half received a placebo. People whose beta-amyloid levels had reached a healthy level were then continued to receive placebo. More than half were there within a year.
After a year and a half, the treated group had deteriorated less on a score sheet that measures thinking ability and daily functioning. The patients early in the disease phase benefited most from the drug. They lost an average of 6 points with the treatment, the placebo group more than 9 points (the maximum score is 18). Almost half of them (47 percent) had not deteriorated in the first year. But even in the group of people who received placebo, almost a third did not deteriorate further.
Side effects
The drug seems slightly more effective than the previous two, but participants also had more side effects. More than a third developed brain swelling or microbleeds, and in 1 in 60 people these were very serious. Three people died from the treatment.
In the United States, two similar drugs (from the companies Biogen and Esai) have been approved by the US drug authority FDA since 2021. Controversy surrounds the first drug, aducanumab, while the second drug, lecanemab, was fully approved in June. The first drug has been rejected in Europe, the European medicine agency EMA is still examining the second drug. For the new drug, donanemab, manufacturer Eli Lilly submitted the application for approval to the FDA on Monday. It is expected to make a decision before the end of this year.
“These results clearly indicate that we have entered a new era with Alzheimer’s research,” says neurologist Niels Prins. He is director of the Brain Research Center, which conducts clinical research on behalf of pharmaceutical companies and where 22 of Eli Lilly’s test subjects were treated with donanemab. “After lecanemab, this is the second drug that convincingly shows that a patient benefits from clearing beta-amyloid,” says Prins.
By-product
Whether this really addresses the cause of the memory loss is a matter of debate among scientists. Some suspect that beta-amyloid is just a by-product, because the amyloid plaques are sometimes also found in the brains of elderly people who do not have dementia symptoms.
Neurologists Pim van Gool (Amsterdam UMC) and Edo Richard (Radboudumc and Amsterdam UMC) pointed out in this newspaper on Thursday that despite treatment, the disease continues to proliferate. They find the effect of the drugs far too scant, the use far too expensive, and the side effects too great.
Read also: Thinking differently about Alzheimer’s: is the protein clot the cause or is there more to it?