In a significant development in the field of Alzheimer's treatment, Eli Lilly has announced that its drug, donanemab, has been shown to slow the disease by about a third. The drug works in the same way as lecanemab, which made headlines last year when it was shown to slow the disease. Both drugs are antibodies that are engineered to clear beta-amyloid, a sticky substance that builds up in the spaces between brain cells and forms plaques, one of the hallmarks of Alzheimer's. Eli Lilly's clinical trial involved 1,734 people in the early stages of Alzheimer's, and the drug was given as a monthly infusion until the plaques in the brain disappeared. The pace of the disease was slowed by about 29% overall, and by 35% in a set of patients who were thought to be more likely to respond.
However, the trial also revealed that brain swelling was a common side-effect in up to a third of patients. While it was mostly mild or asymptomatic, two deaths were directly attributed to the condition, and a third volunteer died after experiencing it. Despite the side-effects, Eli Lilly has said it will begin the process of having its drug approved for use in hospitals in the next few months.
Scientists have hailed the development of a second drug that targets amyloid in the brain as proof that they are on the right track after decades of setbacks. However, the drugs appear to work only in the earliest stages of the disease, before the brain is too damaged. Additionally, it would still take a revolution in how the disease is diagnosed to make a difference, as only 1-2% of people undergo either brain scans or spinal-fluid analysis to determine whether they have Alzheimer's or another form of dementia. The cost of the drugs would also be a factor, as lecanemab costs over £21,000 per person per year. Nevertheless, experts have said that we are now "on the cusp" of having drugs available, something that was recently considered "impossible."