Die European Medicines Authority EMA (external link) has given the EU the green light for Alzheimer’s therapy. It recommends approval of the antibody lecanemab for the treatment of mild cognitive impairment or mild dementia at an early stage of the disease. In Germany alone, around a million people are affected by Alzheimer’s.
Lecanemab fights causes of Alzheimer’s
Current Alzheimer’s therapies only treat symptoms of the disease, not causal processes in the brain. This is different with Lecanemab: The antibody is directed against amyloid deposits in the brain and is intended to slow down the progression of the disease.
The main measure of effectiveness was change in cognitive and functional symptoms at 18 months, measured using a 0 to 18 dementia rating scale. Patients treated with lecanemab had a slightly smaller increase in the value after 18 months on average (1.22 versus 1.75). This indicates slower cognitive decline, according to the EMA.
Lecanemab not for all patients
If the amyloid deposits have already caused irreversible damage to the brain, fighting them is no longer of any use. The EMA further restricts: The drug should only be used for Alzheimer’s patients who have only one or no copy of ApoE4 – a specific form of the gene for the protein apolipoprotein E.
They are less likely to experience certain serious side effects – swelling and bleeding in the brain – than people with two copies of ApoE4. According to experts, only a small fraction of Alzheimer’s sufferers are eligible for antibody therapy due to further restrictive requirements.
When do treatments with Lecanemab start in Germany?
It will likely be a few months before Lecanemab is used in Germany: approval by the EU Commission is still pending, and the manufacturer has also been obliged, for example, to develop detailed handouts and training courses for doctors, among others, and to create an observation register, explained Gabor Petzold, Director of Clinical Research at the DZNE.
Other means not so far yet
In July, the EU Medicines Agency decided that the risk of serious side effects was higher than the expected positive effect. The second test, which also took subgroup analyzes into account, came to a different result.
Lecanemab is not the only drug that is said to have a causal effect against Alzheimer’s: the antibody aducanumab, developed by the US biotech company Biogen, was not recommended for approval by the EMA at the end of 2021. The supposed clinical effect of the drug is questionable. Another application for approval was submitted by the US pharmaceutical company Eli Lilly for the active ingredient donanemab. This process is still ongoing.
Risks of treatment
According to the EMA, in patients treated with lecanemab with only one or no ApoE4 copy, edema in the brain occurred in 8.9 percent and microbleeds in 12.9 percent.
The swelling and microbleeds in the brain mostly remained without symptoms and were usually only noticed through imaging procedures such as magnetic resonance imaging (MRI). However, if it occurs repeatedly, there is a risk of reduced brain performance or coordination difficulties. Microbleeds are also considered a risk factor for larger, potentially life-threatening cerebral hemorrhages.
The EMA therefore emphasizes in its statement that there must be measures to minimize risks; such as MRI scans before administering further doses of lecanemab. Lecanemab is given as an intravenous infusion every two weeks.
Criticism of anti-Alzheimer drugs
Health experts criticize the therapies in the specialist journal “The BMJ”: The drugs only show an imperceptible slowing of dementia, but they show serious undesirable side effects, including death, it is said.
It is also questionable how relevant the measurable slight delay in the course of the disease is to everyday life, adds Walter Schulz-Schaeffer from the Saarland University Hospital in Homburg. Studies on the active ingredients also make the observation that anti-amyloid drugs noticeably shrink the brain. What this means is still completely unclear.
