Scientists have hailed as revolutionary the first medical treatment that slows brain degeneration in Alzheimer’s disease. A breakthrough in research has ended decades of failure and shown that a new era of drugs to treat Alzheimer’s disease, the most common form of dementia, is possible. However, the new drug called Lekanemab has only a partial effect and there are still debates about its effectiveness.
In addition, the drug works in the early stages of the disease, so unless there is a similar breakthrough in diagnosis, it will not help the majority of people. Leconemab targets a protein called beta-amyloid that accumulates in the brains of people with Alzheimer’s disease. Lenkanemab is an antibody similar to those produced by the body to fight viruses or bacteria. It tells the immune system to clear the brain of amyloid. Amyloid is a protein that accumulates in the spaces between nerve cells in the brain and forms the characteristic plaques that are the hallmark of Alzheimer’s disease.
A large study involved 1,795 volunteers with early-stage Alzheimer’s disease. They received the drug every two weeks.
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Alzheimer’s disease has long defied the best efforts of doctors, so it’s not surprising that some see the new drug as a triumph. The charity Alzheimer’s Research UK said the results were significant. Professor John Hardy, one of the world’s leading researchers who proposed the idea of targeting amyloid 30 years ago, called the drug historic and said optimistically: “We are witnessing the beginning of the treatment of Alzheimer’s disease.” Professor Tara Spiers-Jones of the University of Edinburgh says the results are “a big event because we have been getting 100% negative results for a long time”. Currently, people with Alzheimer’s disease are prescribed other medications that help manage symptoms, but none of them change the course of the disease.
The results, presented at the Clinical Trials on Alzheimer’s Disease conference in San Francisco and published in the New England Journal of Medicine, do not make lecanemab a panacea. The disease continued to affect the brain, but over the course of 18 months of treatment, this process slowed by about a quarter. U.S. regulators are reviewing the results and are expected to make a decision soon on whether to approve lecanemab for widespread use. The drug’s developers – pharmaceutical companies Eisai and Biogen – plan to begin the process of drug approval in other countries next year.
David Essam and his wife Sheryl participate in clinical trials. British David Essam, who is 78 years old, participated in international clinical trials. He worked as a carpenter, but due to Alzheimer’s he had to give up his job – he could no longer remember how to assemble a cabinet or use tools. He has to use digital watches – he can no longer tell the time by looking at the face. “He is not the same person he used to be, he needs help with many things, his memory is almost nonexistent,” says his wife, Cheryl. But, she says, clinical trials of lecanemab have given the family hope. “If someone is able to slow down the progression of Alzheimer’s and eventually stop it completely, that would be great, because this disease is a terribly unpleasant thing,” says David himself.
More than 55 million people worldwide suffer from Alzheimer’s disease, and the number is expected to reach 139 million by 2050. Scientists and doctors are debating how important Lekanemab will be in real life. The slowing of the deterioration of the condition was achieved by the use of the drug, as evidenced by the evaluation of the patient’s symptoms. An 18-point scale was used, with symptoms ranging from normal to severe dementia. Those who received the new drug improved by an average of 0.45 points. Professor Spires-Jones admits that the effect is small, but she says she is willing to accept it. Dr. Susan Colhas of Alzheimer’s Research UK believes that although the new drug’s effect may seem modest, it is only the beginning and the next generation of drugs will be better. From a scientific point of view, it is likely that the drug’s effectiveness will be higher in longer trials. “I don’t think these results should be considered definitive,” says Dr. Colhas.
The drug lecanemab has side effects. Brain scans showed a risk of brain hemorrhage (17% of participants) and brain edema (13%). Overall, 7% of people taking the drug had to stop taking it because of side effects. The most important question is what happens after 18 months of clinical trials, and there is no exact answer yet. Dr. Elizabeth Coulthard, who treats patients at a hospital in Bristol, says that patients typically have an average of six years of independent living left after the onset of mild cognitive impairment symptoms. “If we slow this decline by a quarter, it could potentially last another 19 months,” she says.
The emergence of drugs that truly change the course of disease raises another question: is the healthcare system ready to use them? Medications should be prescribed in the early stages of the disease, before too much brain damage has occurred. However, the majority of people who seek medical attention for memory problems are usually in the late stages of the disease. For lecanemab to be effective, people must seek help at the first sign of memory problems, and doctors must be able to refer them for amyloid imaging of the brain or cerebrospinal fluid analysis to determine the presence of Alzheimer’s disease or another form of dementia. Currently, only 1-2% of people with dementia undergo such tests. “There is a huge gap between the current level of medical care and what is needed to treat the disease,” says Dr. Kultkhard.
According to her, the drug can currently only help those who live near major medical centers or receive private medical assistance. Scientists also emphasize that amyloid is only part of the complex picture of brain damage in Alzheimer’s disease. The immune system and inflammatory processes play a major role in the disease, and another toxic protein, tau, is found where brain cells die. Professor Spiers-Jones believes that new research should be conducted in this direction. “I am very happy that we are on the verge of understanding the problem sufficiently and that in a decade or so there should be something that will change the situation for the better,” she adds.
Kate Lee, chief executive of the charity Alzheimer’s Society, called for the development of a 10-year government strategy on dementia to tackle what she described as the UK’s biggest health crisis. In an interview with the BBC, she also said that lecanemab will not have a significant impact on those who already have dementia, but it should change the situation significantly for future generations.