New medicine may slow cognitive decline

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The latest clinical trial with lecanemab has yielded promising results for Alzheimer’s patients. Dobrila Vignjevic/Getty Images
  • More than 55 million people globally have dementia, with Alzheimer’s disease contributing to 60-70% of cases.
  • Phase 3 clinical trial results shared in a press release suggest that a new drug called lecanemab helps slow cognitive decline in Alzheimer’s patients by 27% after 18 months of treatment.
  • The investigators expect the US drug regulator to do so make a decision on the new drug in early January 2023.

More than 55 million people around the world have dementia, with the most common form of Alzheimer’s disease contributing to 60-70% of these cases.

Cognitive decline, including memory loss, difficulty performing certain tasks and recognition problems, are common symptoms of Alzheimer’s disease. These symptoms usually worsen as the disease progresses progressing.

Phase 3 clinical trial results for a new drug called lecanemab now suggest that the drug can help slow the rate of cognitive decline in people with early Alzheimer’s disease by 27% after 18 months of treatment.

Lecanemab is a humanized study monoclonal antibody for the treatment of mild cognitive impairment due to Alzheimer’s disease. It was developed by pharmaceutical companies Eisai Co., Ltd. and Biogen Inc.

According to Dr. Sharon Cohen, a neurologist and medical director of the Toronto Memory Program in Toronto, Canada, and part of the study team for the phase 3 clinical trial, lecanemab is an antibody given by intravenous infusion that works by clearing amyloid from the brain.

“Amyloid is a toxic protein that accumulates early in Alzheimer’s disease and is responsible, not only for direct damage to brain cell function, but also leads to a cascade of other toxic processes that further damage the brain,” she explained to Medical News Today.

“When amyloid is cleared by lecanemab early in the disease, the disease progresses more slowly, allowing individuals to maintain their cognition and independence for longer,” added Dr. Cohen.

Amyloid, also known as beta-amyloid protein, is a sticky substance that, if left alone, forms plaques in the brain. These plaques disrupt communication between brain cells. Previous research shows that greater plaque build-up is associated with greater memory loss.

“The top-line results of the Clarity trial showed a 27% reduction in disease on the primary clinical endpoint for those treated with lecanemab, and this was highly statistically significant.”
— Dr. Sharon Cohen

Dr. Cohen said currently approved drugs for Alzheimer’s disease, which are available in most countries, only treat symptoms and do not affect the underlying early brain changes of the disease.

“As such, these medications act relatively late in the disease and do not stabilize or slow brain cell destruction or related loss of function. Furthermore, the benefit of currently available symptomatic treatments is very modest,” she elaborated.

“Finally, the current symptom treatments are not approved for the pre-dementia stage of Alzheimer’s disease, and therefore [most] people with mild cognitive impairment due to Alzheimer’s disease get significantly worse before they are eligible for these treatments,” continued Dr. Cohen.

“This is of course contrary to the principle that early initiation of treatment is desirable for a slowly progressive disease,” she added.

According to Dr. Scott Kaiser, a geriatrician and director of geriatric cognitive health for the Pacific Neuroscience Institute in Santa Monica, California, for a long time there was no medicine to treat Alzheimer’s disease.

“Then we had drugs that could help treat symptoms, but there haven’t been any disease-modifying drugs—something that could actually treat the underlying pathology and slow the progression of the disease,” he said.

Then said Dr. Kaiser that the drug aducanumab was discovered.

“Aducanumab … was one of these first monoclonal antibodies targeting subunits of this beta-amyloid,” he said.

“[Aducanumab] was really controversial because when aducanumab came out and went through FDA review, their studies … showed definitively that these drugs were good at removing amyloid, but they weren’t able to definitively show that this had a clinical effect . It is one thing to remove these plaques from the brain, but another thing to actually improve people’s thinking, functioning and overall life,” he elaborated.

“[With the Phase 3 clinical trial results for lecanemab] it appears that there is an impact on the underlying pathology and some positive clinical effect for people who have mild cognitive impairment for early Alzheimer’s disease. And it’s a paradigm shift – it’s really an exciting new direction.”
— Dr. Scott Kaiser

“Now experts (will) debate – how meaningful is the ‘clinical effect’? If you can show a small change on a complex scale, it can be numerically significant. But does it really matter in terms of human health, well-being, function and (and) quality of life? There will be a solid debate going forward,” he added.

According to Dr. Cohen, lecanemab can cause a side effect known as Amyloid-related imaging abnormality (ARIA).

“This is a side effect common to most anti-amyloid antibodies and seen mainly on MRI brain scans. There are two types of ARIA: ARIA-E which refers to edema or swelling in the brain; and ARIA-H which refers to microscopic bleeding,” she explained.

“Importantly, the rate of ARIA with lecanemab is low – 12.5% ​​for ARIA-E and 17% for ARIA-H. And in most cases of ARIA there are no symptoms – symptoms occur in only 2.8% with ARIA -E and in only 0.7% with ARIA-H. Furthermore, ARIA usually resolves spontaneously and can be managed and monitored.”
— Dr. Sharon Cohen

Medical News Today also spoke with Dr. Ronald Petersen, neurologist and director of the Mayo Clinic’s Alzheimer’s Disease Research Center, on possible side effects of lecanemab. He also mentioned ARIA-E brain swelling.

“However, many of these patients did not experience any related symptoms,” he said. “The incidence of the side effects was lower than in similar experimental drugs. With the monitoring of a doctor, these side effects appeared to be manageable,” he told MNT.

According to Dr. Cohen will present the Phase 3 clinical trial results at the Clinical Trials on Alzheimer’s Disease Congress (CTAD) in November 2022, with publication in a peer-reviewed medical journal to follow.

“The FDA has agreed that the Clarity study will serve as a confirmatory trial for lecanemab in people with mild cognitive impairment and mild dementia due to Alzheimer’s disease. The FDA will make a decision on the approval of lecanemab by January 6, 2023,” it added she.

Dr. Cohen also mentioned that several other studies with lecanemab are underway to develop additional treatment options, including:

Dr. Mary Sano, director of the Alzheimer’s Disease Research Center, professor in the Department of Psychiatry and associate dean for clinical research at Mount Sinai School of Medicine, said MNT she was pleased to see a drug meet all of its proposed primary and secondary endpoints.

However, she said a full report will be important to fully understand the safety of lecanemab.

“The current medication is also delivered via an infusion every two weeks, which can be quite burdensome. It will be important to explore ways to have the most effective and cost-effective delivery system,” added Dr. Sano.

Dr. Petersen said the news about lecanemab is “very good news” for Alzheimer’s disease patients and their families.

“Although this is not a cure for the disease, it represents a step in the right direction in slowing cognitive decline. These data suggest that we can intervene in the amyloid process and slow it down. Now we need to move earlier in the disease process to treat people who are amyloid-positive but clinically normal.”
— Dr. McCarthy. Ronald Petersen

Dr. Kaiser also called the Phase 3 clinical trial results “positive” and “encouraging.” However, he said there could be controversy in the coming days with different expert opinions, as well as debates about the potential cost of lecanemab and how to ensure fair and equal access.

New medicine may slow cognitive decline

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