How Leqembi became the biggest news in Alzheimer’s disease in 40 years, and what comes next
Betsy Groves, 73, with her granddaughter. Groves learned in 2021 that she has Alzheimer's disease. She hopes to take Leqembi, a drug approved by the FDA last week.
A few months ago, Betsy Groves traveled less than a mile from her home in Cambridge, Mass. to give a talk to a bunch of scientists. The scientists, who worked for the pharmaceutical companies Biogen and Eisai, wanted to know how she lived her life, how she thought about her future, and what it was like when a doctor’s appointment in 2021 gave her the worst possible news. Groves, 73, has Alzheimer’s disease. She caught it early, through a lumbar puncture that showed evidence of amyloid, an Alzheimer’s hallmark, in her cerebrospinal fluid. As a way of dealing with her diagnosis, she joined the Alzheimer’s Association’s National Early-Stage Advisory Board, which helped her shift into seeing her diagnosis as something she could use to help others.
After her talk, Groves stayed for lunch with the scientists, who were eager to put a face to their work. Biogen and Eisai were about to release the first drug to successfully combat Alzheimer’s in 40 years of experimental disaster. Their drug, which is known by the scientific name lecanemab and the marketing name Leqembi, was granted accelerated approval by the U.S. Food and Drug Administration last Friday, Jan. 6, after a study in 1,800 people showed that it reduced cognitive decline by 27 percent over 18 months.
It is no exaggeration to say that this result is a huge deal. The field of Alzheimer’s drug development has been absolutely littered with failures. Almost everything researchers have tried has tanked in clinical trials. “Most of the things that we've done have proven not to be effective, and it's not because we haven’t been taking a ton of shots at goal,” says Anton Porsteinsson, director of the University of Rochester Alzheimer's Disease Care, Research, and Education Program, who worked on the lecanemab trial. “I think it's fair to say you don't survive in this field unless you're an eternal optimist.”
As far back as 1984, a cure looked like it was within reach: Scientists discovered that the sticky plaques that develop in the brains of those who have Alzheimer’s are made up of a protein fragment called beta-amyloid. Buildup of beta-amyloid seemed to be sufficient to disrupt communication between, and eventually kill, memory cells. If that was true, then the cure should be straightforward: Stop the buildup of beta-amyloid; stop the Alzheimer’s disease.
It wasn’t so simple. Over the next 38 years, hundreds of drugs designed either to interfere with the production of abnormal amyloid or to clear it from the brain flamed out in trials. It got so bad that neuroscience drug divisions at major pharmaceutical companies (AstraZeneca, Pfizer, Bristol-Myers, GSK, Amgen) closed one by one, leaving the field to smaller, scrappier companies, like Cambridge-based Biogen and Tokyo-based Eisai. Some scientists began to dismiss the amyloid hypothesis altogether: If this protein fragment was so important to the disease, why didn’t ridding the brain of it do anything for patients? There was another abnormal protein that showed up in the brains of Alzheimer’s patients, called tau. Some researchers defected to the tau camp, or came to believe the proteins caused damage in combination.
The situation came to a head in 2021, when the FDA granted provisional approval to a drug called aducanumab, marketed as Aduhelm, against the advice of its own advisory council. The approval was based on proof that Aduhelm reduced beta-amyloid in the brain, even though one research trial showed it had no effect on people’s symptoms or daily life. Aduhelm could also cause serious side effects, like brain swelling and amyloid related imaging abnormalities (known as ARIA, these are basically micro-bleeds that appear on MRI scans). Without a clear benefit to memory loss that would make these risks worth it, Medicare refused to pay for Aduhelm among the general population. Two congressional committees launched an investigation into the drug’s approval, citing corporate greed, lapses in protocol, and an unjustifiably high price. (Aduhelm was also produced by the pharmaceutical company Biogen.)
To be clear, Leqembi is not the cure Alzheimer’s researchers hope for. While the drug is the first to show clear signs of a clinical benefit, the scientific establishment is split on how much of a difference Leqembi will make in the real world.
So far, Leqembi is like Aduhelm in that it has been given accelerated approval only for its ability to remove amyloid from the brain. Both are monoclonal antibodies that direct the immune system to attack and clear dysfunctional beta-amyloid. The difference is that, while that’s all Aduhelm was ever shown to do, Leqembi’s makers have already asked the FDA to give it full approval – a decision that would increase the likelihood that Medicare will cover it – based on data that show it also improves Alzheimer’s sufferer’s lives. Leqembi targets a different type of amyloid, a soluble version called “protofibrils,” and that appears to change the effect. “It can give individuals and their families three, six months longer to be participating in daily life and living independently,” says Claire Sexton, PhD, senior director of scientific programs & outreach for the Alzheimer's Association. “These types of changes matter for individuals and for their families.”
To be clear, Leqembi is not the cure Alzheimer’s researchers hope for. It does not halt or reverse the disease, and people do not get better. While the drug is the first to show clear signs of a clinical benefit, the scientific establishment is split on how much of a difference Leqembi will make in the real world. It has “a rather small effect,” wrote NIH Alzheimer’s researcher Madhav Thambisetty, MD, PhD, in an email to Leaps.org. “It is unclear how meaningful this difference will be to patients, and it is unlikely that this level of difference will be obvious to a patient (or their caregivers).” Another issue is cost: Leqembi will become available to patients later this month, but Eisai is setting the price at $26,500 per year, meaning that very few patients will be able to afford it unless Medicare chooses to reimburse them for it.
The same side effects that plagued Aduhelm are common in Leqembi treatment as well. In many patients, amyloid doesn’t just accumulate around neurons, it also forms deposits in the walls of blood vessels. Blood vessels that are shot through with amyloid are more brittle. If you infuse a drug that targets amyloid, brittle blood vessels in the brain can develop leakage that results in swelling or bleeds. Most of these come with no symptoms, and are only seen during testing, which is why they are called “imaging abnormalities.” But in situations where patients have multiple diseases or are prescribed incompatible drugs, they can be serious enough to cause death. The three deaths reported from Leqembi treatment (so far) are enough to make Thambisetty wonder “how well the drug may be tolerated in real world clinical practice where patients are likely to be sicker and have multiple other medical conditions in contrast to carefully selected patients in clinical trials.”
Porsteinsson believes that earlier detection of Alzheimer’s disease will be the next great advance in treatment, a more important step forward than Leqembi’s approval.
Still, there are reasons to be excited. A successful Alzheimer’s drug can pave the way for combination studies, in which patients try a known effective drug alongside newer, more experimental ones; or preventative studies, which take place years before symptoms occur. It also represents enormous strides in researchers’ understanding of the disease. For example, drug dosages have increased massively—in some cases quadrupling—from the early days of Alzheimer’s research. And patient selection for studies has changed drastically as well. Doctors now know that you’ve got to catch the disease early, through PET-scans or CSF tests for amyloid, if you want any chance of changing its course.
Porsteinsson believes that earlier detection of Alzheimer’s disease will be the next great advance in treatment, a more important step forward than Leqembi’s approval. His lab already uses blood tests for different types of amyloid, for different types of tau, and for measures of neuroinflammation, neural damage, and synaptic health, but commercially available versions from companies like C2N, Quest, and Fuji Rebio are likely to hit the market in the next couple of years. “[They are] going to transform the diagnosis of Alzheimer's disease,” Porsteinsson says. “If someone is experiencing memory problems, their physicians will be able to order a blood test that will tell us if this is the result of changes in your brain due to Alzheimer's disease. It will ultimately make it much easier to identify people at a very early stage of the disease, where they are most likely to benefit from treatment.”
Learn more about new blood tests to detect Alzheimer's
Early detection can help patients for more philosophical reasons as well. Betsy Groves credits finding her Alzheimer’s early with giving her the space to understand and process the changes that were happening to her before they got so bad that she couldn’t. She has been able to update her legal documents and, through her role on the Advisory Group, help the Alzheimer’s Association with developing its programs and support services for people in the early stages of the disease. She still drives, and because she and her husband love to travel, they are hoping to get out of grey, rainy Cambridge and off to Texas or Arizona this spring.
Because her Alzheimer’s disease involves amyloid deposits (a “substantial portion” do not, says Claire Sexton, which is an additional complication for research), and has not yet reached an advanced stage, Groves may be a good candidate to try Leqembi. She says she’d welcome the opportunity to take it. If she can get access, Groves hopes the drug will give her more days to be fully functioning with her husband, daughters, and three grandchildren. Mostly, she avoids thinking about what the latter stages of Alzheimer’s might be like, but she knows the time will come when it will be her reality. “So whatever lecanemab can do to extend my more productive ways of engaging with relationships in the world,” she says. “I'll take that in a minute.”
The Women of RNA: Two Award-Winners Share Why They Spent Their Careers Studying DNA's Lesser-Known Cousin
When Lynne Maquat, who leads the Center for RNA Biology at the University of Rochester, became interested in the ribonucleic acid molecule in the 1970s, she was definitely in the minority. The same was true for Joan Steitz, now professor of molecular biophysics and biochemistry at Yale University, who began to study RNA a decade earlier in the 1960s.
"My first RNA experiment was a failure, because we didn't understand how things worked," Steitz recalls. In her first undergraduate experiment, she unwittingly used a lab preparation that destroyed the RNA. "Unknowingly, our preparation contained enzymes that degraded our RNA."
At the time, scientists pursuing genetic research tended to focus on DNA, or deoxyribonucleic acid — and for good reason. It was clear that the enigmatic double-helix ribbon held the answers to organisms' heredity, genetic traits, development, growth and aging. If scientists could decipher the secrets of DNA and understand how its genetic instructions translate into the body's functions in health and disease, they could develop treatments for all kinds of diseases. On the contrary, the prevailing dogma of the time viewed RNA as merely a helper that passively carried out DNA's genetic instructions for protein-making — so it received much less attention.
But Maquat and Steitz weren't interested in heredity. They studied biochemistry and biophysics, so they wanted to understand how RNA functioned on the molecular level — how it carried instructions, catalyzed reactions, and helped build protein bonds, among other things.
"I'm a mechanistic biochemist, so I like to know how things happen," Maquat says. "Once you understand the mechanism, you can think of how to solve problems." And so the quest to understand how RNA does its job became the focus of both women's careers.
"People can now appreciate why some of us studied RNA for such a long time."
Half a century later, in 2021, their RNA work has earned two prestigious recognitions only months from each other. In February, they received the Wolf Prize in Medicine, followed by the Warren Alpert Foundation Prize in May, awarded to scientists whose achievements led to prevention, cure or treatments of human diseases.
It was the development of the COVID-19 vaccines that made RNA a household name. Made by Moderna and Pfizer, the vaccines use the RNA molecule to deliver genetic instructions for making SARS-CoV-2's characteristic spike protein in our cells. The presence of this foreign-looking protein triggers the immune system to attack and remember the pathogen. As the vaccines reached the finish line, RNA took center stage, and it was Maquat's and Steitz's research that helped reveal how these molecular cogwheels drive many biological functions within cells.
If you think of a cell as a kingdom, the DNA plays the role of a queen. Like a monarch in a palace, DNA nestles inside the cell's nucleus issuing instructions needed for the cell to function. But no queen can successfully govern without her court, her messengers, and her soldiers, as well as other players that make her kingdom work. That's what RNAs do — they act as the DNA's vassals. They carry instructions for protein assembly, catalyze reactions and supervise many other processes to make sure the cellular kingdom performs as it should.
There are a myriad of these RNA vassals in our cells, and each type has its own specific task. There are messenger RNAs that deliver genetic instructions for protein synthesis from DNA to ribosomes, the cells' protein-making factories. There are ribosomal RNAs that help stitch together amino acids to make proteins. There are transfer RNAs that can bring amino acids to this protein synthesis machine, keeping it going. Then there are circular RNAs that act as sponges, absorbing proteins to help regulate the activity of genes. And that's only the tip of the iceberg when it comes to RNA diversity, researchers say.
"We know what the most abundant and important RNAs are doing," says Steitz. "But there are thousands of different ones, and we still don't have a full knowledge of them."
Critical to RNA's proper functioning is a process called splicing, in which a precursor mRNA is transformed into mature, fully-functional mRNA — a phenomenon that Steitz's work helped elucidate. The splicing process, which takes place in cellular assembly lines, involves removing extra RNA sequences and stringing the remaining RNA pieces together. Steitz found that tiny RNA particles called snRNPs are crucial to this process. They act as handy helpers, finding and removing errant genetic material from the mRNA molecules.
A dysfunctional RNA assembly line leads to diseases, including many cancers. For instance, Steitz found that people with Lupus — an autoimmune disorder — have antibodies that mistakenly attack the little snRNP helpers. She also discovered that when snRNPs don't do their job properly, they can cause what scientists call mis-splicing, producing defective mRNAs.
Fortunately, cells have a built-in quality-control process that can spot and correct these mistakes, which is what Maquat studied in her work. In 1981, she discovered a molecular quality-control system that spots and destroys such incorrectly assembled mRNA. With the cryptic name "nonsense-mediated mRNA decay" or NMD, this process is vital to the health and wellbeing of a cellular kingdom in humans — because splicing mistakes happen far more often than one would imagine.
"We estimate that about a third of our mRNA are mistakes," Maquat says. "And nonsense-mediated mRNA decay cleans up these mistakes." When this quality-control system malfunctions, defective mRNA forge faulty proteins, which mess up the cellular machinery and cause disease, including various forms of cancer.
Scientists' newfound appreciation of RNA opens door to many novel treatments.
Now that the first RNA-based shots were approved, the same principle can be used for create vaccines for other diseases, the two RNA researchers say. Moreover, the molecule has an even greater potential — it can serve as a therapeutic target for other disorders. For example, Spinraza, a groundbreaking drug approved in 2016 for spinal muscular atrophy, uses small snippets of synthetic genetic material that bind to the RNA, helping fix splicing errors. "People can now appreciate why some of us studied RNA for such a long time," says Maquat.
Steitz is thrilled that the entire field of RNA research is enjoying the limelight. "I'm delighted because the prize is more of a recognition of the field than just our work," she says. "This is a more general acknowledgment of how basic research can have a remarkable impact on human health."
Lina Zeldovich has written about science, medicine and technology for Popular Science, Smithsonian, National Geographic, Scientific American, Reader’s Digest, the New York Times and other major national and international publications. A Columbia J-School alumna, she has won several awards for her stories, including the ASJA Crisis Coverage Award for Covid reporting, and has been a contributing editor at Nautilus Magazine. In 2021, Zeldovich released her first book, The Other Dark Matter, published by the University of Chicago Press, about the science and business of turning waste into wealth and health. You can find her on http://linazeldovich.com/ and @linazeldovich.
In 2010, a 67-year-old former executive assistant for a Fortune 500 company was diagnosed with mild cognitive impairment. By 2014, her doctors confirmed she had Alzheimer's disease.
As her disease progressed, she continued to live independently but wasn't able to drive anymore. Today, she can manage most of her everyday tasks, but her two daughters are considering a live-in caregiver. Despite her condition, the woman may represent a beacon of hope for the approximately 44 million people worldwide living with Alzheimer's disease. The now 74-year-old is among a small cadre of Alzheimer's patients who have undergone an experimental ultrasound procedure aimed at slowing cognitive decline.
In November 2020, Elisa Konofagou, a professor of biomedical engineering and director of the Ultrasound and Elasticity Imaging Laboratory at Columbia University, and her team used ultrasound to noninvasively open the woman's blood-brain barrier. This barrier is a highly selective membrane of cells that prevents toxins and pathogens from entering the brain while allowing vital nutrients to pass through. This regulatory function means the blood-brain barrier filters out most drugs, making treating Alzheimer's and other brain diseases a challenge.
Ultrasound uses high-frequency sound waves to produce live images from the inside of the human body. But scientists think it could also be used to boost the effectiveness of Alzheimer's drugs, or potentially even improve brain function in dementia patients without the use of drugs.
The procedure, which involves a portable ultrasound system, is the culmination of 17 years of lab work. As part of a small clinical trial, scientists positioned a sensor transmitting ultrasound waves on top of the woman's head while she sat in a chair. The sensor sends ultrasound pulses throughout the target region. Meanwhile, investigators intravenously infused microbubbles into the woman to boost the effects of the ultrasound. Three days after the procedure, scientists scanned her brain so that they could measure the effects of the treatments. Five months later, they took more images of her brain to see if the effects of the treatment lasted.
Promising Signs
After the first brain scan, Konofagou and her team found that amyloid-beta, the protein that clumps together in the brains of Alzheimer's patients and disrupts cell function, had declined by 14%. At the woman's second scan, amyloid levels were still lower than before the experimental treatment, but only by 10% this time. Konofagou thinks repeat ultrasound treatments given early on in the development of Alzheimer's may have the best chance at keeping amyloid plaques at bay.
This reduction in amyloid appeared to halt the woman's cognitive decline, at least temporarily. Following the ultrasound treatment, the woman took a 30-point test used to measure cognitive impairment in Alzheimer's. Her score — 22, indicating mild cognitive impairment — remained the same as before the intervention. Konofagou says this was actually a good sign.
"Typically, every six months an Alzheimer's patient scores two to three points lower, so this is highly encouraging," she says.
Konofagou speculates that the results might have been even more impressive had they applied the ultrasound on a larger section of the brain at a higher frequency. The selected site was just 4 cubic centimeters. Current safety protocols set by the U.S. Food and Drug Administration stipulate that investigators conducting such trials only treat one brain region with the lowest pressure possible.
The Columbia trial is aided by microbubble technology. During the procedure, investigators infused tiny, gas-filled spheres into the woman's veins to enhance the ultrasound reflection of the sound waves.
The big promise of ultrasound is that it could eventually make drugs for Alzheimer's obsolete.
"Ultrasound with microbubbles wakes up immune cells that go on to discard amyloid-beta," Konofagou says. "In this way, we can recover the function of brain neurons, which are destroyed by Alzheimer's in a sort of domino effect." What's more, a drug delivered alongside ultrasound can penetrate the brain at a dose up to 10 times higher.
Costas Arvanitis, an assistant professor at Georgia Institute of Technology who studies ultrasonic biophysics and isn't involved in the Columbia trial, is excited about the research. "First, by applying ultrasound you can make larger drugs — picture an antibody — available to the brain," he says. Then, you can use ultrasound to improve the therapeutic index, or the ratio of the effectiveness of a drug versus the ratio of adverse effects. "Some drugs might be effective but because we have to provide them in high doses to see significant responses they tend to come with side effects. By improving locally the concentration of a drug, you open up the possibility to reduce the dose."
The Columbia trial will enroll just six patients and is designed to test the feasibility and safety of the approach, not its efficacy. Still, Arvantis is hopeful about the potential benefits of the technique. "The technology has already been demonstrated to be safe, its components are now tuned to the needs of this specific application, and it's safe to say it's only a matter of time before we are able to develop personalized treatments," he says.
Konofagou and her colleagues recently presented their findings at the 20th Annual International Symposium for Therapeutic Ultrasound and intend to publish them in a scientific journal later this year. They plan to recruit more participants for larger trials, which will determine how effective the therapy is at improving memory and brain function in Alzheimer's patients. They're also in talks with pharmaceutical companies about ways to use their therapeutic approach to improve current drugs or even "create new drugs," says Konofagou.
A New Treatment Approach
On June 7, the FDA approved the first Alzheimer's disease drug in nearly two decades. Aducanumab, a drug developed by Biogen, is an antibody designed to target and reduce amyloid plaques. The drug has already sparked immense enthusiasm — and controversy. Proponents say the drug is a much-needed start in the fight against the disease, but others argue that the drug doesn't substantially improve cognition. They say the approval could open the door to the FDA greenlighting more Alzheimer's drugs that don't have a clear benefit, giving false hope to both patients and their families.
Konofagou's ultrasound approach could potentially boost the effects of drugs like aducanumab. "Our technique can be seamlessly combined with aducanumab in early Alzheimer's, where it has shown the most promise, to further enhance both its amyloid load reduction and further reduce cognitive deficits while using exactly the same drug regimen otherwise," she says. For the Columbia team, the goal is to use ultrasound to maximize the effects of aducanumab, as they've done with other drugs in animal studies.
But Konofagou's approach could transcend drug controversies, and even drugs altogether. The big promise of ultrasound is that it could eventually make drugs for Alzheimer's obsolete.
"There are already indications that the immune system is alerted each time ultrasound is exerted on the brain or when the brain barrier is being penetrated and gets activated, which on its own may have sufficient therapeutic effects," says Konofagou. Her team is now working with psychiatrists in hopes of using brain stimulation to treat patients with depression.
The potential to modulate the brain without drugs is huge and untapped, says Kim Butts Pauly, a professor of radiology, electrical engineering and bioengineering at Stanford University, who's not involved in the Columbia study. But she admits that scientists don't know how to fully control ultrasound in the brain yet. "We're only at the starting point of getting the tools to understand and harness how ultrasound microbubbles stimulate an immune response in the brain."
Meanwhile, the 74-year-old woman who received the ultrasound treatment last year, goes on about her life, having "both good days and bad days," her youngest daughter says. COVID-19's isolation took a toll on her, but both she and her daughters remain grateful for the opportunity to participate in the ultrasound trial.
"My mother wants to help, if not for herself, then for those who will follow her," the daughter says. She hopes her mother will be able to join the next phase of the trial, which will involve a drug in conjunction with the ultrasound treatment. "This may be the combination where the magic will happen," her daughter says.