How Leqembi became the biggest news in Alzheimer’s disease in 40 years, and what comes next
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.”
A few days before Christmas 2015, Paige Alexandria, a 28-year-old counselor at the Austin Women's Health Center in Texas, found out she was pregnant.
Alexandria had missed the cutoff for a medication abortion by three days.
"It was an unplanned pregnancy, and instantaneously I knew I needed an abortion," Alexandria recalls. Already a mother of two children, one with special needs, a third child was not something Alexandria and her husband felt prepared to take on. "Mentally, I knew my limit. I wasn't prepared for a third and I didn't want one," she says.
At an ultrasound appointment one week later, scans showed she was a little over eight weeks pregnant. Alexandria opted to have an abortion as soon as possible, and preferably with medication. "I really wanted to avoid a surgical abortion," she says. "It sounded a lot more invasive, and I'm already uncomfortable with pap smears and pelvic exams, so I initially went in wanting to do the pill."
But at the time, medication guidelines stipulated that one of the pills, called Mifepristone, could only be prescribed to end a pregnancy at eight weeks gestation or earlier – Alexandria had missed the cutoff by three days. If she wanted to end the pregnancy, she would need to undergo a surgical abortion, otherwise known as a vacuum aspiration abortion.
With a vacuum aspiration abortion, doctors dilate the cervix and manually aspirate out the contents of the uterus. Medication abortion, on the other hand, consists of the patient taking two pills – Mifepristone, which blocks the hormones that help the pregnancy develop, and Misoprostol, which empties the uterus over a period of days, identical to a miscarriage.
Alexandria was upset about the change of plans but resolute in her decision to end the pregnancy. "The fact that I didn't really have a choice in how my procedure was performed has made the experience just a little more sensitive for me," she says. She scheduled the earliest available appointment for a surgical abortion.
Paige Alexandria would have chosen to terminate her pregnancy with medication if the regulations were less stringent.
(Photo courtesy of Alexandria)
Like Alexandria, many people looking to terminate a pregnancy opt to do so with medication. According to research from the Guttmacher Institute, medication abortions accounted for nearly 40 percent of all abortions in the year 2017 – a marked increase from 2001, when medication abortions only accounted for roughly five percent of terminations. Taken 24-48 hours apart, Mifepristone and Misoprostol have a 95-99 percent success rate in terminating pregnancies up to 63 days – or nine weeks – of gestation, according to the American College of Obstetrics and Gynecology (ACOG).
But even though the World Health Organization (WHO) considers medical abortion to be highly safe and effective, the medication is still carefully guarded in the United States: Mifepristone is only available for terminating pregnancies up to 10 weeks gestation, per the FDA, even though limited research suggests that both are safe and effective at terminating pregnancies between 12 and 20 weeks.
Additionally, a separate set of regulations known as a Risk Evaluation and Mitigation Strategy (REMS) means that patients can only take Mifepristone under specific circumstances. Mifepristone must be distributed in person by a healthcare provider – usually interpreted in most states as a doctor or nurse practitioner – who has registered with the drug's manufacturer. The medication cannot be distributed through a pharmacy, so doctors who wish to provide the drug must stock the medication in-office, and both the provider and the patient must sign a form that warns them of the "risk of serious complications associated with Mifepristone," according to the FDA.
"REMS is a set of restrictions that the FDA puts on the distribution of drugs it considers dangerous or risky in some way," says Dr. Elizabeth Raymond, an OB-GYN and senior medical associate at Gynuity Health Projects. Although not always called REMS, these restrictions have been imposed on Mifepristone since the medication was approved by the FDA in 2000, Raymond says.
Raymond is part of a growing number of physicians and researchers who want to eliminate the REMS requirements for Mifepristone, also known by its brand name Mifeprex. In 2017, Raymond and several other physicians authored a paper in the New England Journal of Medicine (NEJM) arguing that Mifepristone is extremely safe and needlessly over-regulated.
"When the FDA first approved [Mifepristone] and imposed these requirements, they might have made sense 19 years ago when there was limited information about the use of this treatment in the United States," says Dr. Daniel Grossman, director at Advancing New Standards in Reproductive Health at UCSF and co-author of the 2017 report in the NEJM. "Now, after 19 years, it's clear that this medication is very safe, and safer than a lot of others available in a pharmacy."
Since 2000, Mifepristone has been implicated in 19 deaths, making its mortality rate 0.00063 percent.
According to their research, over three million people have taken Mifepristone since it was approved in 2000. Since then, Mifepristone has been implicated in 19 deaths, making its mortality rate 0.00063 percent. Even then, the risk is inflated, Grossman says.
"The requirement is that practitioners need to report any deaths that occur after taking these medications, and so you'll see deaths included in that figure which are homicides or suicides or something unrelated to taking Mifepristone," says Grossman. In contrast, Acetaminophen – better known as Tylenol – was associated with 458 overdose deaths between 1990 and 1998, as well as 56,000 emergency room visits and 26,000 hospitalizations. Sildenafil, better known as Viagra, was linked to 762 deaths in the first twenty months after it was approved by the FDA. Yet neither Tylenol nor Viagra have been burdened with the same REMS restrictions as Mifepristone.
"It's clearly about more than just the safety of the medication at this point," says Grossman. "It's more about stigma related to abortion and politics."
For people who want a medication abortion, the REMS requirements mean they often need to take off work to schedule a doctor's appointment, arrange for transportation and childcare, and then arrange an additional doctor's appointment days afterward to take the second dose of medication. While surgical abortion procedures are quicker (usually a one-day outpatient procedure, depending on gestation), many people prefer having the abortion in the comfort of their home or surrounded by family instead.
Paige Alexandria, who counsels people seeking abortions at her job, says that survivors of sexual violence often prefer medical abortions to surgical ones. "A lot of time survivors have a trauma associated with medical instruments or having pelvic exams, and so they're more comfortable taking a pill," she says.
But REMS also creates a barrier for healthcare providers, Grossman says. Stocking the medication in-office is "a hassle" and "expensive," while others are reluctant to register their name with the drug manufacturer, fearing harassment or violence from anti-choice protestors. As a result, the number of practitioners willing to provide medical abortions nationwide is severely limited. According to Grossman's own research published in the journal Obstetrics and Gynecology, 28 percent of OBGYNs admitted they would administer medication abortions if it were possible to write a prescription for Mifepristone rather than stock it in-office.
Amazingly, the restrictions on Mifepristone have loosened since it first came on the market. In 2016, the FDA updated the guidelines on Mifepristone to allow its use until 10 weeks gestation, up from eight weeks. But doctors say the REMS restrictions should be eliminated completely so that people can obtain abortions as early as possible.
"REMS restrictions inhibit people from being able to get a timely abortion," says Raymond, who stresses that abortion is generally more comfortable, more affordable, and safer for women the earlier it's done. "Abortion is very safe no matter when you get it, but it's also easier because there's less risk for bleeding, infections, or other complications," Raymond says. Abortions that occur earlier than eight weeks of gestation have a complication rate of less than one percent, while an abortion done at 12 or 13 weeks has a three to six percent chance of complications.
And even for people who want a medication abortion early on in their pregnancy, REMS restrictions make it so that they may not have time to obtain it before the 10-week period lapses, Raymond says.
"If you're seven weeks pregnant but it takes you three weeks to figure out travel and childcare arrangements to go into the doctor and take this medication, now you're at the cutoff date," she says. "Even if you manage to get an abortion at nine weeks, that's still a later gestational age, and so the risks are increased."
In 2016, at a little over nine weeks gestation, Alexandria completed her abortion by having a D&E. But because she didn't have anyone to drive her home after the procedure, she wasn't able to have sedation throughout, something she describes as "traumatic."
"I had the abortion completely aware and coherent, and paired with the fact that I hadn't even wanted a surgical abortion in the first place made it harder to deal with," Alexandria says.
"When you're just a day or two past eight weeks and you want an abortion – why is medication not immediately available?"
Today, Alexandria shares her story publicly to advocate for abortion care. Although she doesn't regret her surgical abortion and acknowledges that not everyone experiences surgical abortion the same way she did, she does wish that she could have gone a different route.
"If I had to do it over, I would still try to do the pill, because [the surgical abortion] was such a terrifying experience," she says. "When you're just a day or two past eight weeks and you want an abortion – why is medication not immediately available? It just doesn't make sense."
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Kira Peikoff was the editor-in-chief of Leaps.org from 2017 to 2021. As a journalist, her work has appeared in The New York Times, Newsweek, Nautilus, Popular Mechanics, The New York Academy of Sciences, and other outlets. She is also the author of four suspense novels that explore controversial issues arising from scientific innovation: Living Proof, No Time to Die, Die Again Tomorrow, and Mother Knows Best. Peikoff holds a B.A. in Journalism from New York University and an M.S. in Bioethics from Columbia University. She lives in New Jersey with her husband and two young sons. Follow her on Twitter @KiraPeikoff.