The best ever drug for Alzheimer’s disease has been found to slow decline by a third, in a breakthrough that ushers in a new era of treatment for dementia. On May 3, US pharmaceutical giant Eli Lilly announced that its drug donanemab delays the worsening of symptoms by 35 per cent.
In half of patients, the drug completely halted mental decline for more than a year. Experts have described the results as “remarkable”. British scientists hailed the trial results as “hugely exciting”, while the Alzheimer’s Society said the drug signaled “the beginning of the end of Alzheimer’s disease”.
“This result confirms that we are now entering the treatment era of Alzheimer’s disease,” said Dr Cath Mummery, consultant neurologist at University College London Hospitals NHS Foundation Trust. “The decades-long battle to find treatments that change Alzheimer’s disease is changing.
“We are now entering the time of disease modification, where we might realistically hope to treat and maintain someone with Alzheimer’s disease, with long-term disease management, rather than palliative and supportive care.”
So, what makes this drug different? Current drugs for dementia work by boosting chemical signals in the brain or treating symptoms such as insomnia or depression, but cannot stop the progression. Donanemab works by clearing the brain of sticky amyloid plaques that prevent brain cells from communicating.
In recent years, scientists have doubted whether removing amyloid was the correct strategy, after the failure of several trials of drugs to break up the plaques. John Hardy, professor of Neuroscience at University College London (UCL) said the trial results should “dispel any lingering doubts” that the way to treat Alzheimer’s was to remove amyloid from the brain.
The new study involved 1,182 patients with early Alzheimer’s disease, including mild cognitive impairment, who were given monthly infusions of donanemab. As well as postponing a worsening of clinical symptoms, the drug also allowed patients to continue to perform daily activities for longer, such as shopping, housekeeping, managing their finances and taking medication.
The study also enrolled 552 people who were at a later stage of Alzheimer’s. Results showed the drug slowed down disease progression by up to 29 per cent. However, researchers warned that the drugs did carry some troubling side effects, such as brain swelling and bleeding. One in four trial participants suffered swelling or bleeding, and three people died from the side effects.
It is the second Alzheimer’s drug to prove successful in the past year after Eisai/Biogen’s lecanemab was shown to slow decline by 27 per cent.
According to the CDC, current estimates are that about 5.8 million people in the United States have Alzheimer’s disease and related dementias, including 5.6 million aged 65 and older and about 200,000 under age 65 with younger-onset Alzheimer’s. By 2060, the number of Alzheimer’s disease cases is predicted to rise to an estimated 14 million people, with minority populations being affected the most.
Over 6 million Americans are currently living with Alzheimer’s disease, which costs the U.S. economy an estimates $321 billion in 2022, in addition to an estimated $271 billion in unpaid caregiving. By 2050, the number of Americans living with Alzheimer’s is expected to reach 12.7 million, bringing the total cost to nearly $1 trillion each year.
Eli Lilly said it would apply to the US Food and Drug Administration (FDA) for approval this quarter and “will proceed with global regulatory submissions as quickly as possible”. Lecanemab received FDA approval in January.
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