• Posted July 17, 2023

Experimental Alzheimer's Drug Slows Thinking Declines in Late-Stage Trial

Another experimental drug meant to slow the damage of Alzheimer's appears poised to join a growing arsenal of new treatments for this memory-robbing disease.

In research published online Monday in the Journal of the American Medical Association and presented simultaneously at the Alzheimer's Association International Conference in Amsterdam, the drug donanemab slowed memory and thinking declines in early symptomatic Alzheimer's patients by more than one-third. About 47% of those taking the medication had no decline on a key measure of thinking over a year, compared to 29% of patients on a placebo.

"If approved, we believe donanemab can provide clinically meaningful benefits for people with this disease and the possibility of completing their course of treatment as early as 6 months once their amyloid plaque is cleared," Anne White, executive vice president of Eli Lilly and president of Lilly Neuroscience, said in a company news release. "We must continue to remove any barriers in access to amyloid-targeting therapies and diagnostics in an already complex healthcare ecosystem for Alzheimer's disease."

The company added that it has already completed an application for traditional approval from the U.S. Food and Drug Administration.

"People living with early, symptomatic Alzheimer's disease are still working, enjoying trips, sharing quality time with family — they want to feel like themselves, for longer," Dr. Mark Mintun, group vice president of neuroscience research & development at Lilly, said in the company news release. "The results of this study reinforce the importance of diagnosing and treating disease sooner than we do today."

About 52% of the patients in the trial were able to stop taking the medication by one year because of its effectiveness. About 72% could do so by a year and a half, the company said.

In the trial, a group with intermediate levels of a brain protein known as tau had a 35% slowing in cognitive and functional decline. In the intermediate group combined with a group with higher tau levels, slowing in decline was 22%.

Despite the promising results, four editorials that were published alongside the trial results raised concerns about cost, access and safety risks.

"The modest benefits would likely not be questioned by patients, clinicians or payers if amyloid antibodies were low-risk, inexpensive and simple to administer," wrote experts led by Dr. Eric Widera, from the University of California, San Francisco (UCSF). "However, they are none of these."

Other editorials also offered caveats on the findings.

"Donanemab was very effective at eliminating its target, cerebral amyloid, but the clinical effect was comparatively weak," wrote Jennifer Manly and Kacie Deters, from the Taub Institute for Research on Alzheimer's Disease and the Aging Brain at Columbia University and the University of California, Los Angeles, respectively. "By the end of the trial (76 weeks), amyloid plaques were cleared in 80% of the treatment group. Overall, cognition and daily function continued to decline in all participants, but treatment with donanemab delayed progression on the primary outcome... by about 4 months," they noted.

"While the slowing of clinical decline seen in this trial represents an important start, and may be deemed clinically meaningful for some patients, development of more impactful and safer treatments is still needed," wrote Dr. Gil Rabinovici and Renaud La Joie, from UCSF's Memory and Aging Center.

"Current trials are evaluating whether [amyloid]-targeting monoclonal antibodies may be more effective at the preclinical stage of AD [Alzheimer's disease], and ultimately it seems likely that a combination of drugs targeting additional molecular pathways involved in AD pathophysiology will be needed to more profoundly affect the trajectory of disease," they added.

Another new Alzheimer's drug, Eisai and Biogen's Leqembi, was fully approved earlier this month.

But that drug carries similar risks, Widera's team noted.

"The harms include infusion reactions and amyloid-related imaging abnormalities [ARIA]," his team wrote in the editorial. "Although ARIA may often be asymptomatic to mild in nature, they can lead to life-threatening events, including what was likely 3 treatment-related deaths in each of the donanemab and lecanemab studies."

Apart from safety risks, there is the issue of cost and access, a fourth editorial pointed out.

"Both the potential for high out-of-pocket costs and the fact that treatment with donanemab will require trips to a provider with infusion and advanced imaging capacity are likely to serve as unequally distributed barriers to access," wrote Meredith Rosenthal, from the department of health policy and management at the Harvard School of Public Health, in Boston.

"Particular concern may be warranted for rural patients, those with lower incomes who do not qualify for Medicaid (a larger concern in states with less generous Medicaid programs, such as those that have not participated in the Affordable Care Act expansion) and those who lack reliable transportation," Rosenthal noted.

"Moreover, Black patients, who are disproportionately diagnosed with [Alzheimer's disease], are 1.5 times more likely to be uninsured than white patients, which could make treatment with donanemab inaccessible given the overall cost of treatment," she added.

Donanemab is given by infusion once monthly. Its price is expected to be $28,000 a year, Rosenthal noted, while Leqembi's price is $26,500 annually.

More information

The U.S. Centers for Disease Control and Prevention has more on Alzheimer's disease.

SOURCES: Journal of the American Medical Association, July 17, 2023; Eli Lilly & Co, news release, July 17, 2023