American drugmaker Eli Lilly has some good news about its experimental Alzheimer’s treatment, donanemab.
In a press release announcing the results of a recent trial, Eli Lilly revealed that the drug was successful in halting the clinical progression of the disease in almost half the participants (47%). The drug slowed the rate of cognitive decline by 35% compared to a placebo. The 18-month trial was conducted on nearly 1,200 patients with early stage Alzheimer’s disease presenting mild cognitive impairment and mild dementia.
Donanemab is an antibody that identifies and destroys amyloid beta proteins, excess abnormal proteins that bind together to create brain plaques. Although the specific cause of Alzheimer’s—and of the excess abnormal proteins—is still unknown, it’s believed that the plaques slow down the functioning of the brain, causing advancement of the disease.
In the trial, patients had to take donanemab for up to 18 months, or until they reached the desired plaque clearance level. For nearly half the participants, this occurred within a year. The fact that removing the plaques resulted in halted disease progression also supports the link between amyloid beta proteins buildup and Alzheimer’s.
The results were encouraging, although there are safety concerns: At least two of the trial participants died following brain swelling caused by the treatment.
The difference between Aduhelm, Leqembi, and donanemab
Eli Lilly hopes to apply for donanemab’s approval from the Food and Drug Administration (FDA) this quarter. It was denied accelerated approval earlier this year due to the limited size and duration of the trial. If approved, donanemab would become the third new drug on the market for Alzheimer’s in about three years. The first, Biogen’s Aduhelm (aducanumab), was approved in June 2020 despite persistent concerns about it being associated with the risk of potentially deadly brain swelling.
Brain swelling is also a risk associated with Eisai’s and Biogen’s Leqembi (lecanemab), which obtained accelerated FDA approval this past January. The drug slowed progression of Alzheimer’s by 27%. Donanemab works in a similar way to Leqembi but can be taken for shorter periods of time. However, it has shown limited effects in patients with more advanced Alzheimer’s. Even if it earned rapid FDA approval, it’s likely both drugs would be viable in a market that is growing through better awareness and earlier diagnoses.
Eli Lilly’s stock jumped by 6% following the result’s announcement and is up 50% since the beginning of the year.