The drug, Kisunla, made by Eli Lilly, is the latest in a new class of treatments that could modestly slow cognitive decline in initial stages of the disease but also carry safety risks.

The Food and Drug Administration on Tuesday approved a new drug for Alzheimer’s disease, the latest in a novel class of treatments that has been greeted with hope, disappointment and skepticism.

The drug, donanemab, to be sold under the brand name Kisunla, was shown in studies to modestly slow the pace of cognitive decline in early stages of the disease. It also had significant safety risks, including swelling and bleeding in the brain.

Kisunla, made by Eli Lilly, is similar to another drug, Leqembi, approved last year. Both are intravenous infusions that attack a protein involved in Alzheimer’s, and both can slow the unfolding of dementia by several months. Both also carry similar safety risks. Leqembi, made by Eisai and Biogen, is given every two weeks; Kisunla is given monthly.

Kisunla has a significant difference that may appeal to patients, doctors and insurers: Lilly says patients can stop the drug after it clears the protein, amyloid, which clumps into plaques in the brains of people with Alzheimer’s.

“Once you’ve removed the target that you’re going after, you then can stop dosing,” said Anne White, an executive vice president of Lilly and president of its neuroscience division. She said that this could reduce the overall cost and inconvenience of the treatment as well as the risk of side effects.

The company said that 17 percent of patients receiving donanemab in the 18-month-long clinical trial were able to discontinue the drug at six months, 47 percent stopped within a year and 69 percent stopped within 18 months. Their cognitive decline continued to slow even after they stopped. The company is evaluating how long that slowing will continue past the duration of the trial, said Dr. John Sims, a medical director at Lilly.

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