The Food and Drug Administration on Tuesday approved a new Alzheimer’s disease drug from Eli Lilly, several weeks after a panel of independent experts unanimously recommended its clearance.

The drug, which Lilly will sell as Kisunla, is designed to slow Alzheimer’s progression by clearing from the brain a toxic, sticky protein called amyloid that scientists have long seen as a root cause of the disease. It’s the third of its kind to reach market, following similar medicines from Eisai and Biogen.

In approving Kisunla, the FDA OK’d use in a roughly similar patient population as Eisai and Biogen’s Leqembi. Labeling for the drug, also known as donanemab, recommends doctors start treatment in patients who have mild cognitive impairment or dementia due to Alzheimer’s, and who have confirmed amyloid pathology.

Agency reviewers had previously questioned whether treatment should be restricted to patients whose brains have deposits of another protein, tau, that Lilly used as a criteria for enrollment in Kisunla’s clinical trials.

Kisunla comes with a safety warning for the risk of an imaging abnormality called ARIA that’s usually asymptomatic, but is associated with brain bleeding and swelling that can become serious. The drug’s label also asks doctors to test for a genetic profile that’s linked to higher rates of ARIA. The warning is similar to that of Leqembi.

Lilly will charge just under $700 per vial of Kisunla, which, if a patient continues treatment for one year, works out to about $32,000 annually. Eisai and Biogen set a price of $26,500 per year for Leqembi.

However, Lilly’s trials of Kisunla allowed treatment to be stopped if tests showed the drug successfully cleared amyloid from patients’ brains. That dosing strategy is noted in the FDA’s label and, if followed, would make Kisunla potentially less expensive in patients that reach minimal amyloid levels quickly.

“As a physician, I am encouraged by the potential to stop treatment, which could reduce out-of-pocket costs and infusion burden for eligible patients,” said Howard Fillit, co-founder and chief science officer of the Alzheimer’s Drug Discovery Foundation, in a statement provided by Lilly.

The FDA’s clearance of Kisunla is a traditional OK, rather than the accelerated approvals it initially granted to Biogen’s Aduhelm in 2021 and then to Leqembi two years later. Biogen later withdrew Aduhelm, while the FDA eventually converted Leqembi’s clearance to full.

Lilly had initially sought an accelerated approval for Kisunla, too, but the FDA rejected it in 2023 and asked for data on trial participants who had been exposed to more than one year of treatment.

Full approval should permit reimbursement for Kisunla under the federal Medicare program for the elderly and disabled, which covers most people with Alzheimer’s disease. Neither Aduhelm or Leqembi were eligible under accelerated approval. although Leqembi later gained coverage.

All three drugs are the product of many years of research that centered on the role played by amyloid. This protein clumps together to form toxic plaques that impair brain cells from communicating.

But the so-called amyloid hypothesis for Alzheimer’s has been hotly debated due to the repeated failure of earlier drugs to provide a benefit in testing. Aduhelm was the first to reach patients, but arrived shrouded in controversy due to shaky evidence and a high price tag that put off insurers.

The data backing Leqembi, meanwhile, was more straightforward. And with full FDA approval in place, Leqembi sales have ticked up, though not as much as Eisai and Biogen had initially hoped.

Wall Street analysts have debated which product, Leqembi or Kisunla, would hold an advantage commercially. Data suggest the former may be safer, while the latter is likely more convenient since it’s given every four weeks instead of every two. However, the drugs have not been tested directly against each other, making comparisons difficult.

In either case, investors expect Kisunla to become another blockbuster medicine in Lilly’s arsenal, adding to the success of the company’s diabetes and obesity drugs. Consensus among Wall Street analysts is that Kisunla will generate close to $5 billion in annual sales at its peak, according to the investment firm Jefferies.

Both drugs are recommended for use in patients with mild cognitive impairment or mild dementia, which could place greater emphasis on early disease detection.