A second drug that modestly slows the progression of Alzheimer’s disease could be approved by the end of this year, manufacturer Eli Lilly said Monday.

In a statement, Lilly said it applied to the Food and Drug Administration (FDA) for traditional approval last quarter and expects the agency to act by the end of the year. 

According to Lilly, its monoclonal antibody called donanemab slowed Alzheimer’s disease progression by 35 percent relative to placebo in an 18-month clinical trial that enrolled 1,700 patients with early-stage disease. In practical terms, that translated to delaying progression by about four months.

Study participants at the earliest stage of disease had an even greater benefit, with 60 percent slowing of decline compared to placebo, the company said.

The company shared the results at the 2023 Alzheimer’s Association International Conference and simultaneously published them in the Journal of the American Medical Association (JAMA).

Donanemab would be the second successful Alzheimer’s drug on the market after the FDA earlier this month approved Biogen and Eisai’s Leqembi. The new data from Lilly is similar to the data cited by the FDA when it approved Leqembi. 

Neither drug is a cure, but they could expand the treatment options for people with early-stage Alzheimer’s. 

More than 6 million people in the United States are diagnosed with Alzheimer’s, and that number is expected to rise as the population ages. There are about 1 million people with early-stage disease who could benefit most from the drug.

Both treatments are monoclonal antibodies that target a brain plaque called amyloid. The drugs are administered by intravenous infusion — Leqembi every two weeks and donanemab every four.

Both significantly reduce the levels of plaque, but there remain questions about the clinical significance and degree of benefit.

In one editorial in JAMA accompanying the trial results, the authors raised concerns about racial inequities in treatment, especially because minority groups are typically diagnosed at later disease stages. 

Similar to the trial for Leqembi, the trial for donanemab did not include many people who identified as minorities; of the U.S.-based participants, 96 percent were white and 94 percent were non-Hispanic. Lilly said fewer people who were Black or Hispanic had positive scans confirming they had both amyloid and tau proteins required to join the study. 

That means it’s difficult to assess the safety or efficacy among American Indian or Alaska Native, Asian, Black, or Hispanic populations. 

And there are serious risks associated with the treatment.

Three deaths were determined to be drug-related among participants who developed serious brain bleeding or swelling, called amyloid-related imaging abnormalities (ARIA). Donanemab had an ARIA rate of 37 percent, compared with 15 percent for patients on a placebo.

“Given the wide availability of these drugs following US Food and Drug Administration approval and the disproportionate burden of cognitive impairment and dementia due to Alzheimer disease in many of these groups, it is critical that clinicians, patients, and families understand the limits of what is known,” Jennifer Manly, of Columbia University Irving Medical Center, and Kacie Deters, of the University of California, Los Angeles, wrote in the editorial.

“Clinicians and the public will need to weigh the potential benefit of treatment (delay of progression of about 4 months on average) with the financial and quality-of-life costs of infusions, MRI monitoring, and risk of amyloid-related imaging abnormalities and brain volume loss,” they added. 

Lilly did not disclose how it would price donanemab following a potential approval. Leqembi will cost $26,500 per year. 

The Centers for Medicare and Medicaid Services has said Medicare will cover Alzheimer’s drugs — as long as they receive full FDA approval and companies gather data on how the drugs work in the real world.

Medicare patients could also face thousands of dollars a year in co-insurance. Without supplemental coverage, enrollees are responsible for 20 percent of the cost after meeting a deductible. 

Patients may also be responsible for potentially tens of thousands of dollars of additional costs beyond the drug itself. It’s unclear if Medicare will pay for the cost of the medical visit or the regular brain scans needed to monitor a patient’s progress.