Lewy body dementia is associated with a protein called alpha-synuclein that clumps together in the brain. But for many people with LBD, that isn’t the only thing going on. A large share also have amyloid plaques — the sticky protein buildup most associated with Alzheimer’s disease. Think of it like a house with both a leaky roof and faulty wiring: two separate problems in the same building, each causing damage on its own. Research suggests that people who have both kinds of brain changes tend to decline faster than people who have just one. TRAILBLAZER-ALZ 7 is testing whether treating one of those problems — the amyloid — can slow that decline.

What is this study about?

This research study is testing a drug called donanemab in people who have early memory and thinking problems associated with both alpha-synuclein and amyloid. Donanemab is designed to clear amyloid plaques out of the brain. Researchers want to know whether removing those plaques slows down changes in thinking — how a person learns, remembers, pays attention, and makes decisions — and changes in the ability to handle everyday activities. The drug does not remove alpha-synuclein.

Donanemab, sold under the brand name Kisunla, is already approved by the U.S. Food and Drug Administration to treat adults with early symptomatic Alzheimer’s disease, meaning people with mild cognitive impairment or the mild dementia stage of Alzheimer’s who have confirmed amyloid in the brain. It is not approved for people with Lewy body disease. TRAILBLAZER-ALZ 7 is a Phase 2 study, which means researchers are still learning how well the drug works and how safe it is for this particular group of people.

What is involved?

Taking part in this study lasts about a year and a half from start to finish. Here is what you can expect:

• Screening period (up to 120 days): This period determines whether the study is a fit for you. It happens in stages, starting with a blood test and moving on to memory and thinking tests, brain imaging, an MRI, and a spinal fluid test done through a lumbar puncture (sometimes called a spinal tap). The spinal fluid test is how the study team confirms whether both alpha-synuclein and amyloid are present.
• Treatment period (48 weeks): Participants are randomly assigned — like a coin flip — to receive either donanemab or a placebo. Neither you, your study partner, nor your study doctor will know which one you are getting. The medicine is given through an IV about once every four weeks.
• Follow-up period (up to 12 weeks after the final dose): The study team continues to check on participants after treatment ends.
• Assessments: Throughout the study, participants complete tests of memory, thinking, movement, mood, and daily activities. Participants also have MRI scans and brain imaging to track how the treatment is working and to monitor safety.
• Study partner role: A study partner is required. This is someone who is in frequent contact with you, knows your day-to-day abilities well, and can come to visits.
• Costs covered: There is no cost to participate. All study-related care is provided at no charge, and reimbursement for travel and other study-related expenses may be available.

Study doctors and staff will closely monitor participants and answer any questions that may arise throughout this research project.

Who can participate?

A person may be able to participate in this study if they:

• Are 55 to 85 years old
• Have had gradually worsening memory or thinking problems for at least 6 months
• Have at least one core feature of dementia with Lewy bodies (special note – this includes people with Parkinson’s disease): alertness and attention that comes and goes, recurring visual hallucinations, acting out dreams during sleep (REM sleep behavior disorder), or Parkinson’s-like movement changes such as slowness, stiffness, or tremor at rest
• Have mild cognitive impairment rather than dementia — meaning memory and thinking changes are noticeable, but you are still largely managing on your own
• Have biomarker evidence of both alpha-synuclein and amyloid in the brain
• Have a study partner who can come to visits and help with study participation

You may still be able to join if you are taking medication for memory, LBD, or Parkinson’s symptoms, as long as your dose has been steady for at least 30 days.

Note: You do not need to know whether you have amyloid or alpha-synuclein in your brain before you contact a study site. Even if you have had brain scans or other tests before, the study team will do its own testing during screening to answer that question.

Some things may prevent someone from joining, including having already been treated with another drug that targets amyloid, another neurological condition that affects thinking, certain findings on a brain MRI, or a medical reason you cannot have an MRI, a brain scan, or a lumbar puncture. A study doctor can explain this in more detail.

Study Sites

Additional locations are expected to open during the course of the study. The study is also enrolling volunteers outside the United States.

Study Funder/Sponsor

This study is funded and sponsored by Eli Lilly and Company.

Still have questions?

To learn more about the study or find out whether you may be eligible, call the study site nearest you using the phone numbers listed above. You can also call the study sponsor’s information line at 1-877-CTLILLY (1-877-285-4559), Monday through Friday, 8 AM to 8 PM Eastern time.

This study is registered on ClinicalTrials.gov as NCT07589595.