LONDON – A study to prove the practical clinical utility of amyloid PET scanning appears to be doing just that: The knowledge of patients’ brain amyloid status changed clinical management for 68% of those who had the imaging done.

Interim results of the Imaging Dementia–Evidence for Amyloid Scanning (IDEAS) study far exceeded the 30% change rate that investigators hoped to see, Gil Rabinovici, MD, said at the Alzheimer’s Association International Conference. Not only did many patients receive a more suitable care plan, the scans actually changed diagnoses in three-quarters of those who tested positive, said Dr. Rabinovici of the University of California, San Francisco.

The interim results represent about 4,000 patients – less than a quarter of the projected 18,500 that will be enrolled. But they are very good news for investigators, who hope to eventually present a positive data package to the Centers for Medicare & Medicaid Services as a rationale to make amyloid PET scanning a fully covered service.

The U.S.-wide, open-label study is being conducted in Medicare beneficiaries who have been diagnosed with mild cognitive impairment (MCI) or dementia of uncertain cause. Its two goals are to show that amyloid PET imaging affects a patient’s care plan within 3 months of the scan and to show an impact on major medical outcomes 12 months later. In diagnostically uncertain cases, investigators theorized, amyloid PET imaging would lead to significant changes in patient management, which would then translate into improved medical outcomes.

At the meeting, Dr. Rabinovici discussed the preplanned interim analysis of 3-month care plan changes. After the scan was completed, physicians related the results to patients and recommended any appropriate management changes. At the 90-day post-scan visit, physicians documented how any changes had been implemented. Data on the 12-month outcomes have not been announced on any portion of the cohort.

The patients were a mean of 76 years old; 64% had a diagnosis of MCI and 36% a diagnosis of dementia. Alzheimer’s disease was the suspected etiology in 74% of the MCI group and in 80% of the dementia group. About one-third of MCI patients and two-thirds of dementia patients were taking Alzheimer’s medications at enrollment.

The scans were positive in 54% of the MCI patients and in 70% of dementia patients. In amyloid-positive patients, the rate of Alzheimer’s diagnosis increased from 78% to 85%. In amyloid-negative patients, the rate of Alzheimer’s diagnosis decreased from 73% to 14%.

More than two-thirds of patients in both groups experienced a change in management after the scans were read. Changes in Alzheimer’s drugs occurred in 48% of both groups, while changes in non-Alzheimer’s drugs occurred in 36% of the MCI group and 32% of the dementia group. In amyloid-positive patients, use of Alzheimer’s drugs increased from 51% to 84%. In amyloid-negative patients, the use of Alzheimer’s drugs decreased from 39% to 31%.

Patient counseling also changed in 24% of the MCI group and 16% of the dementia group.

Dr. Rabinovici was cautiously optimistic about the interim results. “The study has two aims, and Medicare has made it clear that we need to complete both before they will consider covering the scans. I hope they understand that these changes in management are incredibly important, but they also want to see that they result in improved outcomes. That will take a year from when we enroll our last patient.”

Although the study is designed to show change in clinical outcomes, it’s also changing something less tangible, but no less important: patients’ understanding of their situation.

“We may be looking at objective changes in management, but we are also seeing that patients really want to know what’s going on in their brain, what the cause of their cognitive impairment is. They don’t want to be told that it’s normal aging, because they know it isn’t. There is a real value to getting that diagnosis, even if it’s the bad news that there are amyloid plaques in the brain. It leads to a clear plan in terms of what drugs to use, the possibility of enrolling in clinical trials, and getting some clarity about what’s going on. A lot of times, the certainty is better than the uncertainty.”

As of June, IDEAS had recruited 12,484 patients and completed 11,712 amyloid PET scans. Dr. Rabinovici hopes the recruitment will be completed by late this year, or early 2018.

IDEAS is being funded by the Centers for Medicare & Medicaid Services, Avid Radiopharmaceuticals/Eli Lilly, GE Healthcare, Piramal Imaging, the Alzheimer’s Association, and the American College of Radiology. Dr. Rabinovici has received honoraria or consulting fees from Eisai, Genentech, Lundbeck, Merck, Putnam, and Roche.

msullivan@frontlinemedcom.com

On Twitter @alz_gal

Amyloid PET imaging impacts diagnoses, management for those with MCI and dementia