Amyloid and tau PET as key technologies for modern Alzheimer’s treatment

“Molecular imaging enables us to visualize functions and target structures using targeted tracers. This is vital for delivering precision medicine and thus tailoring treatment to the individual patient. Traditionally, the main focus of nuclear medicine has been on oncology. However, we are discovering more and more targets – particularly in neurology and cardiology – for which we are developing specialized tracers through basic research. Enormous progress is being made, particularly in the characterization and therapeutic monitoring of neurodegenerative diseases – above all in Alzheimer’s disease,” says Prof. Dr Matthias Brendel, Deputy Director of the Department of Nuclear Medicine at LMU Munich.

Up to 105,000 people with Alzheimer’s in Austria – PET scans provide certainty

In Austria alone, between 100,000 and 150,000 people are affected by dementia. Accounting for 60–70 per cent of all cases of dementia, Alzheimer’s disease is the most common form of dementia. “Using molecular imaging – more specifically, an amyloid PET scan – we can visualize the amyloid in the brain of a person with dementia and thus determine whether it is actually Alzheimer’s disease or another form of dementia. This is important because the new therapy using monoclonal antibodies against beta-amyloid – namely the drugs lecanemab and donanemab – can only be effective in cases of Alzheimer’s disease,” emphasizes Brendel. Traditional diagnostic tools such as blood biomarkers and cerebrospinal fluid biomarkers often leave a certain degree of uncertainty. It is therefore important to always carry out an amyloid PET scan for confirmation before starting treatment.

Amyloid PET scan crucial for determining treatment duration

The amyloid PET scan is also of great importance in determining how effective Alzheimer’s treatment is. “The amyloid PET scan shows at what point the amyloid level in the brain falls below the detection limit. In many cases, this is already the case after 12 months of taking donanemab, even though the treatment is generally designed to last 1.5 years. Once the amyloid has been cleared from the brain, the treatment has been successful and the drug can potentially be discontinued,” explains Brendel, emphasizing: “If we therefore assume that 60 to 70 per cent of treated patients can end their treatment earlier thanks to the amyloid PET scan, then the PET scan is also more than cost-effective.”

Innovative, highly effective amyloid antibody with shuttle mechanism in development

In addition to existing Alzheimer’s drugs, a new amyloid antibody is currently being developed which can cross the blood-brain barrier via its own shuttle mechanism. “This significantly increases the availability of the antibody in the brain and reduces side effects. Treatment can then be administered even more quickly – expectedly within three to four months – whilst minimizing side effects for patients. Here too, amyloid PET scanning will be required to ensure the treatment has been successfully completed, but we must, of course, await the conclusion of the regulatory trials,” adds the nuclear medicine specialist.

The mechanism of action of amyloid in the brain – slowing the progression of the disease by up to 30 per cent

In principle, amyloid-beta is a protein that occurs naturally in the brain. In the brains of Alzheimer’s patients, amyloid-beta accumulates between the brain cells, initially forming small clumps and later developing into large plaques. The biological process underlying Alzheimer’s disease thus begins years before the first symptoms become noticeable. “Whilst the tracers used in PET scans bind to the compact plaques and visualize them, the drugs act on the early aggregates and can thus slow the progression of the disease by up to 30 per cent at an early stage,” emphasizes Brendel. The earlier treatment can be started, the better. That is why the two new drugs, lecanemab and donanemab, are aimed at Alzheimer’s patients in the early stages, when the patient is at the stage of mild cognitive impairment or mild dementia.

Tau-PET – for predicting the course of the disease

In Alzheimer’s patients, the amyloid-beta protein, in combination with another protein called tau, disrupts communication between cells, causing the nerve cells of those affected to die off progressively. “That is why, at our clinic alone, more than 500 amyloid and tau PET scans are carried out each year to diagnose Alzheimer’s disease. Although there is not yet an approved drug that targets tau deposits, tau PET imaging is already of enormous importance. What makes Tau-PET special is that, using the tracer employed at the LMU Medical Centre, we also obtain a binding curve which allows us to determine whether there are amyloid-beta-associated tau deposits and to assess the extent of neuronal damage; this enables us to make accurate predictions regarding the progression of the disease and the likelihood of a positive response to treatment,” emphasizes Brendel. This is because studies show that patients with low levels of tau respond better to the new drugs than those with high levels of tau in the brain. “For me, therefore, amyloid PET is important for establishing a definitive diagnosis of Alzheimer’s in general. Tau PET has the greatest potential because it enables us to determine, with a high degree of certainty, who is particularly suitable for the therapies that are already available and who would benefit little or not at all from them,” explains the nuclear medicine specialist. Nuclear medicine therefore plays a key role in modern Alzheimer’s treatment.

Über die IAKW-AG und EANM

IAKW-AG (Internationales Amtssitz- und Konferenzzentrum Wien, Aktiengesellschaft) is responsible for the maintenance of the Vienna International Centre (VIC) and the operation of the Austria Center Vienna. With 21 halls, 134 meeting rooms and around 26,000 m² of exhibition space, the Austria Center Vienna is Austria’s largest conference centre and ranks among the leading players in the international conference industry. The European Association of Nuclear Medicine (EANM) is based in Vienna and is Europe’s largest non-profit medical organisation dedicated to nuclear medicine. Since its foundation in 1985, the EANM has been bringing together healthcare professionals, other medical societies, EU policy-makers and industry representatives to ensure that patients across Europe have easy access to nuclear medicine.

https://www.acv.at/de/
www.eanm.org