Advances in Alzheimer Disease Screening and Antibody Therapy at AAIC 2025: Eric Siemers, MD

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“We found in the phase 1 study that when we did get PET scans on patients, about 60% of the time they were negative. In other words, they actually did not have Alzheimer pathology. What we found by using this blood test in our phase 2 study is that the rate of negative PET scans was only 17%, so it improved dramatically from over 60% negative to only 17% negative.”

Acumen Pharmaceuticals recently presented pivotal results from 2 poster presentations at the 2025 Alzheimer’s Association International Conference, held July 27-30, in Toronto, Canada. The first, demonstrated that implementing a blood-based pTau217 screening assay reduced clinical trial screening costs by approximately 40%, using the company’s phase 2 ALTITUDE-AD study (NCT06335173) of sabirnetug in early Alzheimer disease (AD) as the input example. The company noted that this 2-part screening process using plasma pTau217 not only cut costs but also improved trial efficiency by reducing unnecessary amyloid PET scans and lumbar punctures.

In the second poster, biochemical data underscored sabirnetug’s high selectivity for toxic β-amyloid oligomers, which was implicated as early drivers of AD pathology. Surface plasmon resonance testing revealed that sabirnetug binds β-amyloid oligomers with an 8750-fold selectivity over abundant monomeric β-amyloid forms, outperforming other monoclonal antibodies such as lecanemab (Leqembi; Eisai) and aducanumab (Aduhelm; Eisai/Biogen). The company noted that this selectivity may support sabirnetug’s targeted mechanism of action, aiming to slow neurodegeneration and synapse loss in early AD.

During AAIC 2025, Eric Siemers, MD, chief medical officer at Acumen Pharmaceuticals, spoke with NeurologyLive^® to elaborate on these findings, providing deeper insights into the company’s innovative approaches. In the conversation, he emphasized how the blood-based p-tau 217 biomarker screening also holds promise for wider clinical adoption to better identify patients needing further diagnostic evaluation. Additionally, Siemers discussed the biochemical profile of sabirnetug, highlighting its selectivity for β-amyloid oligomers compared with other antibodies. Furthermore, he underscored the growing importance of blood-based biomarkers in managing patients with cognitive impairment.

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REFERENCES
1. Acumen Pharmaceuticals Presents Studies Showing the Utility of a pTau217 Assay in Screening for a Phase 2 Alzheimer’s Disease Trial and Validates Sabirnetug Oligomer-Selectivity, at the Alzheimer’s Association International Conference (AAIC) 2025. News Release. Acumen Pharmaceuticals. Published July 28, 2025. Accessed August 12, 2025. https://investors.acumenpharm.com/news-releases/news-release-details/acumen-pharmaceuticals-presents-studies-showing-utility-ptau217