New Blood Biomarkers Show Promise for Early Alzheimer’s Diagnosis

Recent advancements in Alzheimer’s diagnosis may soon allow for earlier identification of the disease through blood testing. Particularly, a protein known as phosphorylated tau 217, or P-tau217, is emerging as a promising blood-based biomarker. This discussion includes insights from Nino Sireci, Senior Vice President of Clinical Biomarkers and Diagnostics at Eli Lilly, who has been actively involved in this research area.

Currently, the diagnostic pathway for Alzheimer’s disease typically involves costly imaging techniques, such as positron emission tomography (PET) scans, which identify amyloid and tau deposits in the brain. However, Sireci highlights that diagnostic methods have evolved significantly in recent years. Previously relying on symptomatology and post-mortem examinations, the field is now transitioning towards utilising blood biomarkers that could simplify the diagnostic process.

Sireci noted, "For the first time, we could actually see the pathology in vivo," but emphasised the need for a more accessible solution. The introduction of P-tau217 is seen as a pivotal development, with the U.S. Food and Drug Administration (FDA) recently clearing two P-tau217 blood tests to assist in identifying Alzheimer’s pathology.

Furthermore, Eli Lilly is collaborating with Roche Diagnostics to refine these tests. Currently, there are two FDA-cleared tests offered by Fujirebio and Roche, while other companies are also exploring the potential for similar tests targeting P-tau217.

What distinguishes P-tau217 from other markers is its efficacy in both confirming and ruling out Alzheimer’s disease. Sireci explained that the utility of a biomarker could be summarised in two key functions: confirming disease presence (rule in) and ensuring absence of disease (rule out). P-tau217 performs effectively in both scenarios, contributing to increased diagnostic confidence.

In conjunction with advancements in biomarker testing, two significant studies further aim to provide clarity on the P-tau217 profile. The ANCHOR-AD study will focus on cognitively unimpaired patients with elevated P-tau levels to understand their progression over time. It aims to gather diverse patient profiles across different ethnicities, which is believed to enhance the understanding of P-tau’s implications.

The TEACH-AD study, another initiative led by Eli Lilly, will investigate how doctors respond to P-tau217 test results in both primary and secondary care settings, particularly when patients report subtle cognitive concerns. These studies seek to determine the practical applications of the blood test in clinical settings.

Moreover, recent research published in the Lancet Neurology suggests that combining P-tau217 measurements with genetic information, specifically the apolipoprotein E (APOE) genotype, could offer improved predictive capabilities for cognitive impairment. Analysis of data from multiple cohorts, comprising over 8,500 participants, revealed that higher P-tau217 concentrations indicated a greater likelihood of cognitive decline, particularly in APOE-ε4 allele carriers.

The study demonstrated that individuals possessing higher levels of P-tau217 may experience varying clinical outcomes based on their genetic profile, suggesting a pathway for more tailored monitoring and intervention strategies.

Despite these advancements, experts caution against the routine testing of asymptomatic individuals. The researchers highlighted that the findings require further validation across varied populations and that cognitive impairment was assessed inclusively rather than solely for Alzheimer’s disease.

In conclusion, while further research is needed, integrating P-tau217 and genetic risk factors could mark a significant shift towards more personalised and early intervention strategies in Alzheimer’s disease diagnosis and treatment, paving the way for better patient outcomes in the future.