Teunissen Charlotte E, Kolster Rachel, Triana-Baltzer Gallen, Janelidze Shorena, Zetterberg Henrik, Kolb Hartmuth C
Department of Clinical Chemistry, Amsterdam University Medical Centers, Amsterdam, the Netherlands.
Janssen Global Medical Affairs, Titusville, New Jersey, USA.
Alzheimers Dement. 2025 Jan;21(1):e14397. doi: 10.1002/alz.14397. Epub 2024 Dec 3.
The revised biomarker framework for diagnosis and staging of Alzheimer's disease (AD) relies on amyloid beta (Aβ) and tau pathologies as core markers, and markers for adjacent pathophysiology, such as neurodegeneration and inflammation. Many of the core fluid biomarkers are phosphorylated tau (p-tau) fragments, with p-tau217 showing a prominent association with Aβ and tau. While positron emission tomography (PET) imaging is well established, plasma p-tau assays are newer and likely to reduce the use of expensive, and less accessible cerebrospinal fluid and PET imaging tests, thereby promoting wider access to AD screening. There is a need for greater understanding of how the various plasma p-tau species reflect different pathological processes of AD and how different immunoassays perform. This review surveys the available immunoassays and highlights their strengths and limitations in different contexts of use. Assays need to be standardized to maximize their impact on AD clinical research, and patient diagnosis and management. HIGHLIGHTS: Different plasma phosphorylated tau (p-tau) species reflect different pathological processes of Alzheimer's disease (AD), with p-tau231 showing the greatest association with the earliest increases in brain amyloid beta (Aβ) accumulation, while p-tau217 shows greater association with both brain Aβ and early tau pathology, and other p-tau and tau fragment species show greater association with later stages of brain tau pathology. Plasma p-tau217 has proven to be an excellent biomarker for AD pathology due to its close association with both brain Aβ and tau pathology, as well as its large dynamic range. Many different assays with varying performance exist for the same p-tau species, with mass spectrometry assays performing uniformly well, and several immunoassays achieving comparable performance. "Round robin" head-to-head studies have been performed to compare different assays for several key plasma biomarkers, including p-tau181 and p-tau217, but additional head-to-head studies are needed, especially for new analytes and for measuring performance in diverse populations. Plasma immunoassays have the potential to increase accessibility of early diagnostic testing for a broad population, including diverse historically under-represented and under-served populations, due to the potential to be implemented globally, including in primary care settings; however, further research is needed to validate the optimal cutoffs for each assay for real-world clinical usage. Eventually, clinical implementation of a two-step workflow may allow standalone use of plasma testing in certain contexts, minimizing the need for confirmation with costly and less accessible cerebrospinal fluid/positron emission tomography testing.
修订后的阿尔茨海默病（AD）诊断和分期生物标志物框架依赖于β淀粉样蛋白（Aβ）和tau病理作为核心标志物，以及相邻病理生理学的标志物，如神经变性和炎症。许多核心体液生物标志物是磷酸化tau（p-tau）片段，其中p-tau217与Aβ和tau显著相关。虽然正电子发射断层扫描（PET）成像已得到广泛应用，但血浆p-tau检测是较新的技术，可能会减少昂贵且难以获取的脑脊液和PET成像检测的使用，从而促进AD筛查的更广泛普及。需要更深入了解各种血浆p-tau种类如何反映AD的不同病理过程以及不同免疫测定的性能。本综述调查了现有的免疫测定方法，并强调了它们在不同使用背景下的优势和局限性。测定方法需要标准化，以最大限度地提高其对AD临床研究以及患者诊断和管理的影响。要点：不同的血浆磷酸化tau（p-tau）种类反映了阿尔茨海默病（AD）的不同病理过程，p-tau231与脑内β淀粉样蛋白（Aβ）积累最早增加的关联最大，而p-tau217与脑内Aβ和早期tau病理的关联更大，其他p-tau和tau片段种类与脑内tau病理的后期阶段关联更大。血浆p-tau217已被证明是AD病理的优秀生物标志物，因为它与脑内Aβ和tau病理密切相关，且动态范围大。对于同一p-tau种类存在许多性能各异的不同检测方法，质谱检测方法表现一致良好，一些免疫测定方法也达到了可比的性能。已经进行了“循环”直接比较研究，以比较几种关键血浆生物标志物（包括p-tau181和p-tau217）的不同检测方法，但还需要更多的直接比较研究，特别是针对新分析物以及在不同人群中测量性能的研究。血浆免疫测定有潜力提高广大人群（包括历史上代表性不足和服务不足的不同人群）早期诊断检测的可及性，因为其有可能在全球范围内实施，包括在初级保健机构；然而，需要进一步研究以验证每种检测方法在实际临床应用中的最佳临界值。最终，两步工作流程的临床应用可能允许在某些情况下单独使用血浆检测，最大限度减少使用昂贵且难以获取的脑脊液/正电子发射断层扫描检测进行确认的需求。
