Eastwood Stephanie M, Meyer Matthew R, Kirmess Kristopher M, Wente-Roth Traci L, Irvin Faith, Holubasch Mary S, Verghese Philip B, West Tim, Braunstein Joel B, Yarasheski Kevin E, Contois John H
C2N Diagnostics, 4340 Duncan Avenue, Suite 110, Saint Louis, MO 63110, USA.
Diagnostics (Basel). 2024 Aug 10;14(16):1739. doi: 10.3390/diagnostics14161739.
Alzheimer's disease (AD) is a progressive irreversible neurodegenerative disorder that represents a major global public health concern. Traditionally, AD is diagnosed using cerebrospinal fluid biomarker analysis or brain imaging modalities. Recently, less burdensome, more widely available blood biomarker (BBM) assays for amyloid-beta (Aβ42/40) and phosphorylated-tau concentrations have been found to accurately identify the presence/absence of brain amyloid plaques and tau tangles and have helped to streamline AD diagnosis. However, few BBMs have been rigorously analytically validated. Herein, we report the analytical validation of a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) multiplex method for quantifying plasma phosphorylated-tau217 (p-tau217) and non-phosphorylated-tau217 (np-tau217) peptide concentrations. We combined the p-tau217/np-tau217 concentrations ratio (%p-tau217) and the previously validated LC-MS/MS multiplex assay for plasma Aβ42/40 into a new multianalyte assay with algorithmic analysis (MAAA; PrecivityAD2™ test) that identifies brain amyloid status based on brain amyloid positron emission tomography. We found (a) the %p-tau217 assay is precise, accurate, sensitive, and linear over a wide analytical measurement range, and free from carryover and interference; (b) the pre-analytical specimen collection, processing, storage, and shipping conditions that maintain plasma tau peptide stability; and (c) using the measured analytical imprecision for plasma Aβ42/40 and p-tau217/np-tau217 levels in a worst-case scenario model, the PrecivityAD2 test algorithm for amyloid pathology classification changed for only 3.5% of participants from brain amyloid positive to negative, or from negative to positive. The plasma sample preparation and LC-MS/MS methods underlying the PrecivityAD2 test are suitable for use in the clinical laboratory and valid for the test's intended purpose: to aid in the diagnostic evaluation of individuals aged 55 and older with signs or symptoms of mild cognitive impairment or dementia.
阿尔茨海默病（AD）是一种进行性不可逆的神经退行性疾病，是全球主要的公共卫生问题。传统上，AD通过脑脊液生物标志物分析或脑成像方式进行诊断。最近，人们发现用于检测淀粉样β蛋白（Aβ42/40）和磷酸化tau蛋白浓度的、负担较小且更易获得的血液生物标志物（BBM）检测方法能够准确识别脑淀粉样斑块和tau缠结的存在与否，并有助于简化AD的诊断。然而，很少有BBM经过严格的分析验证。在此，我们报告了一种用于定量血浆磷酸化tau217（p-tau217）和非磷酸化tau217（np-tau217）肽浓度的新型液相色谱-串联质谱（LC-MS/MS）多重方法的分析验证。我们将p-tau217/np-tau217浓度比（%p-tau217）与先前验证的用于血浆Aβ42/40的LC-MS/MS多重检测方法相结合，形成了一种新的具有算法分析的多分析物检测方法（MAAA；PrecivityAD2™检测），该方法基于脑淀粉样正电子发射断层扫描来识别脑淀粉样状态。我们发现：（a）%p-tau217检测在广泛的分析测量范围内具有精密度高、准确性高、灵敏度高和线性良好的特点，且无残留和干扰；（b）分析前的标本采集、处理、储存和运输条件能够维持血浆tau肽的稳定性；（c）在最坏情况模型中，使用血浆Aβ42/40和p-tau217/np-tau217水平的测量分析不精密度，PrecivityAD2检测算法用于淀粉样病理分类时，只有3.5%的参与者从脑淀粉样阳性变为阴性，或从阴性变为阳性。PrecivityAD2检测所基于的血浆样品制备和LC-MS/MS方法适用于临床实验室，并且对于该检测的预期目的是有效的：帮助对55岁及以上有轻度认知障碍或痴呆体征或症状的个体进行诊断评估。
