Pharmacokinetics, Pharmacodynamics and Drug Metabolism, Merck & Co., Inc., Kenilworth, New Jersey, USA.
Process Chemistry, Merck & Co., Inc., Kenilworth, New Jersey, USA.
AAPS J. 2022 Apr 6;24(3):52. doi: 10.1208/s12248-022-00683-4.
In-clinic dried blood spot (DBS) pharmacokinetic (PK) sampling was incorporated into two phase 3 studies of verubecestat for Alzheimer's disease (EPOCH [NCT01739348] and APECS [NCT01953601]), as a potential alternative to plasma PK sampling for improved logistical feasibility and decreased blood volume burden. However, an interim PK analysis revealed verubecestat concentrations in DBS samples declined with time to assay in both trials. An investigation revealed wide variation in implementation practices for DBS sample handling procedures resulting in insufficient desiccation which caused verubecestat instability. High-resolution mass spectrometry evaluations of stressed and aged verubecestat DBS samples revealed the presence of two hydrolysis degradants. To minimize instability, new DBS handling procedures were implemented that provided additional desiccant and minimized the time to analysis. Both verubecestat hydrolysis products were previously discovered and synthesized during active pharmaceutical ingredient stability characterization. A liquid chromatography-mass spectrometry assay to quantitate the dominant verubecestat degradant in DBS samples was developed and validated. The application of this method to stressed and aged verubecestat DBS samples confirmed that degradant concentrations accounted for the observed decreases in the verubecestat concentration. Furthermore, after increasing desiccant amounts, degradant concentrations accounted for approximately 7% of the verubecestat concentration in DBS clinical samples, indicating that issues with sample handling were minimized with new storage and shipping conditions. This case study illustrates the challenges with employing new sampling techniques in large, global trials, and the importance of anticipating and mitigating implementation risks.
在两项针对阿尔茨海默病的 3 期研究（EPOCH [NCT01739348]和 APECS [NCT01953601]）中，采用了在诊室内进行干血斑（DBS）药代动力学（PK）采样，作为替代血浆 PK 采样的潜在方法，以提高采样的可行性并减少采血负担。然而，中期 PK 分析显示，在两项试验中，DBS 样本中的 verubecestat 浓度随检测时间的推移而下降。一项调查显示，DBS 样本处理程序的实施存在广泛差异，导致干燥不充分，从而导致 verubecestat 不稳定。对受胁迫和老化的 verubecestat DBS 样本进行高分辨率质谱评估发现存在两种水解降解产物。为了最大限度地减少不稳定性，实施了新的 DBS 处理程序，提供了额外的干燥剂并最大限度地减少了分析时间。两种 verubecestat 水解产物均在活性药物成分稳定性特征研究期间被发现并合成。开发并验证了一种用于定量 DBS 样本中主要 verubecestat 降解产物的液相色谱-质谱法检测法。该方法应用于受胁迫和老化的 verubecestat DBS 样本，证实降解产物浓度解释了 verubecestat 浓度的观察下降。此外，在增加干燥剂用量后，降解产物浓度占 DBS 临床样本中 verubecestat 浓度的约 7%，表明新的储存和运输条件最大限度地减少了样本处理问题。该案例研究说明了在大型全球试验中采用新采样技术所面临的挑战，以及预测和减轻实施风险的重要性。
