Kozo Daniel, Ross Matt W, Jarrah Justin, Barrett Michael, Harney Rebecca L, Courtney Jodi B, Baburina Irina, Holleran Julianne L, Beumer Jan H, Peters Godefridus J, Honeywell Richard J, Salamone Salvatore J
*Saladax Biomedical, Inc., Bethlehem, Pennsylvania;†Cancer Therapeutics Program, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania;‡Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania; and§Department of Medical Oncology, VU University Medical Center, Amsterdam, the Netherlands.
Ther Drug Monit. 2017 Jun;39(3):235-242. doi: 10.1097/FTD.0000000000000402.
Gemcitabine (2',2'-difluoro-2'-deoxycytidine) is a nucleoside analog used as a single agent and in combination regimens for the treatment of a variety of solid tumors. Several studies have shown a relationship between gemcitabine peak plasma concentration (Cmax) and hematological toxicity. An immunoassay for gemcitabine in plasma was developed and validated to facilitate therapeutic drug monitoring (TDM) by providing an economical, robust method for automated chemistry analyzers.
A monoclonal antibody was coated on nanoparticles to develop a homogenous agglutination inhibition assay. To prevent ex vivo degradation of gemcitabine in blood, tetrahydrouridine was used as a sample stabilizer. Validation was conducted for precision, recovery, cross-reactivity, and linearity on a Beckman Coulter AU480. Verification was performed on an AU5800 in a hospital laboratory. A method comparison was performed with (LC-MS/MS) liquid chromatography tandem mass spectrometry using clinical samples. Selectivity was demonstrated by testing cross-reactivity of the major metabolite, 2',2'-difluorodeoxyuridine.
Coefficients of variation for repeatability and within-laboratory precision were <8%. The deviation between measured and assigned values was <3%. Linear range was from 0.40 to 33.02 μ/mL (1.5-125.5 μM). Correlation with validated LC-MS/MS methods was R = 0.977. The assay was specific for gemcitabine: there was no cross-reactivity to 2',2'-difluorodeoxyuridine, chemotherapeutics, concomitant, or common medications tested. Tetrahydrouridine was packaged in single-use syringes. Gemcitabine stability in whole blood was extended to 8 hours (at room temperature) and in plasma to 8 days (2-8°C).
The assay demonstrated the selectivity, test range, precision, and linearity to perform reliable measurements of gemcitabine in plasma. The addition of stabilizer improved the sample handling. Using general clinical chemistry analyzers, gemcitabine could be measured for TDM.
吉西他滨（2'，2'-二氟-2'-脱氧胞苷）是一种核苷类似物，可作为单一药物或联合用药方案用于治疗多种实体瘤。多项研究表明吉西他滨的血浆峰浓度（Cmax）与血液学毒性之间存在关联。为通过为自动化学分析仪提供一种经济、可靠的方法来促进治疗药物监测（TDM），开发并验证了一种血浆中吉西他滨的免疫测定法。
将单克隆抗体包被在纳米颗粒上，开发一种均相凝集抑制测定法。为防止吉西他滨在血液中离体降解，使用四氢尿苷作为样品稳定剂。在贝克曼库尔特AU480上进行精密度、回收率、交叉反应性和线性的验证。在医院实验室的AU5800上进行验证。使用临床样本与（LC-MS/MS）液相色谱串联质谱法进行方法比较。通过测试主要代谢物2'，2'-二氟脱氧尿苷的交叉反应性来证明选择性。
重复性和实验室内精密度的变异系数<8%。测量值与指定值之间的偏差<3%。线性范围为0.40至33.02μ/mL（1.5 - 125.5μM）。与经过验证的LC-MS/MS方法的相关性为R = 0.977。该测定法对吉西他滨具有特异性：对测试的2'，2'-二氟脱氧尿苷、化疗药物、伴随药物或常用药物无交叉反应性。四氢尿苷包装在一次性注射器中。全血中吉西他滨的稳定性延长至8小时（室温），血浆中延长至8天（2 - 8°C）。
该测定法证明了其选择性、测试范围、精密度和线性，可对血浆中的吉西他滨进行可靠测量。稳定剂的添加改善了样品处理。使用普通临床化学分析仪，可对吉西他滨进行TDM测量。
