Abstract：
4β-Hydroxycholesterol (4β-HC) in plasma has been used as a biomarker to assess CYP3A drug-drug interaction (DDI) potential during drug development. However, due to the long half-life and narrow dynamic range of 4β-HC, its use has been limited to the identification of CYP3A inducers, but not CYP3A inhibitors. The formation of 1β-hydroxydeoxycholic acid (1β-OH DCA) from deoxycholic acid (DCA) is mediated by CYP3A, thus 1β-OH DCA can potentially serve as an alternative to 4β-HC for assessment of CYP3A DDI potential. To study this feasibility, we developed a sensitive liquid chromatography-tandem mass spectrometry method for the simultaneous quantitation of 1β-OH DCA and its glycine and taurine conjugates in human plasma with the lower limit of quantitation of 50 pg/ml, which enabled the quantitation of basal levels and further reduction. The method was applied to a DDI study to assess how 1β-OH DCA and its glycine and taurine conjugates would respond to CYP3A induction or inhibition. Rifampin induction resulted in an increase of 1β-OH DCA and its conjugates in plasma, with 6.8-, 7.8-, 8.3-, and 10.3-fold increases of area under the curve from the time of dosing to the last measurable concentration (AUCLST), area under the curve from the time of dosing to 24 hours (AUC24h), C max, and mean concentrations for total 1β-OH DCA (total of all three forms), respectively. Importantly, inhibition with itraconazole resulted in notable reduction of these biomarkers, with 84%, 85%, 82%, and 81% reductions of AUCLST, AUC24h, C max, and mean concentrations for total 1β-OH DCA, respectively. These preliminary data demonstrate for the first time that total 1β-OH DCA in plasma has the potential to serve as a biomarker for CYP3A DDI assessment in early clinical development and may provide key advantages over 4β-HC. SIGNIFICANCE STATEMENT: The authors have reported the use of total 1β-hydroxydeoxycholic acid (1β-OH DCA) (sum of 1β-OH DCA and its glycine and taurine conjugates) plasma exposure as a biomarker for CYP3A activity. Itraconazole inhibition led to an 81%-85% decrease of total 1β-OH DCA plasma exposures, whereas rifampin induction led to a 6.8- to 10.3-fold increase of total 1β-OH DCA plasma exposures. Using 1β-OH DCA exposures in plasma also provides the benefit of allowing pharmacokinetic and biomarker assessment using the same matrix.
摘要：
血浆中的4β-羟基胆固醇（4β-HC）已被用作生物标志物，以评估药物开发过程中CYP3A药物-药物相互作用（DDI）的潜力。然而,由于4β-HC的半衰期长，动态范围窄，它的使用仅限于CYP3A诱导剂的鉴定，但不是CYP3A抑制剂。从脱氧胆酸（DCA）形成1β-羟基脱氧胆酸（1β-OHDCA）是由CYP3A介导的，因此，1β-OHDCA可以作为4β-HC的替代品，用于评估CYP3ADDI潜力。为了研究这种可行性，我们开发了一种灵敏的LC-MS/MS方法，用于同时定量人血浆中1β-OHDCA及其甘氨酸和牛磺酸缀合物，LLOQ为50pg/mL，这使得基础水平的定量和进一步降低成为可能。将该方法应用于DDI研究以评估1β-OHDCA及其甘氨酸和牛磺酸缀合物如何响应CYP3A诱导或抑制。利福平诱导导致血浆中1β-OHDCA及其缀合物增加，与6.8-，7.8-，8.3-,AUCLST的10.3倍增加，AUC24h,总1β-OHDCA的Cmax和平均浓度（所有三种形式的总和），分别。重要的是,伊曲康唑抑制导致这些生物标志物的显著减少，84%,85%,82%,AUCLST减少81%，AUC24h,总1β-OHDCA的Cmax和平均浓度，分别。该初步数据首次表明，血浆中的总1β-OHDCA有可能在早期临床开发中用作CYP3ADDI评估的生物标志物，并且可能提供优于4β-HC的关键优势。显著性陈述我们已经报道了使用总1β-羟基脱氧胆酸(1β-OHDCA)(1β-OHDCA及其甘氨酸和牛磺酸缀合物的总和)血浆浓度作为CYP3A活性的生物标志物。伊曲康唑抑制导致1β-OHDCA血浆暴露总量减少81-85%，而利福平诱导导致1β-OHDCA血浆暴露总量增加6.8-10.3倍。使用血浆中的1β-OHDCA暴露还提供了允许使用相同基质进行PK和生物标志物评估的益处。从而简化收集程序。
