Interindividual Variation in CYP3A Activity Influences Lapatinib Bioactivation
Interindividual Variation in CYP3A Activity Influences Lapatinib Bioactivation
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DOI：
10.1124/dmd.119.088823
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发表时间：
2019-11-01
影响因子：
3.9
通讯作者：
Jackson, Klarissa D.
中科院分区：
文献类型：
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作者：
Bissada, Jennifer E.;Truong, Vivian;Jackson, Klarissa D.
拉帕替尼是一种双重酪氨酸激酶抑制剂，与罕见但可能严重的特异质肝毒性相关。我们之前已经证明，细胞色素P450 CYP 3A 4和CYP 3A 5定量有助于拉帕替尼生物活化，导致形成反应性的，潜在毒性的醌亚胺。CYP 3A 5具有高度多态性;然而，CYP 3A 5多态性对拉帕替尼代谢的影响尚未完全确定。本研究的目的是使用人体相关体外系统确定CYP 3A 5基因型和CYP 3A活性的个体差异对拉帕替尼代谢活化的影响。使用CYP 3A 5基因分型的人肝微粒体和冷冻保存的人肝细胞检查拉帕替尼代谢。分别使用探针底物咪达唑仑和T-5（T-1032）测定肝组织中的CYP 3A和CYP 3A 5选择性活性，以评价酶活性与拉帕替尼代谢产物形成之间的相关性。采用高效液相色谱-串联质谱法测定药物代谢产物。此外，使用CYP 3A的选择性化学抑制剂估计了CYP 3A 4和CYP 3A 5对拉帕替尼O-脱苄基的相对贡献。本研究的结果表明，拉帕替尼O-脱苄基和醌亚胺-GSH结合物形成与肝脏CYP 3A活性高度相关，通过咪达唑仑1 '-羟基化测定。在评价的所有肝组织中，CYP 3A 4在拉帕替尼生物活化中起主导作用。CYP 3A 5对拉帕替尼生物活化的贡献因个体供体而异，并取决于CYP 3A 5基因型和活性。CYP 3A 5对肝脏中来自CYP 3A 5表达者的拉帕替尼O-脱苄基作用贡献约20%-42%。这些发现表明，个体CYP 3A活性，而不是CYP 3A 5基因型单独，是拉帕替尼生物活化的关键决定因素，并可能影响暴露于活性代谢物。本研究结果表明，拉帕替尼通过氧化O-脱苄基作用的生物活化与总肝脏CYP 3A活性高度相关，而不仅仅是CYP 3A 5基因型。这些发现提供了对个体因素（即CYP 3A活性）的深入了解，这些因素可能影响个体暴露于拉帕替尼的反应性、潜在毒性代谢产物。
Lapatinib is a dual tyrosine kinase inhibitor associated with rare but potentially severe idiosyncratic hepatotoxicity. We have previously shown that cytochromes P450 CYP3A4 and CYP3A5 quantitatively contribute to lapatinib bioactivation, leading to formation of a reactive, potentially toxic quinone imine. CYP3A5 is highly polymorphic; however, the impact of CYP3A5 polymorphism on lapatinib metabolism has not been fully established. The goal of this study was to determine the effect of CYP3A5 genotype and individual variation in CYP3A activity on the metabolic activation of lapatinib using human-relevant in vitro systems. Lapatinib metabolism was examined using CYP3A5-genotyped human liver microsomes and cryo-preserved human hepatocytes. CYP3A and CYP3A5-selective activities were measured in liver tissues using probe substrates midazolam and T-5 (T-1032), respectively, to evaluate the correlation between enzymatic activity and lapatinib metabolite formation. Drug metabolites were measured by high-performance liquid chromatography-tandem mass spectrometry. Further, the relative contributions of CYP3A4 and CYP3A5 to lapatinib O-debenzylation were estimated using selective chemical inhibitors of CYP3A. The results from this study demonstrated that lapatinib O-debenzylation and quinone imine-GSH conjugate formation were highly correlated with hepatic CYP3A activity, as measured by midazolam 1'-hydroxylation. CYP3A4 played a dominant role in lapatinib bioactivation in all liver tissues evaluated. The CYP3A5 contribution to lapatinib bioactivation varied by individual donor and was dependent on CYP3A5 genotype and activity. CYP3A5 contributed approximately 20%-42% to lapatinib O-debenzylation in livers from CYP3A5 expressers. These findings indicate that individual CYP3A activity, not CYP3A5 genotype alone, is a key determinant of lapatinib bioactivation and likely influences exposure to reactive metabolites.SIGNIFICANCE STATEMENTThis study is the first to examine the effect of CYP3A5 genotype, total CYP3A activity, and CYP3A5-selective activity on lapatinib bioactivation in individual human liver tissues. The results of this investigation indicate that lapatinib bioactivation via oxidative O-debenzylation is highly correlated with total hepatic CYP3A activity, and not CYP3A5 genotype alone. These findings provide insight into the individual factors, namely, CYP3A activity, that may affect individual exposure to reactive, potentially toxic metabolites of lapatinib.