Bing Hao, Ma Yi, Xu Jiamin, Ling Qixian, Duan Yanlong, Zhao Libo
Clinical Research Center, Beijing Children's Hospital, Capital Medical University, Beijing, China.
Department of Pharmacy, Peking University Third Hospital, Beijing, China.
Cancer Med. 2025 Jan;14(2):e70516. doi: 10.1002/cam4.70516.
7-Hydroxymethotrexate (7-OHMTX) is the main metabolite in plasma following high-dose MTX (HD-MTX), which may result in activity and toxicity of the MTX. Moreover, 7-OHMTX could produce crystalline-like deposits within the renal tubules under acidic conditions or induce renal inflammation, oxidative stress, and cell apoptosis through various signaling pathways, ultimately leading to kidney damage. The objectives of this study were thus to explore the exposure-safety relationship of two compounds and search the most reliable marker for predicting HDMTX nephrotoxicity.
A total of 280 plasma concentration data (140 for MTX and 140 for 7-OHMTX) for 60 pediatric patients with non-Hodgkin lymphoma (NHL) were prospectively collected. Plasma MTX and 7-OHMTX concentrations were determined using a high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method. A nonlinear mixed effect model approach was used to build a joint population pharmacokinetic (PopPK) model. After validation, the model estimated the peak concentration (C) and area under the curve within the initial 48 h (AUC) of the patients after drug administration by Bayesian feedback. The receiver operating characteristic (ROC) curves were generated to identify an exposure threshold associated with nephrotoxicity.
A three-compartment chain model (central and peripheral compartments for MTX and central compartment 7-OHMTX) with the first-order elimination adequately characterized the in vivo process of MTX and 7-OHMTX. The covariate analysis identified that the aspartate aminotransferase (AST) was strongly associated with the peripheral volume of distribution of MTX. Moreover, the C of MTX and 7-OHMTX showed significant differences (p < 0.0001, p = 0.0472, respectively) among patients with or without nephrotoxicity. Similarly, individuals with nephrotoxicity also exhibited substantially higher ratio of 7-OHMTX to MTX peak concentration and the sum of MTX + 2.25 times the concentration of 7-OHMTX (p < 0.0001, p = 0.0426, respectively). By ROC analysis, the C of MTX and 7-OHMTX had the greatest area under the curve (AUC) values (0.769 and 0.771, respectively). A C threshold of 9.26 μmol/L for MTX or a C threshold of 0.66 μmol/L for 7-OHMTX was associated with the best sensitivity/specificity for toxicity events (MTX: sensitivity = 0.886; specificity = 0.70; 7-OHMTX: sensitivity = 0.886; specificity = 0.70).
We demonstrated that the C of MTX and 7-OHMTX were the most reliable markers associated with nephrotoxicity and proposed a C threshold of 9.26 μmol/L for MTX and 0.66 μmol/L for 7-OHMTX as the point with a high risk of nephrotoxicity. Altogether, this study may contribute to crucial insights for ensuring the safe administration of drugs in pediatric clinical practice.
7-羟基甲氨蝶呤（7-OHMTX）是高剂量甲氨蝶呤（HD-MTX）治疗后血浆中的主要代谢产物，这可能会导致甲氨蝶呤的活性和毒性。此外，7-OHMTX在酸性条件下可在肾小管内产生晶体样沉积物，或通过各种信号通路诱导肾脏炎症、氧化应激和细胞凋亡，最终导致肾损伤。因此，本研究的目的是探讨两种化合物的暴露-安全性关系，并寻找预测HD-MTX肾毒性最可靠的标志物。
前瞻性收集60例非霍奇金淋巴瘤（NHL）儿科患者的280份血浆浓度数据（甲氨蝶呤140份，7-OHMTX 140份）。采用高效液相色谱串联质谱（HPLC-MS/MS）法测定血浆中甲氨蝶呤和7-OHMTX的浓度。采用非线性混合效应模型方法建立联合群体药代动力学（PopPK）模型。验证后，该模型通过贝叶斯反馈估计患者给药后最初48小时内的峰浓度（C）和曲线下面积（AUC）。生成受试者工作特征（ROC）曲线以确定与肾毒性相关的暴露阈值。
具有一级消除的三室链模型（甲氨蝶呤的中央和外周室以及7-OHMTX的中央室）充分表征了甲氨蝶呤和7-OHMTX的体内过程。协变量分析确定，天冬氨酸转氨酶（AST）与甲氨蝶呤的外周分布容积密切相关。此外，有或无肾毒性的患者中甲氨蝶呤和7-OHMTX的C值存在显著差异（分别为p < 0.0001，p = 0.0472）。同样，有肾毒性的个体7-OHMTX与甲氨蝶呤峰浓度之比以及甲氨蝶呤 + 2.25倍7-OHMTX浓度之和也显著更高（分别为p < 0.0001，p = 0.0426）。通过ROC分析，甲氨蝶呤和7-OHMTX的C值具有最大的曲线下面积（AUC）值（分别为0.769和0.771）。甲氨蝶呤的C阈值为9.26 μmol/L或7-OHMTX的C阈值为0.66 μmol/L与毒性事件的最佳敏感性/特异性相关（甲氨蝶呤：敏感性 = 0.886；特异性 = 0.70；7-OHMTX：敏感性 = 0.886；特异性 = 0.70）。
我们证明甲氨蝶呤和7-OHMTX的C值是与肾毒性相关的最可靠标志物，并提出甲氨蝶呤的C阈值为9.26 μmol/L和7-OHMTX的C阈值为0.66 μmol/L作为肾毒性高风险点。总之，本研究可能有助于为确保儿科临床实践中的安全用药提供关键见解。
