Hormone Laboratory, Department of Medical Biochemistry and Pharmacology, Haukeland University Hospital, Bergen, Vestland, 5009, Norway.
Department of Clinical Science, University of Bergen, Bergen, 5021, Norway.
J Clin Endocrinol Metab. 2022 Apr 19;107(5):1368-1374. doi: 10.1210/clinem/dgab923.
Currently there are no assays that can simultaneously quantify serum levels of the third-generation aromatase inhibitors (AIs): letrozole, anastrozole, and exemestane, and the ultra-low levels of estrogens in postmenopausal breast cancer patients on AI treatment. Such measurements may be pivotal for the determination of optimal and individualized treatment regimens. We aimed at developing a liquid chromatography-tandem mass spectrometry (MS/MS) method for simultaneous assessment of letrozole, anastrozole, exemestane, and 17-hydroxyexemestane as well as subpicomolar levels of estradiol and estrone.
Internal standards, calibrators, serum samples, and quality controls were in fully automated steps transferred to a deep-well plate for a 2-step liquid-liquid extraction. The extracts were reconstituted and analytes were separated chromatographically using 2 serially coupled columns, then subject to MS/MS in electrospray ionization mode. The method was thoroughly validated and is traceable to 2 accredited estrogen methods.
The measurement range for estrone and estradiol was 0.2 to 12 000 pmol/L and 0.8 to 13 000 pmol/L, and covered the expected therapeutic range for the AIs. All analytes had a precision of less than or equal to 13%, and accuracies within 100 ± 8%. As proof of concept, AI and estrogen levels were determined in serum samples from postmenopausal breast cancer patients under treatment.
We present here an assay suitable for the simultaneous measurement of serum levels of all third-generation AIs and ultra-low levels of estrogens, providing a powerful new tool to study drug efficacy and compliance. The method is highly valuable for postmenopausal patients whose pretreatment estradiol levels are below the threshold of detection for most routine assays, but still require suppression.
目前尚无能够同时定量检测第三代芳香酶抑制剂（AIs）：来曲唑、阿那曲唑和依西美坦，以及接受 AI 治疗的绝经后乳腺癌患者极低水平雌激素的检测方法。这些测量可能对确定最佳和个体化治疗方案至关重要。我们旨在开发一种液相色谱-串联质谱（MS/MS）方法，用于同时评估来曲唑、阿那曲唑、依西美坦和 17-羟基依西美坦以及亚皮摩尔水平的雌二醇和雌酮。
内标物、校准品、血清样本和质控品在全自动步骤中转移到深孔板中进行 2 步液-液萃取。提取物复溶后，用 2 根串联的色谱柱进行分离，然后采用电喷雾电离模式进行 MS/MS。该方法经过全面验证，可溯源至 2 种经认可的雌激素方法。
雌酮和雌二醇的测量范围分别为 0.2 至 12000 pmol/L 和 0.8 至 13000 pmol/L，涵盖了 AI 的预期治疗范围。所有分析物的精密度均小于或等于 13%，准确度在 100 ± 8%范围内。作为概念验证，我们测定了接受治疗的绝经后乳腺癌患者血清样本中的 AI 和雌激素水平。
我们在此介绍了一种适合同时测量所有第三代 AIs 和极低水平雌激素的检测方法，为研究药物疗效和依从性提供了一种强大的新工具。对于大多数常规检测方法检测不到的绝经前患者，但仍需要抑制的患者，该方法具有很高的价值。
