Department of Bioanalysis and Pharmacokinetics, Zealand Pharma A/S, Sydmarken 11, 2860, Søborg, Denmark.
Department of Pharmacy, Copenhagen University, Universitetsparken 2, 2100, Copenhagen Ø, Denmark.
Anal Bioanal Chem. 2022 Oct;414(24):7167-7177. doi: 10.1007/s00216-022-04269-z. Epub 2022 Aug 11.
Therapeutic peptides are a fast-growing class of pharmaceuticals. Like small molecules, the costs associated with their discovery and development are significant. In addition, since the preclinical data guides first-in-human studies, there is a need for analytical techniques that accelerate and improve our understanding of the absorption, distribution, metabolism, and excretion (ADME) characteristics of early drug candidates. Mass spectrometry imaging (MSI), which can be used to visualize drug distribution in intact tissue, has been extensively used to study small molecule drugs, but only applied to a limited extent to larger molecules, such as peptides, after dosing. Herein, we use MSI to obtain spatial information on the distribution and metabolism of a peptide drug. The immunosuppressant cyclosporine (CsA), a cyclic undecapeptide, was used as a-proof-of-concept peptide and investigated by desorption electrospray ionization (DESI) MSI. Calibration curves were made based on a spiked tissue homogenate model. Different washing protocols were tested to improve sensitivity, but CsA, being a quite lipophilic peptide, was found not to benefit from tissue washing. The distribution of CsA and its metabolites were mapped in whole-body mouse sections and within rat organs. Whole-body DESI-MSI studies in mice showed widespread distribution of CsA with highest abundance in organs like the pancreas and liver. After 24 h, hydroxy and dihydroxy metabolites of CsA were detected predominantly in the intestines, which were largely devoid of CsA. In addition to the DESI-MSI experiments, MALDI-MSI was also conducted on rat jejunum at higher spatial resolution, revealing the morphology of the jejenum at greater detail; however, DESI provided similar results for drug and metabolite distribution in rat jejunum at apparent slightly better sensitivity. Given its label-free nature, MSI could provide valuable ADME insight, especially for candidates in the early-stage pipeline before radiolabeling.
治疗性肽是一类快速发展的药物。与小分子药物一样，其发现和开发的成本也很高。此外，由于临床前数据指导首次人体研究，因此需要分析技术来加速和提高我们对早期候选药物的吸收、分布、代谢和排泄（ADME）特征的理解。可用于可视化完整组织中药物分布的质谱成像（MSI）已广泛用于研究小分子药物，但在给药后仅在有限程度上应用于较大分子，如肽。在此，我们使用 MSI 获得肽类药物分布和代谢的空间信息。免疫抑制剂环孢素（CsA），一种环状十一肽，被用作概念验证肽，并通过解吸电喷雾电离（DESI）MSI 进行了研究。根据加标组织匀浆模型制作了校准曲线。测试了不同的洗涤方案以提高灵敏度，但由于 CsA 是一种相当亲脂性的肽，因此发现它不能从组织洗涤中受益。在全身体小鼠切片和大鼠器官内绘制了 CsA 及其代谢物的分布。在小鼠的全身 DESI-MSI 研究中，CsA 广泛分布，在胰腺和肝脏等器官中含量最高。24 小时后，主要在肠道中检测到 CsA 的羟基和二羟基代谢物，肠道中 CsA 大量缺乏。除了 DESI-MSI 实验外，还在更高空间分辨率下对大鼠空肠进行了 MALDI-MSI，更详细地揭示了空肠的形态；然而，DESI 对大鼠空肠中药物和代谢物分布的结果与 MALDI 相似，灵敏度略有提高。鉴于其无标记的性质，MSI 可以提供有价值的 ADME 见解，尤其是对于早期候选药物在放射性标记之前。
