Zirconium- 89 Labeled Antibody K1-70 for PET Imaging of Thyroid-stimulating Hormone Receptor Expression in Thyroid Cancer.

IF 3 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Molecular Imaging and Biology Pub Date : 2024-10-01 Epub Date: 2024-08-22 DOI:10.1007/s11307-024-01945-7

Ephraim E Parent, Justyna J Gleba, Joshua A Knight, Saad J Kenderian, John A Copland, Hancheng Cai

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引用次数: 0

Abstract

Purpose: Thyroid-stimulating hormone receptor (TSHR) is a G-protein coupled receptor that is highly expressed on benign and malignant thyroid tissues. TSHR binding and activation has long been a component of thyroid cancer molecular imaging and radiotherapy, by promoting expression of the sodium-iodide symporter (NIS) and incorporation of I-131 into thyroid hormones. Here, we report the radiosynthesis and preclinical evaluation of a Zirconium-89 (⁸⁹Zr) labeled TSHR antibody to serve as a positron emission tomography (PET) diagnostic correlate for therapeutic agents targeting TSHR without reliance on NIS.

Procedures: TSHR human monoclonal antibody K1-70 was conjugated to chelator desferrioxamine-p-benzyl-isothiocyanate, followed by labeling with Zr-89, yielding the radiotracer ⁸⁹Zr-DFO-TSHR-Ab. The in vitro cellar uptake and binding affinity of ⁸⁹Zr-DFO-TSHR-Ab were analyzed in three new TSHR stable overexpressing tumor cell lines and their corresponding wild types (WT) with low or no TSHR expression. ⁸⁹Zr-DFO-TSHR-Ab PET/CT imaging of TSHR expression was evaluated in tumor mouse models bearing one TSHR-positive tumor and other negative control with or without the coinjection of antibody K1-70, and then verified by radiotracer biodistribution study and tumor immunohistochemistry (IHC).

Results: The conjugate DFO-TSHR-Ab was labeled with Zr-89 at 37 °C for 60 min and purified by PD-10 column in radiochemical yields of 68.8 ± 9.9%, radiochemical purities of 98.7 ± 0.8%, and specific activities of 19.1 ± 2.7 mCi/mg (n = 5). In vitro cell studies showed ⁸⁹Zr-DFO-TSHR-Ab had significantly high uptake on TSHR expressing tumor cells with nanomolar affinity and high potency. Preclinical PET/CT imaging revealed that ⁸⁹Zr-DFO-TSHR-Ab selectively detected TSHR expressing thyroid tumors and displayed improved in vivo performance with the coinjection of unlabeled TSHR antibody K1-70 leading to higher uptake in TSHR expressing tumors than parental WT tumors and physiologic tissues; this observation was confirmed by the biodistribution and immunostaining analyses.

Conclusions: We synthesized ⁸⁹Zr-labeled antibody K1-70 as a new radiopharmaceutical for PET imaging of TSHR. ⁸⁹Zr-DFO-TSHR-Ab has high radioactive uptake and retention in TSHR expressing tumors and cleared quickly from most background tissues in mouse models. Our study demonstrated that ⁸⁹Zr-DFO-TSHR-Ab has the potential for PET imaging of TSHR-positive thyroid cancer and monitoring TSHR-targeted therapy.

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用于甲状腺癌促甲状腺激素受体表达 PET 成像的锆 89 标记抗体 K1-70。

目的：促甲状腺激素受体（TSHR）是一种G蛋白偶联受体，在良性和恶性甲状腺组织中均高度表达。通过促进钠碘合酶（NIS）的表达和 I-131 与甲状腺激素的结合，TSHR 的结合和激活长期以来一直是甲状腺癌分子成像和放射治疗的一个组成部分。在此，我们报告了一种锆-89（89Zr）标记的 TSHR 抗体的放射合成和临床前评估，该抗体可作为正电子发射断层扫描（PET）诊断的相关物，用于靶向 TSHR 的治疗药物，而无需依赖 NIS：TSHR人类单克隆抗体K1-70与螯合剂去铁胺-对苄基异硫氰酸酯结合，然后用Zr-89标记，得到放射性示踪剂89Zr-DFO-TSHR-Ab。研究人员在三种新的TSHR稳定过表达肿瘤细胞系和相应的TSHR低表达或无表达的野生型（WT）细胞系中分析了89Zr-DFO-TSHR-Ab的体外细胞摄取和结合亲和力。在同时注射或不注射 K1-70 抗体的 TSHR 阳性肿瘤和阴性对照的肿瘤小鼠模型中，评估了 89Zr-DFO-TSHR-Ab PET/CT 成像对 TSHR 表达的影响，然后通过放射性示踪剂生物分布研究和肿瘤免疫组化（IHC）进行了验证：共轭物DFO-TSHR-Ab在37 ℃下用Zr-89标记60分钟，经PD-10柱纯化，放射化学收率为68.8 ± 9.9%，放射化学纯度为98.7 ± 0.8%，比活度为19.1 ± 2.7 mCi/mg（n = 5）。体外细胞研究表明，89Zr-DFO-TSHR-Ab 在表达 TSHR 的肿瘤细胞上具有明显的高摄取率、纳摩尔亲和力和高效力。临床前PET/CT成像显示，89Zr-DFO-TSHR-Ab可选择性地检测到表达TSHR的甲状腺肿瘤，并在体内与未标记的TSHR抗体K1-70同时注射时显示出更好的性能，导致TSHR表达肿瘤的摄取量高于亲代WT肿瘤和生理组织；生物分布和免疫染色分析证实了这一观察结果：我们合成了89Zr标记的抗体K1-70，作为一种新的放射性药物用于TSHR的PET成像。在小鼠模型中，89Zr-DFO-TSHR-Ab 在表达 TSHR 的肿瘤中具有较高的放射性摄取和保留率，并能迅速从大多数本底组织中清除。我们的研究表明，89Zr-DFO-TSHR-Ab 有潜力用于 TSHR 阳性甲状腺癌的 PET 成像和 TSHR 靶向治疗的监测。

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来源期刊

Molecular Imaging and Biology 医学-核医学

CiteScore

6.90

自引率

3.20%

发文量

审稿时长

3 months

期刊介绍： Molecular Imaging and Biology (MIB) invites original contributions (research articles, review articles, commentaries, etc.) on the utilization of molecular imaging (i.e., nuclear imaging, optical imaging, autoradiography and pathology, MRI, MPI, ultrasound imaging, radiomics/genomics etc.) to investigate questions related to biology and health. The objective of MIB is to provide a forum to the discovery of molecular mechanisms of disease through the use of imaging techniques. We aim to investigate the biological nature of disease in patients and establish new molecular imaging diagnostic and therapy procedures. Some areas that are covered are: Preclinical and clinical imaging of macromolecular targets (e.g., genes, receptors, enzymes) involved in significant biological processes. The design, characterization, and study of new molecular imaging probes and contrast agents for the functional interrogation of macromolecular targets. Development and evaluation of imaging systems including instrumentation, image reconstruction algorithms, image analysis, and display. Development of molecular assay approaches leading to quantification of the biological information obtained in molecular imaging. Study of in vivo animal models of disease for the development of new molecular diagnostics and therapeutics. Extension of in vitro and in vivo discoveries using disease models, into well designed clinical research investigations. Clinical molecular imaging involving clinical investigations, clinical trials and medical management or cost-effectiveness studies.