Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland.
Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland.
Theranostics. 2020 Jan 1;10(4):1678-1693. doi: 10.7150/thno.40482. eCollection 2020.
Prostate-specific membrane antigen (PSMA)-targeted radioligands have been used for the treatment of metastatic castration-resistant prostate cancer (mCRPC). Recently, albumin-binding PSMA radioligands with enhanced blood circulation were developed to increase the tumor accumulation of activity. The present study aimed at the design, synthesis and preclinical evaluation of a novel class of PSMA-targeting radioligands equipped with ibuprofen as a weak albumin-binding entity in order to improve the pharmacokinetic properties. : Four novel glutamate-urea-based PSMA ligands were synthesized with ibuprofen, conjugated via variable amino acid-based linker entities. The albumin-binding properties of the Lu-labeled PSMA ligands were tested using mouse and human plasma. Affinity of the radioligands to PSMA and cellular uptake and internalization was investigated using PSMA-positive PC-3 PIP and PSMA-negative PC-3 flu tumor cells. The tissue distribution profile of the radioligands was assessed in biodistribution and imaging studies using PC-3 PIP/flu tumor-bearing nude mice. : The PSMA ligands were obtained in moderate yields at high purity (>99%). Lu-labeling of the ligands was achieved at up to 100 MBq/nmol with >96% radiochemical purity. assays confirmed high binding of all radioligands to mouse and human plasma proteins and specific uptake and internalization into PSMA-positive PC-3 PIP tumor cells. Biodistribution studies and SPECT/CT scans revealed high accumulation in PC-3 PIP tumors but negligible uptake in PC-3 flu tumor xenografts as well as rapid clearance of activity from background organs and tissues. Lu-Ibu-DAB-PSMA, in which ibuprofen was conjugated via a positively-charged diaminobutyric acid (DAB) entity, showed distinguished tumor uptake and the most favorable tumor-to-blood and tumor-to-kidney ratios. : The high accumulation of activity in the tumor and fast clearance from background organs was a common favorable characteristic of PSMA radioligands modified with ibuprofen as albumin-binding entity. Lu-Ibu-DAB-PSMA emerged as the most promising candidate; hence, more detailed preclinical investigations with this radioligand are warranted in view of a clinical translation.
前列腺特异性膜抗原 (PSMA)-靶向放射性配体已被用于治疗转移性去势抵抗性前列腺癌 (mCRPC)。最近,开发了具有增强血液循环的结合白蛋白的 PSMA 放射性配体,以增加活性在肿瘤中的积累。本研究旨在设计、合成和临床前评估一类新型 PSMA 靶向放射性配体,该配体带有布洛芬作为弱白蛋白结合实体,以改善其药代动力学特性。
合成了四种新型谷氨酸-尿素基 PSMA 配体,通过可变氨基酸基连接体与布洛芬连接。使用小鼠和人血浆测试了 Lu 标记的 PSMA 配体的白蛋白结合特性。使用 PSMA 阳性 PC-3 PIP 和 PSMA 阴性 PC-3 氟尿嘧啶肿瘤细胞研究了放射性配体对 PSMA 的亲和力以及细胞摄取和内化。使用 PC-3 PIP/氟尿嘧啶荷瘤裸鼠进行生物分布和成像研究评估了放射性配体的组织分布特征。
PSMA 配体以中等产率和高纯度 (>99%)获得。配体的 Lu 标记最高可达 100 MBq/nmol,放射化学纯度>96%。结合测定证实所有放射性配体与小鼠和人血浆蛋白均具有高结合能力,并且特异性摄取和内化到 PSMA 阳性 PC-3 PIP 肿瘤细胞中。生物分布研究和 SPECT/CT 扫描显示,放射性配体在 PC-3 PIP 肿瘤中高度积聚,但在 PSMA 阴性 PC-3 氟尿嘧啶肿瘤异种移植中摄取可忽略不计,并且活性从背景器官和组织中快速清除。其中,布洛芬通过带正电荷的二氨基丁酸 (DAB) 基团连接的 Lu-Ibu-DAB-PSMA 显示出突出的肿瘤摄取和最有利的肿瘤与血液和肿瘤与肾脏的比值。
活性在肿瘤中的高度积聚和从背景器官中的快速清除是用布洛芬作为白蛋白结合实体修饰的 PSMA 放射性配体的共同有利特征。Lu-Ibu-DAB-PSMA 是最有前途的候选药物;因此,鉴于其向临床转化,需要对这种放射性配体进行更详细的临床前研究。