Shen Yanfang, Zhou Renwei, Bi Lei, Huang Guolong, Yang Min, Li Zhijun, Yao Jijin, Xian Jianzhong, Qiu Yifan, Ye Peizhen, Liu Yongshan, Hou Yuyi, Jin Hongjun, Wang Ying
Department of Nuclear Medicine, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai 519000, China.
Guangdong Provincial Engineering Research Center of Molecular Imaging, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai 519000, China.
ACS Omega. 2024 Apr 5;9(15):17423-17431. doi: 10.1021/acsomega.4c00187. eCollection 2024 Apr 16.
As recurrent and metastatic nasopharyngeal carcinoma (NPC) is the most common cause of death among patients with NPC, there is an urgent clinical need for the development of precision diagnosis to guide personalized treatment. Recent emerging evidence substantiates the increased expression of transferrin receptor 1 (also known as cluster of differentiation 71, CD71) within tumor tissues and the inherent targeting capability of natural heavy-chain ferritin (HFn) toward CD71. This study aimed to synthesize and assess a radiotracer ([Cu]Cu-NOTA-HFn) designed to target CD71 for positron emission tomography (PET) imaging in an NPC tumor-bearing mouse model. The entire radiolabeling process of [Cu]Cu-NOTA-HFn was completed within 15 min with high yield (>98.5%) and high molar activity (72.96 ± 21.33 GBq/μmol). The in vitro solubility and stability experiments indicated that [Cu]Cu-NOTA-HFn had a high water solubility (log = -2.42 ± 0.52, = 6) and good stability in phosphate-buffered saline (PBS) for up to 48 h. The cell saturation binding assay indicated that [Cu]Cu-NOTA-HFn had a nanomolar affinity ( = 10.9 ± 6.1 nM) for CD71-overexpressing C666-1 cells. To test the target engagement in vivo, prolonged-time PET imaging was performed at 1, 6, 12, 24, and 36 h postinjection (p.i.) of [Cu]Cu-NOTA-HFn to C666-1 NPC tumor-bearing mice. The C666-1 tumors could be visualized by [Cu]Cu-NOTA-HFn and blocked by nonradiolabeled HFn. PET imaging quantitative analysis demonstrated that the uptake of [Cu]Cu-NOTA-HFn in C666-1 tumors peaked at 6 h p.i. and the best radioactive tumor-to-muscle ratio was 10.53 ± 3.11 ( = 3). Ex vivo biodistribution assay at 6 h p.i. showed that the tumor uptakes were 1.43 ± 0.23%ID/g in the nonblock group and 0.92 ± 0.2%ID/g in the block group ( = 3, < 0.05). Immunohistochemistry and immunofluorescence staining confirmed positive expression of CD71 and the uptake of HFn in C666-1 tumor tissues. In conclusion, our experiments demonstrated that [Cu]Cu-NOTA-HFn possesses a very high target engagement for CD71-positive NPC tumors and provided a fundamental basis for further clinical translation.
由于复发性和转移性鼻咽癌（NPC）是NPC患者最常见的死亡原因，临床上迫切需要开发精准诊断方法以指导个性化治疗。最近出现的证据证实了转铁蛋白受体1（也称为分化簇71，CD71）在肿瘤组织中的表达增加，以及天然重链铁蛋白（HFn）对CD71的内在靶向能力。本研究旨在合成并评估一种放射性示踪剂（[Cu]Cu-NOTA-HFn），该示踪剂设计用于在荷NPC肿瘤的小鼠模型中靶向CD71进行正电子发射断层扫描（PET）成像。[Cu]Cu-NOTA-HFn的整个放射性标记过程在15分钟内完成，产率高（>98.5%）且摩尔活性高（72.96±21.33 GBq/μmol）。体外溶解度和稳定性实验表明，[Cu]Cu-NOTA-HFn具有高水溶性（log = -2.42±0.52， = 6），并且在磷酸盐缓冲盐水（PBS）中长达48小时具有良好的稳定性。细胞饱和结合试验表明，[Cu]Cu-NOTA-HFn对过表达CD71的C666-1细胞具有纳摩尔亲和力（ = 10.9±6.1 nM）。为了测试体内的靶向结合情况，在向荷C666-1 NPC肿瘤的小鼠注射[Cu]Cu-NOTA-HFn后的1、6、12、24和36小时进行了长时间PET成像。[Cu]Cu-NOTA-HFn可以使C666-1肿瘤显影，并且可被未标记的HFn阻断。PET成像定量分析表明，[Cu]Cu-NOTA-HFn在C666-1肿瘤中的摄取在注射后6小时达到峰值，最佳放射性肿瘤与肌肉比值为10.53±3.11（ = 3）。注射后6小时的体外生物分布试验表明，非阻断组的肿瘤摄取为1.43±0.23%ID/g，阻断组为0.92±0.2%ID/g（ = 3， < 0.05）。免疫组织化学和免疫荧光染色证实了C666-1肿瘤组织中CD71的阳性表达和HFn的摄取。总之，我们的实验表明，[Cu]Cu-NOTA-HFn对CD71阳性的NPC肿瘤具有非常高的靶向结合能力，并为进一步的临床转化提供了基础依据。
