c-Gluc-Lys(Fe18FNOTA)-TOCA的制备及初步生物学评价

Preparation and Preliminary Biological Evaluation of c-Gluc-Lys(Fe18FNOTA)-TOCA

  • 摘要: 生长抑素类似物与肿瘤细胞上的生长抑素受体(SSTR)能够特异性地结合。因此,用18F标记的生长抑素类似物可作为肿瘤示踪剂对生长抑素受体阳性肿瘤进行诊断、分期和疗效评价。为开发一种可用于生长抑素受体阳性肿瘤诊断、能够高效快速合成的18F标记生长抑素类似物,本文用Fe18F复合物和偶联了双功能螯合剂1,4,7-三氮环壬烷-1,4,7-三乙酸(NOTA)的糖基化生长抑素类似物c-Gluc-Lys(NOTA)-TOCA通过螯合反应制备了c-Gluc-Lys(Fe18FNOTA)-TOCA,放化反应合成时间为25~30 min,标记率为40%,最终产品经HLB柱纯化后放化纯大于95%。标记物亲水性良好(lg P=-4.18±0.15),但体外稳定性差。正常鼠体内分布实验表明:标记物主要通过肾代谢,肝中摄取很低,在生长抑素受体高表达的胰腺中有高摄取,血液和肌肉本底低,骨中摄取高。本工作为进一步研究18F金属复合物标记的生长抑素类似物作为生长抑素受体阳性肿瘤显像剂提供了实验依据。

     

    Abstract: Somatostatin analogues can specificially bind with somatostatin receptor (SSTR) which is usually over-expressed on many tumor cells. So it may have important significance to use 18F labeled somatostatin analogues as the tumor probes for the diagnosis, the clinical staging and evaluation of therapeutic effect of SSTR positive tumor. In order to explore a novel PET probe for diagnosis of SSTR positive tumors, the c-Gluc-Lys(Fe18FNOTA)-TOCA was radio-synthesized fast and efficiently using the chelation reaction with Fe18F complex and c-Gluc-Lys(NOTA)-TOCA which was a glycosylated somatostatin analogues combined with 1,4,7-triazacyclononane-1,4,7 triacetic acid (NOTA). The labeling efficiency of c-Gluc-Lys(Fe18FNOTA)-TOCA is 40% and the total synthesis time is 25-30 min. The radiochemical purity is over 95% after HLB column purification. The hydrophily of the probe is high (lg P=-4.18±0.15), the stability in vitro is poor. Biodistribution studies in normal mice show that c-Gluc-Lys(Fe18FNOTA)-TOCA is excluded by kidneys, the uptake in liver is low, the uptake in SSTR expressed pancreas is high, the background of blood and muscle are low, the uptake in bone is high. These preliminary results provide some experimental basis for further study of 18F metal complex labeled somatostatin analogues as the tumor probes for the diagnosis of SSTR-positive tumor.

     

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