A practical synthesis of [<sup>18</sup>F]FtRGD: an angiogenesis biomarker for PET
作者:Romain Bejot、Julian Goggi、Shebbrin S. Moonshi、Edward G. Robins
DOI:10.1002/jlcr.3019
日期:2013.2
Integrins have become increasingly attractive targets for molecular imaging of angiogenesis with positron emission tomography or single-photon emission computed tomography, but the reliable production of radiopharmaceuticals remains challenging. A strategy for chemoselective labeling of the integrin ligand—c(RGDyK) peptide—has been developed on the basis of the Cu(I)-catalyzed conjugation reaction. Recently, we reported a nucleophilic detagging and fluorous solid-phase extraction method providing an easy way to implement an approach for obtaining 2-[18F]fluoroethyl azide. In this work, we report the practical use of this method for the preparation of the 2-[18F]fluoroethyl-triazolyl conjugated c(RGDyK) peptide: [18F]FtRGD. The two-step, two-pot synthesis, HPLC purification, and reformulation could be readily performed with a standard nucleophilic radiofluorination synthesizer (GE TRACERlab FXFN), with minimal modifications. [18F]FtRGD was obtained in a solution for injection (>500 MBq/mL) in 10–30% nondecay-corrected radiochemical yield, excellent radiochemical purity (>98%), and 28 ± 13 GBq/µmol specific activity. [18F]FtRGD (Ki = 54 ± 14 nM for αVβ3 and 1.7 ± 0.2 nM for αVβ5) was evaluated in mice and showed good stability in vivo, good tumor-to-background ratio (1.6 ± 0.3 %ID/g at 1.5 h post-injection in U87-MG tumors), and rapid urinary excretion. Therefore, [18F]FtRGD proved valuable for preclinical positron emission tomography imaging of integrin expression.
整合素已成为正电子发射断层扫描或单光子发射计算机断层扫描血管生成分子成像越来越有吸引力的目标,但放射性药物的可靠生产仍然具有挑战性。基于 Cu(I) 催化的缀合反应,开发了一种化学选择性标记整合素配体 c(RGDyK) 肽的策略。最近,我们报道了一种亲核脱标签和含氟固相萃取方法,为实现获得 2-[18F]氟乙基叠氮化物的方法提供了一种简单的方法。在这项工作中,我们报告了该方法在制备 2-[18F]氟乙基-三唑基缀合的 c(RGDyK) 肽:[18F]FtRGD 中的实际应用。两步、两锅合成、HPLC 纯化和重新配制可以使用标准亲核放射性氟化合成仪 (GE TRACERlab FXFN) 轻松进行,只需进行最少的修改。 [18F]FtRGD 在注射溶液中获得 (>500 MBq/mL),具有 10–30% 非衰变校正放射化学产率、优异的放射化学纯度 (>98%) 和 28 ± 13 GBq/μmol 比活度。 [18F]FtRGD(对于αVβ3,Ki = 54 ±14 nM;对于αVβ5,Ki = 54 ±14 nM;对于αVβ5,Ki = 54 ±0.2 nM)在小鼠中进行了评估,并显示出良好的体内稳定性和良好的肿瘤背景比(1.5小时时为1.6 ± 0.3 %ID/g) U87-MG 肿瘤注射后),并快速经尿排泄。因此,[18F]FtRGD 被证明对于整合素表达的临床前正电子发射断层扫描成像有价值。