Fluorine-18 radiolabeling of a nitrophenyl sulfoxide and its evaluation in an SK-RC-52 model of tumor hypoxia
作者:Evelyn Laurens、Shinn Dee Yeoh、Angela Rigopoulos、Graeme J. O'Keefe、Henri J. Tochon-Danguy、Lee Wenn Chong、Jonathan M. White、Andrew M. Scott、Uwe Ackermann
DOI:10.1002/jlcr.3426
日期:2016.8
The significance of imaging hypoxia with the positron emission tomography ligand [18F]FMISO has been demonstrated in a variety of cancers. However, the slow kinetics of [18F]FMISO require a 2-h delay between tracer administration and patient scanning. Labeled chloroethyl sulfoxides have shown faster kinetics and higher contrast than [18F]FMISO in a rat model of ischemic stroke. However, these nitrogen mustard analogues are unsuitable for routine production and use in humans. Here, we report on the synthesis and in vitro and in vivo evaluation of a novel sulfoxide, which contains an ester moiety for hydrolysis and subsequent trapping in hypoxic cells. Non-decay corrected yields of radioactivity were 1.18 ± 0.24% (n = 27, 2.5 ± 0.5% decay corrected radiochemical yield) based on K[18F]F. The radiotracer did not show any defluorination and did not undergo metabolism in an in vitro assay using S9 liver fractions. Imaging studies using an SK-RC-52 tumor model in BALB/c nude mice have revealed that [18F]1 is retained in hypoxic tumors and has similar hypoxia selectivity to [18F]FMISO. Because of a three times faster clearance rate than [18F]FMISO from normoxic tissue, [18F]1 has emerged as a promising new radiotracer for hypoxia imaging.
使用正电子发射断层扫描配体 [18F]FMISO 进行缺氧成像的重要性已在多种癌症中得到证实。然而,[18F]FMISO 的缓慢动力学需要示踪剂施用和患者扫描之间有 2 小时的延迟。在缺血性中风大鼠模型中,标记的氯乙基亚砜比 [18F]FMISO 显示出更快的动力学和更高的对比度。然而,这些氮芥类似物不适合常规生产和在人类中使用。在这里,我们报告了一种新型亚砜的合成以及体外和体内评估,该亚砜含有一个酯部分,用于水解并随后捕获缺氧细胞。基于K[18F]F,放射性的非衰变校正产率为1.18±0.24%(n=27,衰变校正放射化学产率为2.5±0.5%)。在使用 S9 肝脏组分的体外测定中,放射性示踪剂没有显示出任何脱氟现象,也没有发生代谢。在 BALB/c 裸鼠中使用 SK-RC-52 肿瘤模型进行的成像研究表明,[18F]1 保留在缺氧肿瘤中,并且具有与 [18F]FMISO 相似的缺氧选择性。由于在含氧量正常的组织中的清除率比 [18F]FMISO 快三倍,[18F]1 已成为一种有前途的用于缺氧成像的新型放射性示踪剂。