非定点方法构建的靶向CLDN18.2探针^(68)Ga-NOTA-376的体内外性质评价

In vitro and in vivo evaluation of targeted probe^(68)Ga-NOTA-376 constructed by non-site-specific labeling method for CLDN18.2

目的:以非定点标记的方法构建^(68)Ga标记的靶向CLDN18.2的正电子发射体层成像(positron emission tomography,PET)探针^(68)Ga-NOTA-376,并评价其体内外性质。方法:以p-SCN-Bn-NOTA为螯合剂,非定点偶联靶向CLDN18.2的纳米抗体376,得到前体NOTA-376,对偶联后的前体进行^(68)Ga放射性标记。通过放射性薄层色谱法(Radio thin layer chromatography,Raio-TLC)测定探针的标记率、放射化学纯度及体外稳定性,并进行探针在人胃腺癌小鼠模型的micro-PET/计算机体层成像(computed tomography,CT)显像实验。结果:^(68)Ga-NOTA-376显示出高标记率(89.98±0.07)%、高放射化学纯度(97.67±0.02)%以及较高的比活度(16.69±6.60)GBq/μmol,并且在5%人血清白蛋白(human serum albumin,HSA)和磷酸盐缓冲溶液(phosphate buffered saline,PBS)中保持稳定。Micro-PET/CT结果表明探针在CLDN18.2阳性肿瘤中的最大标准摄取值(maximum standard uptake value,SUVmax)显著高于CLDN18.2阴性肿瘤,4.0 h时CLDN18.2阳性肿瘤及CLDN18.2阴性肿瘤的SUVmax分别为9.08±0.33及1.92±0.32。结论:本研究以非定点标记的方法成功构建了靶向CLDN18.2探针^(68)Ga-NOTA-376,标记率高,具有良好的稳定性及靶向性,是一种有潜力的PET探针,可用于CLDN18.2蛋白表达水平的检测。

Objective:To construct a positron emission tomography(PET)probe,^(68)Ga-NOTA-376,targeting CLDN18.2 using a non-site-specific labeling method,and to evaluate its in vitro and in vivo properties.Methods:The chelating agent p-SCN-Bn-NOTA was used to non-site-specifically conjugate the nanobody 376 targeting CLDN18.2,resulting in the precursor NOTA-376,which was then radiolabeled with^(68)Ga.The labeling efficiency,radiochemical purity,and in vitro stability of the probe were determined by radiothin layer chromatography(Radio-TLC),and micro-PET/computed tomography(CT)imaging experiments were conducted in a nude mouse model of human gastric adenocarcinoma.Results:^(68)Ga-NOTA-376 demonstrated a high labeling yield(89.98±0.07)%,high radiochemical purity(97.67±0.02)%and high specific activity(16.69±6.60)GBq/μmol,and remained stable in 5%human serum albumin(HSA)and phosphate-buffered saline(PBS).Micro-PET/CT results indicated that the maximum standardized uptake value(SUVmax)of the probe in CLDN18.2-positive tumors was significantly higher than in CLDN18.2-negative tumors.At 4.0 h,the SUVmax of CLDN18.2-positive tumors and CLDN18.2-negative tumors were 9.08±0.33 and 1.92±0.32,respectively.Conclusion:This study successfully constructed a CLDN18.2-targeting probe^(68)Ga-NOTA-376 using a non-site-specific labeling method,which showed high labeling efficiency,good stability,and targeting capability,making it a potential PET probe for the detection of CLDN18.2 protein expression levels.