National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology (QST-NIRS), Chiba.
Center for Drug Design Research, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka.
Nucl Med Commun. 2020 Jul;41(7):688-695. doi: 10.1097/MNM.0000000000001203.
We previously reported In-labeled anti-cadherin17 (CDH17) IgG visualized CDH17-positive gastric cancer xenografts. Unfortunately, a long waiting time was required to obtain high-contrast images due to long blood retention (blood half-life: 26 h). To accelerate blood clearance, we have developed anti-CDH17 minibody (D2101 minibody) and evaluated the pharmacokinetics in gastric cancer mouse models.
Two different single chain Fvs (scFvs), D2101 mutant and D2111, were developed from each parental IgG. The binding ability to CDH17 and stability in plasma were evaluated. D2101 minibody, constructed based on D2101 mutant scFv, was labeled with Cu (Cu-D2101 minibody), and the in-vitro and in-vivo properties were evaluated by cell ELISA, biodistribution experiments, and PET imaging in mice bearing CDH17-positive AGS and CDH17-negative MKN74 tumors.
D2101 mutant and D2111 scFvs showed similar affinities to CDH17. D2101 mutant scFv was more stable than D2111 scFv in plasma. No loss of binding affinity of the D2101 minibody by chelate conjugation and radiolabeling procedures was observed. The biodistribution of Cu-D2101 minibody showed high uptake in AGS tumors and low uptake in MKN74. The blood half-life of Cu-D2101 minibody was 6.5 h. Improved blood clearance of Cu-D2101 minibody provided high tumor-to-blood ratios compared with the previous results of parental IgG in AGS xenograft mice. PET studies showed consistent results with biodistribution studies.
Cu-D2101 minibody exhibited higher tumor-to-blood ratios at earlier time points than those of the radiolabeled parental IgG. Cu-D2101 minibody has potential as an immunoimaging agent for CDH17-positive tumors.
我们之前报道了用抗钙粘蛋白 17（CDH17）抗体标记（In-labeled）的方法可视化 CDH17 阳性胃癌异种移植瘤。遗憾的是，由于血液半衰期长（26 小时），需要很长的等待时间才能获得高对比度的图像。为了加速血液清除，我们开发了抗 CDH17 迷你抗体（D2101 迷你抗体），并在胃癌小鼠模型中评估了其药代动力学。
从每个亲本 IgG 中开发了两种不同的单链 Fv（scFv），D2101 突变体和 D2111。评估了它们与 CDH17 的结合能力和在血浆中的稳定性。基于 D2101 突变体 scFv 构建了 D2101 迷你抗体，并用 Cu 标记（Cu-D2101 迷你抗体），并通过细胞 ELISA、生物分布实验和在携带 CDH17 阳性 AGS 和 CDH17 阴性 MKN74 肿瘤的小鼠中进行 PET 成像来评估其在体外和体内的特性。
D2101 突变体和 D2111 scFv 与 CDH17 具有相似的亲和力。D2101 突变体 scFv 在血浆中比 D2111 scFv 更稳定。螯合偶联和放射性标记过程没有观察到 D2101 迷你抗体结合亲和力的丧失。Cu-D2101 迷你抗体的生物分布显示在 AGS 肿瘤中有高摄取，在 MKN74 中有低摄取。Cu-D2101 迷你抗体的血液半衰期为 6.5 小时。与亲本 IgG 在 AGS 异种移植瘤小鼠中的先前结果相比，Cu-D2101 迷你抗体的血液清除率的提高提供了更高的肿瘤与血液比值。PET 研究结果与生物分布研究结果一致。
与放射性标记的亲本 IgG 相比，Cu-D2101 迷你抗体在更早的时间点显示出更高的肿瘤与血液比值。Cu-D2101 迷你抗体具有成为 CDH17 阳性肿瘤免疫成像剂的潜力。
