Department of Medical Imaging, University of Saskatchewan, College of Medicine, Saskatoon, SK, Canada; Saskatchewan Centre for Cyclotron Sciences (SCCS), The Fedoruk Centre, Saskatoon, SK, Canada.
Department of Pathology and Laboratory Medicine, University of Saskatchewan, College of Medicine, Saskatoon, SK, Canada.
Eur J Med Chem. 2018 Sep 5;157:437-446. doi: 10.1016/j.ejmech.2018.08.014. Epub 2018 Aug 6.
Bifunctional chelators (BFCs) are covalently linked to biologically active targeting molecules and radiolabeled with radiometals. Technetium-99 m (Tc) is the most widely used isotope in nuclear medicine because of its excellent physical properties. The objective of this study was to synthesize and characterize a novel BFC that allows for the labeling of antibodies and antibody fragments using the Tc(CO) core which forms a very stable complex with Tc in the +1 oxidation sate. This study reports the synthesis of a BFC 1-pyrrolidinyl-2,5-dione-11-(bis((1-(carboxymethyl)-1H-imidazol-2-yl)methyl)amino)undecanoic acid (SAAC-CIM NHS ester), and the in vitro and in vivo evaluation of Tc(CO)-SAAC-CIM-DLO6-(scFv) (Tc(CO)-DLO6-(scFv)), a domain I/II-specific anti-epidermal growth factor receptor I (anti-EGFR) antibody fragment. The chelator allowed radiolabeling the (scFv) antibody fragment in very mild conditions with no significant decrease in binding to EGFR. Radiochemical yields of >50% (radiochemical purity > 95%) of the resulting anti-EGFR (scFv) immunoconjugate Tc(CO)-DLO6-(scFv) was obtained. The radioimmunoconjugate was stable in histidine challenge experiments with less than 20% transchelation at 24 h after challenge in the presence of a 1500-fold excess of histidine. In vivo biodistribution of Tc(CO)-DLO6-(scFv) indicates that the tracer was mainly cleared via renal excretion and to a lesser extent via the hepatobiliary pathway. The microSPECT imaging studies performed in mice confirmed the in vitro affinity results. The Tc(CO)-DLO6-(scFv) shows some promising properties and warrants further investigation for imaging EGFR.
双功能螯合剂(BFC)通过共价键与生物活性靶向分子连接,并通过放射性金属进行放射性标记。锝-99m(Tc)因其优异的物理性质而成为核医学中应用最广泛的同位素。本研究的目的是合成和表征一种新型 BFC,该 BFC 允许使用 Tc(CO)核标记抗体和抗体片段,其中 Tc(CO)在+1 氧化态下与 Tc 形成非常稳定的配合物。本研究报告了一种 BFC 1-吡咯烷二酮-11-(双((1-(羧甲基)-1H-咪唑-2-基)甲基)氨基)十一烷酸(SAAC-CIM NHS 酯)的合成,以及 Tc(CO)-SAAC-CIM-DLO6-(scFv)(Tc(CO)-DLO6-(scFv))的体外和体内评价,这是一种针对表皮生长因子受体 I(anti-EGFR)的 I/II 结构域特异性抗体片段。该螯合剂允许在非常温和的条件下对(scFv)抗体片段进行放射性标记,而对 EGFR 的结合没有明显降低。所得抗 EGFR(scFv)免疫偶联物 Tc(CO)-DLO6-(scFv)的放射化学产率>50%(放射化学纯度>95%)。在组氨酸挑战实验中,在存在 1500 倍过量组氨酸的情况下,24 小时后仅有不到 20%的转金属发生,该放射性免疫偶联物稳定。Tc(CO)-DLO6-(scFv)的体内生物分布表明,该示踪剂主要通过肾脏排泄清除,其次是通过肝胆途径清除。在小鼠中进行的 microSPECT 成像研究证实了体外亲和力结果。Tc(CO)-DLO6-(scFv)表现出一些有前景的特性,值得进一步研究用于成像 EGFR。