PDF(Pubmed)
Abstract：
BACKGROUND: Integrating radioactive and optical imaging techniques can facilitate the prognosis and surgical guidance for cancer patients. Using a single dual-labeled tracer ensures consistency in both imaging modalities. However, developing such molecule is challenging due to the need to preserve the biochemical properties of the tracer while introducing bulky labeling moieties. In our study, we designed a trifunctional chelate that facilitates the coupling of the targeting vector and fluorescent dye at opposite sites to avoid undesired steric hindrance effects. The synthesis of the trifunctional chelate N3-Py-DOTAGA-(tBu)3 (7) involved a five-step synthetic route, followed by conjugation to the linear peptidyl-resin 8 through solid-phase synthesis. After deprotection and cyclization, the near-infrared fluorescent dye sulfo-Cy.5 was introduced using copper free click chemistry, resulting in eTFC-01. Subsequently, eTFC-01 was labeled with [111In]InCl3. In vitro assessments of eTFC-01 binding, uptake, and internalization were conducted in SSTR2-transfected U2OS cells. Ex-vivo biodistribution and fluorescence imaging were performed in H69-tumor bearing mice.
RESULTS: eTFC-01 demonstrated a two-fold higher IC50 value for SSTR2 compared to the gold standard DOTA-TATE. Labeling of eTFC-01 with [111In]InCl3 gave a high radiochemical yield and purity. The uptake of [111In]In-eTFC-01 in U2OS.SSTR2 cells was two-fold lower than the uptake of [111In]In-DOTA-TATE, consistent with the binding affinity. Tumor uptake in H69-xenografted mice was lower for [111In]In-eTFC-01 at all-time points compared to [111In]In-DOTA-TATE. Prolonged blood circulation led to increased accumulation of [111In]In-eTFC-01 in highly vascularized tissues, such as lungs, skin, and heart. Fluorescence measurements in different organs correlated with the radioactive signal distribution.
CONCLUSIONS: The successful synthesis and coupling of the trifunctional chelate to the peptide and fluorescent dye support the potential of this synthetic approach to generate dual labeled tracers. While promising in vitro, the in vivo results obtained with [111In]In-eTFC-01 suggest the need for adjustments to enhance tracer distribution.
RESULTS: eTFC-01 demonstrated a two-fold higher IC50 value for SSTR2 compared to the gold standard DOTA-TATE. Labeling of eTFC-01 with [111In]InCl3 gave a high radiochemical yield and purity. The uptake of [111In]In-eTFC-01 in U2OS.SSTR2 cells was two-fold lower than the uptake of [111In]In-DOTA-TATE, consistent with the binding affinity. Tumor uptake in H69-xenografted mice was lower for [111In]In-eTFC-01 at all-time points compared to [111In]In-DOTA-TATE. Prolonged blood circulation led to increased accumulation of [111In]In-eTFC-01 in highly vascularized tissues, such as lungs, skin, and heart. Fluorescence measurements in different organs correlated with the radioactive signal distribution.
CONCLUSIONS: The successful synthesis and coupling of the trifunctional chelate to the peptide and fluorescent dye support the potential of this synthetic approach to generate dual labeled tracers. While promising in vitro, the in vivo results obtained with [111In]In-eTFC-01 suggest the need for adjustments to enhance tracer distribution.
摘要：
背景：整合放射性和光学成像技术可以促进癌症患者的预后和手术指导。使用单个双标记示踪剂可确保两种成像方式的一致性。然而,由于需要在引入庞大的标记部分的同时保持示踪剂的生化特性,开发这样的分子是具有挑战性的。在我们的研究中,我们设计了一种三官能螯合物，促进靶向载体和荧光染料在相对位点的偶联，以避免不希望的空间位阻效应。三官能螯合物N3-Py-DOTAGA-（tBu）3（7）的合成涉及五步合成路线，然后通过固相合成与线性肽基树脂8缀合。脱保护和环化后，近红外荧光染料sulfo-Cy.5是使用无铜点击化学引入的，导致eTFC-01。随后，eTFC-01用[111In]InCl3标记。eTFC-01结合的体外评估，摄取，和内化在SSTR2转染的U2OS细胞中进行。在H69荷瘤小鼠中进行离体生物分布和荧光成像。
结果：eTFC-01显示与黄金标准DOTA-TATE相比，SSTR2的IC50值高出两倍。用[111In]InCl3标记eTFC-01得到高放射化学产率和纯度。[111In]In-eTFC-01在U2OS中的摄取。SSTR2细胞比[111In]In-DOTA-TATE的摄取低两倍，与结合亲和力一致。与[111In]In-DOTA-TATE相比,[111In]In-eTFC-01在所有时间点H69异种移植小鼠中的肿瘤摄取较低。延长血液循环导致[111In]In-eTFC-01在高度血管化组织中的积累增加，比如肺，皮肤,和心脏。不同器官的荧光测量与放射性信号分布相关。
结论：三官能螯合物与肽和荧光染料的成功合成和偶联支持了这种合成方法产生双重标记示踪剂的潜力。虽然在体外有希望，使用[111In]In-eTFC-01获得的体内结果表明，需要进行调整以增强示踪剂分布。
结果：eTFC-01显示与黄金标准DOTA-TATE相比，SSTR2的IC50值高出两倍。用[111In]InCl3标记eTFC-01得到高放射化学产率和纯度。[111In]In-eTFC-01在U2OS中的摄取。SSTR2细胞比[111In]In-DOTA-TATE的摄取低两倍，与结合亲和力一致。与[111In]In-DOTA-TATE相比,[111In]In-eTFC-01在所有时间点H69异种移植小鼠中的肿瘤摄取较低。延长血液循环导致[111In]In-eTFC-01在高度血管化组织中的积累增加，比如肺，皮肤,和心脏。不同器官的荧光测量与放射性信号分布相关。
结论：三官能螯合物与肽和荧光染料的成功合成和偶联支持了这种合成方法产生双重标记示踪剂的潜力。虽然在体外有希望，使用[111In]In-eTFC-01获得的体内结果表明，需要进行调整以增强示踪剂分布。
