PET Imaging of Dll4 Expression in Glioblastoma and Colorectal Cancer Xenografts Using 64Cu-Labeled Monoclonal Antibody 61B

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• 作者：Bin Zhou ; Hui Wang ; Ren Liu ; Mengzhe Wang ; Huaifu Deng ; Benjamin C. Giglio ; Parkash S. Gill ; Hong Shan ; Zibo Li
• 刊名：Molecular Pharmaceutics
• 出版年：2015
• 出版时间：October 5, 2015
• 年：2015
• 卷：12
• 期：10
• 页码：3527-3534
• 全文大小：383K
• ISSN：1543-8392

文摘

Delta-like ligand 4 (Dll4) expressed in tumor cells plays a key role to promote tumor growth of numerous cancer types. Based on a novel antihuman Dll4 monoclonal antibody (61B), we developed a ⁶⁴Cu-labeled probe for positron emission tomography (PET) imaging of tumor Dll4 expression. In this study, 61B was conjugated with the ⁶⁴Cu-chelator DOTA through lysine on the antibody. Human IgG (hIgG)-DOTA, which did not bind to Dll4, was also prepared as a control. The Dll4 binding activity of the probes was evaluated through the bead-based binding assay with Dll4-alkaline phosphatase. The resulting PET probes were evaluated in U87MG glioblastoma and HT29 colorectal cancer xenografts in athymic nude mice. Our results demonstrated that the 61B-DOTA retained (77.2 卤 3.7) % Dll4 binding activity of the unmodified 61B, which is significantly higher than that of hIgG-DOTA (0.06 卤 0.03) %. Confocal microscopy analysis confirmed that 61B-Cy5.5, but not IgG-Cy5.5, predominantly located within the U87MG and HT29 cells cytoplasm. U87MG cells showed higher 61B-Cy5.5 binding as compared to HT29 cells. In U87MG xenografts, 61B-DOTA-⁶⁴Cu demonstrated remarkable tumor accumulation (10.5 卤 1.7 and 10.2 卤 1.2%ID/g at 24 and 48 h postinjection, respectively). In HT29 xenografts, tumor accumulation of 61B-DOTA-⁶⁴Cu was significantly lower than that of U87MG (7.3 卤 1.3 and 6.6 卤 1.3%ID/g at 24 and 48 h postinjection, respectively). The tumor accumulation of 61B-DOTA-⁶⁴Cu was significantly higher than that of hIgG-DOTA-⁶⁴Cu in both xenografts models. Immunofluorescence staining of the tumor tissues further confirmed that tumor accumulation of 61B-Cy5.5 was correlated well with in vivo PET imaging data using 61B-DOTA-⁶⁴Cu. In conclusion, 61B-DOTA-⁶⁴Cu PET probe was successfully synthesized and demonstrated prominent tumor uptake by targeting Dll4. 61B-DOTA-⁶⁴Cu has great potential to be used for noninvasive Dll4 imaging, which could be valuable for tumor detection, Dll4 expression level evaluation, and Dll4-based treatment monitoring.