Site-specifically labeled 89Zr-DFO-trastuzumab improves immuno-reactivity and tumor uptake for immuno-PET in a subcutaneous HER2-positive xenograft mouse model
Site-specifically labeled 89Zr-DFO-trastuzumab improves immuno-reactivity and tumor uptake for immuno-PET in a subcutaneous HER2-positive xenograft mouse model
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DOI：
10.7150/thno.32883
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发表时间：
2019-01-01
期刊：
影响因子：
12.4
通讯作者：
Nielsen, Carsten H.
中科院分区：
文献类型：
--
作者：
Kristensen, Lotte K.;Christensen, Camilla;Nielsen, Carsten H.
基于抗体的PET示踪剂特别适合于测定治疗性抗体的体内生物分布和定量。基于抗体的治疗剂的持续扩展相应地驱动了向更稳健的缀合策略的发展，以便可靠地预测此类药剂的性能。因此，我们的目的是评估酶重塑位点特异性标记对单克隆抗体（mAb）曲妥珠单抗的稳定性、免疫反应性和肿瘤靶向特性的影响，并将其与HER 2阳性异种移植小鼠模型中的常规随机标记进行比较。曲妥珠单抗与p-SCN-Bn-去铁胺缀合在Zr-89放射性标记之前，使用β-半乳糖苷酶或内切糖苷酶S2，在赖氨酸残基上随机地或在酶促修饰的聚糖上位点特异性地使用（SCN-Bn-DFO）螯合剂。将Zr-89-DFO-曲妥珠单抗注射到携带SK-0 V-3肿瘤的NMRI裸鼠中。用100 μ g或500 μ g未标记的曲妥珠单抗滴定抗体剂量。小鼠在注射后24、70和120小时进行小动物PET/CT成像以进行纵向评估。用同种型对照匹配抗体进行平行实验。体内成像得到常规离体生物分布和HER 2免疫组织化学的支持。此外，在一组皮下患者来源的异种移植物（PDX）模型中评价了位点特异性标记的Zr-89-DFO-曲妥珠单抗。结果：位点特异性标记显著增加PET肿瘤摄取（单因素方差分析，p
Antibody-based PET tracers are exceptionally well-suited for determination of the in vivo biodistribution and quantification of therapeutic antibodies. The continued expansion in antibody-based therapeutics has accordingly driven the development towards more robust conjugation strategies in order to reliably predict the performance of such agents. We therefore aimed to evaluate the effect of site-specific labeling by enzymatic remodeling on the stability, immuno-reactivity and tumor-targeting properties of the monoclonal antibody (mAb) trastuzumab and compare it to conventional, random labeling in a HER2-positive xenograft mouse model.Methods: Trastuzumab was conjugated with the p-SCN-Bn-Desferrioxamine (SCN-Bn-DFO) chelator randomly on lysine residues or site-specifically on enzymatically modified glycans using either beta-galactosidase or endoglycosidase S2 prior to Zr-89 radiolabeling. Zr-89-DFO-trastuzumab was injected into SK-OV-3 tumor-bearing NMRI nude mice. The antibody dose was titrated with either 100 mu g or 500 mu g of unlabeled trastuzumab. Mice underwent small animal PET/CT imaging 24, 70 and 120 hours post-injection for longitudinal assessment. Parallel experiments were conducted with an isotype control matched antibody. In vivo imaging was supported by conventional ex vivo biodistribution and HER2 immuno-histochemistry. Furthermore, site-specifically labeled Zr-89-DFO-trastuzumab was evaluated in a panel of subcutaneous patient-derived xenograft (PDX) models. Additionally, the affinity, in vitro stability and immuno-reactivity were assessed for all tracers.Results: Site-specific labeling significantly increased PET tumor uptake (One-way ANOVA, p