Centre for Molecular Oncology, Barts Cancer Institute, Queen Mary University of London, London, UK.
Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, CF14 4XN, UK.
Sci Rep. 2019 Sep 6;9(1):12840. doi: 10.1038/s41598-019-49150-9.
Early phase clinical trials have demonstrated good therapeutic index for oncolytic adenoviruses in patients with solid tumours when administered intratumorally, resulting in local tumour elimination. Entrapment and binding of adenovirus to erythrocytes, blood factors, and neutralising antibodies have prevented efficient systemic delivery and targeting of distant lesions in the clinic. We previously generated the novel replication-selective Ad-3∆-A20T to improve tumour targeting by increasing the viral dose at distant sites. Here, we developed a protocol to directly radiolabel the virus for rapid and sensitive detection by single-photon emitted computed tomography (SPECT/CT) providing a convenient method for determining biodistribution following intravenous administration in murine models. Longitudinal whole-body scans, demonstrated efficient viral uptake in pancreatic Suit-2 and Panc04.03 xenografts with trace amounts of I-Ad-3∆-A20T up to 48 h after tail vein delivery. Hepatic and splenic radioactivity decreased over time. Analysis of tissues harvested at the end of the study, confirmed potency and selectivity of mutant viruses. Ad-3∆-A20T-treated animals showed higher viral genome copy numbers and E1A gene expression in tumors than in liver and spleen compared to Ad5wt. Our direct radiolabeling approach, allows for immediate screening of novel oncolytic adenoviruses and selection of optimal viral genome alterations to generate improved mutants.
早期临床试验表明，在肿瘤内给药时，溶瘤腺病毒对实体瘤患者具有良好的治疗指数，可导致局部肿瘤消除。腺病毒与红细胞、血液因子和中和抗体的结合和捕获，阻止了有效的全身递送和对远处病变的靶向。我们之前生成了新型复制选择型 Ad-3∆-A20T，通过增加远处部位的病毒剂量来提高肿瘤靶向性。在这里，我们开发了一种直接放射性标记病毒的方案，用于单光子发射计算机断层扫描（SPECT/CT）的快速和灵敏检测，为静脉内给药后在小鼠模型中确定生物分布提供了一种方便的方法。纵向全身扫描显示，在胰腺 Suit-2 和 Panc04.03 异种移植中，I-Ad-3∆-A20T 的病毒摄取效率很高，在尾静脉给药后长达 48 小时仍可检测到微量的放射性。随着时间的推移，肝和脾中的放射性逐渐减少。研究结束时采集的组织分析证实了突变病毒的效力和选择性。与 Ad5wt 相比，Ad-3∆-A20T 处理的动物在肿瘤中的病毒基因组拷贝数和 E1A 基因表达均高于肝脏和脾脏。我们的直接放射性标记方法允许立即筛选新型溶瘤腺病毒，并选择最佳的病毒基因组改变以产生改良的突变体。
