Shi Sixiang, Hong Hao, Orbay Hakan, Graves Stephen A, Yang Yunan, Ohman Jakob D, Liu Bai, Nickles Robert J, Wong Hing C, Cai Weibo
Materials Science Program, University of Wisconsin, Madison, WI, USA.
Eur J Nucl Med Mol Imaging. 2015 Jul;42(8):1295-303. doi: 10.1007/s00259-015-3038-1. Epub 2015 Mar 24.
To date, there is no effective therapy for triple-negative breast cancer (TNBC), which has a dismal clinical outcome. Upregulation of tissue factor (TF) expression leads to increased patient morbidity and mortality in many solid tumor types, including TNBC. Our goal was to employ the Fab fragment of ALT-836, a chimeric anti-human TF mAb, for PET imaging of TNBC, which can be used to guide future TNBC therapy.
ALT-836-Fab was generated by enzymatic papain digestion. SDS-PAGE and FACS studies were performed to evaluate the integrity and TF binding affinity of ALT-836-Fab before NOTA conjugation and (64)Cu-labeling. Serial PET imaging and biodistribution studies were carried out to evaluate the tumor targeting efficacy and pharmacokinetics in the MDA-MB-231 TNBC model, which expresses high levels of TF on the tumor cells. Blocking studies, histological assessment, as well as RT-PCR were performed to confirm TF specificity of (64)Cu-NOTA-ALT-836-Fab.
ALT-836-Fab was produced with high purity, which exhibited superb TF binding affinity and specificity. Serial PET imaging revealed rapid and persistent tumor uptake of (64)Cu-NOTA-ALT-836-Fab (5.1 ± 0.5 %ID/g at 24 h post-injection; n = 4) and high tumor/muscle ratio (7.0 ± 1.2 at 24 h post-injection; n = 4), several-fold higher than that of the blocking group and tumor models that do not express significant level of TF, which was confirmed by biodistribution studies. TF specificity of the tracer was also validated by histology and RT-PCR.
(64)Cu-NOTA-ALT-836-Fab exhibited prominent tissue factor targeting efficiency in MDA-MB-231 TNBC model. The use of a Fab fragment led to fast tumor uptake and good tissue/muscle ratio, which may be translated into same-day immunoPET imaging in the clinical setting to improve TNBC patient management.
迄今为止，三阴性乳腺癌（TNBC）尚无有效的治疗方法，其临床预后较差。组织因子（TF）表达上调会导致包括TNBC在内的多种实体瘤类型患者的发病率和死亡率增加。我们的目标是利用嵌合抗人TF单克隆抗体ALT - 836的Fab片段进行TNBC的PET成像，其可用于指导未来的TNBC治疗。
通过木瓜蛋白酶酶解产生ALT - 836 - Fab。在进行NOTA偶联和（64）Cu标记之前，进行SDS - PAGE和FACS研究以评估ALT - 836 - Fab的完整性和TF结合亲和力。进行了系列PET成像和生物分布研究，以评估MDA - MB - 231 TNBC模型中的肿瘤靶向疗效和药代动力学，该模型在肿瘤细胞上表达高水平的TF。进行了阻断研究、组织学评估以及RT - PCR以确认（64）Cu - NOTA - ALT - 836 - Fab的TF特异性。
ALT - 836 - Fab的纯度很高，表现出卓越的TF结合亲和力和特异性。系列PET成像显示（64）Cu - NOTA - ALT - 836 - Fab在肿瘤中快速且持续摄取（注射后24小时为5.1±0.5 %ID/g；n = 4），肿瘤/肌肉比值高（注射后24小时为7.0±1.2；n = 4），比阻断组和不表达显著水平TF的肿瘤模型高几倍，生物分布研究证实了这一点。示踪剂的TF特异性也通过组织学和RT - PCR得到验证。
（64）Cu - NOTA - ALT - 836 - Fab在MDA - MB - 231 TNBC模型中表现出显著的组织因子靶向效率。使用Fab片段导致肿瘤快速摄取且组织/肌肉比值良好，这可能转化为临床环境中的当日免疫PET成像，以改善TNBC患者的管理。
