Dennis Mark S, Jin Hongkui, Dugger Debra, Yang Renhui, McFarland Leanne, Ogasawara Annie, Williams Simon, Cole Mary J, Ross Sarajane, Schwall Ralph
Department of Antibody Engineering, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
Cancer Res. 2007 Jan 1;67(1):254-61. doi: 10.1158/0008-5472.CAN-06-2531.
Association with albumin as a means to improve biodistribution and tumor deposition of a Fab was investigated using AB.Fab4D5, a bifunctional molecule derived from trastuzumab (HERCEPTIN) capable of binding albumin and tumor antigen HER2 (erbB2) simultaneously. AB.Fab4D5 was compared with trastuzumab and a trastuzumab-derived Fab (Fab4D5) for the ability to target tumors overexpressing HER2 in mouse mammary tumor virus/HER2 allograft models. Biodistribution was monitored using intravital microscopy, histology, and integrated single-photon emission computed tomography/computed tomography analysis. Fab4D5 tumor deposition was characterized by rapid but transient appearance in tumor at 2 h with little retention, followed by rapid accumulation in kidney by 6 h. Trastuzumab was slow to accumulate in tumors and slow to clear from normal tissues, although significant tumor deposition was achieved by 24 h. In contrast, AB.Fab4D5 was observed at 2 h in tumor and its presence was sustained beyond 24 h similar to trastuzumab. Intravital microscopy revealed that at peak tumor accumulation, tumor cell staining by AB.Fab4D5 was more uniform than for Fab4D5 or trastuzumab. Similar tumor deposition was achieved for both AB.Fab4D5 and trastuzumab at 48 h (35.9 +/- 1.8% and 38.2 +/- 3.1% injected dose/g); however, AB.Fab4D5 targeted tumors more rapidly and quickly cleared from blood, leading to a lower overall normal tissue exposure. Importantly, unlike Fab4D5, AB.Fab4D5 did not accumulate in kidney, suggesting that association with albumin leads to an altered route of clearance and metabolism. Rapid targeting, excellent tumor deposition and retention, coupled with high tumor to blood ratios may make AB.Fab an exceptional molecule for imaging and cancer therapy.
使用AB.Fab4D5研究了与白蛋白结合作为改善Fab生物分布和肿瘤沉积的手段，AB.Fab4D5是一种源自曲妥珠单抗（赫赛汀）的双功能分子，能够同时结合白蛋白和肿瘤抗原HER2（erbB2）。在小鼠乳腺肿瘤病毒/HER2同种异体移植模型中，将AB.Fab4D5与曲妥珠单抗和曲妥珠单抗衍生的Fab（Fab4D5）进行比较，以评估它们靶向过表达HER2的肿瘤的能力。使用活体显微镜、组织学和集成单光子发射计算机断层扫描/计算机断层扫描分析监测生物分布。Fab4D5在肿瘤中的沉积特征是在2小时时迅速但短暂地出现在肿瘤中，几乎没有滞留，随后在6小时时迅速在肾脏中积累。曲妥珠单抗在肿瘤中积累缓慢，从正常组织中清除也缓慢，尽管在24小时时实现了显著的肿瘤沉积。相比之下，在2小时时在肿瘤中观察到AB.Fab4D5，其存在持续超过24小时，与曲妥珠单抗相似。活体显微镜显示，在肿瘤积累峰值时，AB.Fab4D5对肿瘤细胞的染色比Fab4D5或曲妥珠单抗更均匀。在48小时时，AB.Fab4D5和曲妥珠单抗的肿瘤沉积相似（注射剂量/克分别为35.9±1.8%和38.2±3.1%）；然而，AB.Fab4D5靶向肿瘤更快，并且更快地从血液中清除，导致总体正常组织暴露较低。重要的是，与Fab4D5不同，AB.Fab4D5不会在肾脏中积累，这表明与白蛋白结合会导致清除和代谢途径的改变。快速靶向、出色的肿瘤沉积和滞留，以及高肿瘤与血液比率，可能使AB.Fab成为成像和癌症治疗的优秀分子。
