Optimizing radiolabeled engineered anti-p185HER2 antibody fragments for in vivo imaging
Optimizing radiolabeled engineered anti-p185HER2 antibody fragments for in vivo imaging
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DOI：
10.1158/0008-5472.can-04-4472
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发表时间：
2005-07-01
期刊：
影响因子：
11.2
通讯作者：
Wu, AM
中科院分区：
文献类型：
--
作者：
Olafsen, T;Kenanova, VE;Wu, AM
我们最近描述了一种由内化10H8单抗制成的碘化抗p185(HER2)工程抗体片段[mini Body(scFv-C(H)3)2；80 kDa]的体内性质。尽管10H8微体在体外表现出与靶点的良好结合，但在荷有MCF7/HER2乳腺癌肿瘤的裸鼠体内仅获得了适度的肿瘤摄取[每克组织注射剂量(ID/g)5.6+/-1.7%]。在这里，为了提高靶向性，将10H8微体连接到1，4，7，10-四氮杂环十二烷-N，N‘，N“，N”-四乙酸(DOTA)上，进行放射性金属标记，并在体内进行评价。In-111-DOTA 10H8微体的肿瘤摄取率为5.7+/-0.1%ID/g，与放射性碘标记的10H8微体相似。然而，除了预期的肝脏清除外，肾脏的活性出人意料地高(34.0+/-4.0%ID/g)。另一种抗p185(HER2)抗体(曲妥珠单抗；hu4D5vS)也被制成微体。使用铜--DOTA hu4D5v8微体的定量microPET评估的肿瘤摄取率为4.2+/-0.5%ID/g。此外，在非荷瘤小鼠中，in-111-DOTA hu4D5v8微体的肾脏摄取也有类似的升高(28.4+/-6.5%ID/g)。非荷瘤小鼠肾脏的免疫组织化学染色显示近端小管有强烈的特异性染色，肾脏裂解物的Western印迹分析证实存在交叉反应抗原。为了进一步改善肿瘤摄取和正常组织分布，制备了更大的hu4D5v8片段[(scFv-CH2-CH3)(2)；105 kDa]，其被设计为具有快速清除动力学。当用microPET进行评估时，该片段显示出更好的肿瘤靶向性(12.2+/-2.4%TD/g)和降低肾脏摄取(13.1+/-1.5%ID/g)。因此，通过操纵抗p185(HER2)抗体片段的大小和形式，可以降低肾脏的活性，并通过microPET成像来区分移植肾中p185(HER2)的高表达或低表达。
We have recently described the in vivo properties of an iodinated anti-p185(HER2) engineered antibody fragment [minibody (scFv-C(H)3)2; 80 kDa], made from the internalizing 10H8 monoclonal antibody. Although the 10H8 minibody showed excellent binding to the target in vitro, only modest tumor uptake [5.6 +/- 1.7% injected dose per gram (ID/g) of tissue] was achieved in nude mice bearing MCF7/HER2 breast cancer tumors. Here, in an attempt to improve targeting, the 10H8 minibody was conjugated to 1,4,7,10-tetraazacyclododecane-N, N', N", N"-tetraacetic acid (DOTA), radiometal labeled, and evaluated in vivo. The tumor uptake of In-111-DOTA 10H8 minibody was 5.7 +/- 0.1% ID/g, similar to the radioiodinated 10H8 minibody. However, in addition to the expected liver clearance, the kidneys had unexpectedly high activity (34.0 +/- 4.0% ID/g). A minibody derived from a second anti-p185(HER2) antibody (trastuzumab; hu4D5vS) was also made. Tumor uptakes, evaluated by quantitative microPET using Cu-64-DOTA hu4D5v8 minibody, were 4.2 +/- 0.5% ID/g. Furthermore, in non-tumor-bearing mice, In-111-DOTA hu4D5v8 minibody exhibited similar elevated uptake in the kidneys (28.4 +/- 6.5% ID/g). Immunohistochemical staining of kidneys from non-tumor-bearing mice showed strong specific staining of the proximal tubules, and Western blot analysis of kidney lysate confirmed the presence of cross-reactive antigen. To further improve tumor uptake and normal tissue distribution, a larger hu4D5v8 fragment [(scFv-CH2-CH3)(2); 105 kDa] was made, engineered to exhibit rapid clearance kinetics. This fragment, when evaluated by microPET, exhibited improved tumor targeting (12.2 +/- 2.4% TD/g) and reduced kidney uptake (13.1 +/- 1.5% ID/g). Thus, by manipulating the size and format of anti-p185(HER2) antibody fragments, the kidney activity was reduced and high or low expression of p185(HER2) in xenografts could be distinguished by microPET imaging.