Garousi Javad, Lindbo Sarah, Honarvar Hadis, Velletta Justin, Mitran Bogdan, Altai Mohamed, Orlova Anna, Tolmachev Vladimir, Hober Sophia
Department of Immunology, Genetics and Pathology, Uppsala University , SE-75185 Uppsala, Sweden.
Department of Protein Technology, KTH - Royal Institute of Technology , SE-10691 Stockholm, Sweden.
Bioconjug Chem. 2016 Nov 16;27(11):2678-2688. doi: 10.1021/acs.bioconjchem.6b00465. Epub 2016 Oct 27.
Radionuclide-imaging-based stratification of patients to targeted therapies makes cancer treatment more personalized and therefore more efficient. Albumin-binding domain derived affinity proteins (ADAPTs) constitute a novel group of imaging probes based on the scaffold of an albumin-binding domain (ABD). To evaluate how different compositions of the N-terminal sequence of ADAPTs influence their biodistribution, a series of human epidermal growth factor receptor type 2 (HER2)-binding ADAPT6 derivatives with different N-terminal sequences were created: GCHDANS (2), GC(HE)DANS (3), GCDEAVDANS (4), and GCVDANS(5). These were compared with the parental variant: GCSS(HE)DEAVDANS (1). All variants were site-specifically conjugated with a maleimido-derivative of a DOTA chelator and labeled with In. Binding to HER2-expressing cells in vitro, in vivo biodistribution as well as targeting properties of the new variants were compared with properties of the In-labeled parental ADAPT variant 1 (In-DOTA-1). The composition of the N-terminal sequence had an apparent influence on biodistribution of ADAPT6 in mice. The use of a hexahistidine tag in In-DOTA-2 was associated with elevated hepatic uptake compared to the (HE)-containing counterpart, In-DOTA-3. All new variants without a hexahistidine tag demonstrated lower uptake in blood, lung, spleen, and muscle compared to uptake in the parental variant. The best new variants, In-DOTA-3 and In-DOTA-5, provided tumor uptakes of 14.6 ± 2.4 and 12.5 ± 1.3% ID/g at 4 h after injection, respectively. The tumor uptake of In-DOTA-3 was significantly higher than the uptake of the parental In-DOTA-1 (9.1 ± 2.0% ID/g). The tumor-to-blood ratios of 395 ± 75 and 419 ± 91 at 4 h after injection were obtained for In-DOTA-5 and In-DOTA-3, respectively. In conclusion, the N-terminal sequence composition affects the biodistribution and targeting properties of ADAPT-based imaging probes, and its optimization may improve imaging contrast.
基于放射性核素成像对患者进行分层以实施靶向治疗，可使癌症治疗更具个性化，从而提高治疗效率。白蛋白结合域衍生的亲和蛋白（ADAPTs）构成了一类基于白蛋白结合域（ABD）支架的新型成像探针。为了评估ADAPTs N端序列的不同组成如何影响其生物分布，制备了一系列具有不同N端序列的人表皮生长因子受体2（HER2）结合型ADAPT6衍生物：GCHDANS（2）、GC(HE)DANS（3）、GCDEAVDANS（4）和GCVDANS(5)。将它们与亲本变体GCSS(HE)DEAVDANS（1）进行比较。所有变体均与DOTA螯合剂的马来酰亚胺衍生物进行位点特异性共轭，并用铟标记。将新变体在体外与HER2表达细胞的结合、体内生物分布以及靶向特性与铟标记的亲本ADAPT变体1（In-DOTA-1）的特性进行比较。N端序列的组成对ADAPT6在小鼠体内的生物分布有明显影响。与含（HE）的对应物In-DOTA-3相比，In-DOTA-2中六聚组氨酸标签的使用与肝脏摄取增加有关。与亲本变体相比，所有没有六聚组氨酸标签的新变体在血液、肺、脾脏和肌肉中的摄取均较低。最佳的新变体In-DOTA-3和In-DOTA-5在注射后4小时的肿瘤摄取分别为14.6±2.4和12.5±1.3% ID/g。In-DOTA-3的肿瘤摄取显著高于亲本In-DOTA-1的摄取（9.1±2.0% ID/g）。In-DOTA-5和In-DOTA-3在注射后4小时的肿瘤与血液比值分别为395±75和419±91。总之，N端序列组成影响基于ADAPT的成像探针的生物分布和靶向特性，对其进行优化可能会改善成像对比度。
