99Tcm直接标记αvβ3受体拮抗剂环形RGD多肽

目的探讨^99Tc^m直接标记αvβ3受体配体——含2个二硫键的精氨酸-甘氨酸-天冬氨酸（RGD）-九肽（RGD-4CK）的可行性和不同标记条件对标记率的影响。方法采用预锡化法^99Tc^m直接标记RGD-4CK，3MM色谱纸层析测定^99Tc^m-RGD-4CK的雕值，计算标记率与比活度。研究各种标记条件对^99Tc^m-RGD-4CK标记率的影响。通过高效液相色谱仪（HPLC）分析，Sep-Pak C18柱层析，进行体外稳定性实验、半胱氨酸置换实验以及血清蛋白结合实验，评价^99Tc^m-RGD-4CK的放射化学性质。结果^99Tc^m-RGD-4CK在以丙酮和V（氨水）：V（乙醇）：V（水）=1：2：5为流动相中的雕值分别为0与0．8～0．9，标记率为（97．8±0．4）％，基础标记条件下的比活度为（11．90±0．05）TBq／mmol。在以下条件下放化纯均〉95％：（1）酒石酸亚锡为150～300μg；（2）预锡化反应pH值为2．0～3．5，温度60℃，保温时间6h以上；（3）^99Tc^mO4^-活度为37～185MBq，体积在200μl内；（4）标记温度为95℃，标记时间30min.^99Tc^m-RGD-4CKHPLC的保留时间与其洗脱液的放射峰基本一致；^99Tc^m-RGD-4CK室温放置6h，放化纯仍〉95％；Sep—Pak C18柱层析测定的^99Tc^m O4^-峰仅比3MM纸层析高0．5％；标记物与300mmol／L半胱氨酸37℃保温1h，^99Tc^m O4^-峰仅增加1．88％；^99Tc^m-RGD-4CK与血清蛋白无明显结合。结论预锡化法^99Tc^m直接标记RGD-4CK方法简便、标记率高，无需分离纯化即可直接应用，还可用于制备冻干品药盒。标记产物^99Tc^m-RGD-4CK具有良好的放射化学性质。     

hNIS基因的组织特异性表达介导肝癌细胞摄取99Tcm

目的探讨人钠／碘同向转运体（hNIS）基因在肝癌细胞中的组织特异性表达介导^99Tc^m摄取的可行性。方法构建鼠白蛋白基因启动子／增强子（mAlb）引导下hNIS和潮酶素共同表达的逆转录病毒载体，该重组逆转录病毒感染大鼠肝癌细胞MH3924A建立稳定表达细胞系，用^125I摄取实验证实hNIS基因的功能表达。建立肝癌移植瘤大鼠模型。在体内和体外水平评价重组肝癌细胞对^99Tc^m的摄取和流出。绘制时间-放射性曲线和体内外放射性分布图。结果重组质粒构建成功。体外培养条件下，hNIS基因稳定转染细胞系摄取^99Tc^m高出野生型肝癌细胞254倍。50μmol／L NaClO3和500μmol／L哇巴因（Ouabain）可分别使MHm AlbhNIS6细胞摄取^99Tc^m降低97．56％和88．20％（P均〈0．01）。而^99Tc^m流出迅速，有效半减期不足2min，应用^99Tc^m／γ相机系统获得了转染肿瘤的清晰图像及定量数据，注射^99Tc^m O4^-后30min，MHmAlbhNIS6细胞形成的移植瘤摄取^99Tc^m比对照组高4倍。结论证实hNIS基因在肝癌细胞中的组织特异性表达介导^99Tc^m摄取；利用^99Tc^m／γ相机系统可无创、简单、定量检测hNIS基因的表达。     

^99Tc^m标记RGD环肽在荷肺腺癌裸鼠中的显像研究

目的制备^99Tc^m标记的含RGD序列的^99Tc^m-联肼尼克酰胺（HYNIC）-c（RGDfK）环肽单体,评价其在整合素表达阳性的肺腺癌严重联合免疫缺陷（SCID）小鼠肿瘤模型中的生物学分布,并进行显像研究。方法（1）以HYNIC为双功能螯合剂,以三羟甲基甘氨酸（tricine）和乙二胺二乙酸为协同配体,采用二步法制备^99Tc^m标记HYNIC—c（RGDfK）,进行细胞结合实验,测定标记物生物学活性;（2）将荷A549肺腺癌模型小鼠分为7组[第7组作为竞争性抑制组,注射显像剂前0．5h先注射HYNIC-c（CRDGfk）100μg],每组5只,经尾静脉注射7．4MBq的^99Tc^m-HYNIC-c（RGDfK）,于注射后0．5,1,2,4,8,12h处死,计算荷A549肺腺癌小鼠模型各脏器％ID／g,同时采用ROI技术研究^99Tc^m-HYNIC—c（RGDfK）在小鼠体内的生物学分布,计算不同时间点的T／NT比值（NT选取肌肉）;（3）取6只荷瘤裸鼠,其中3只为竞争性抑制组,经尾静脉注射7．4MBq的^99Tc^m-HYNIC—c（RGDfK）,于注射后0．5,1,2,4,8,12h进行静态1显像。结果^99Tc^m-HYNIC—c（RGDfK）的标记率〉90％,放化纯〉95％。^99Tc^m-HYNIC—c（RGDfK）与A549肺腺癌细胞特异性结合率最高为36．14％,体内分布实验显示^99Tc^m-HYNIC—c（RGDfK）在肾的摄取率始终高于20％ID／g,注射后0．5h肿瘤％ID／g为10．52±1．48,8h为17．26±2．81,12h为8．93±0．90,竞争性抑制组注射后0．5h为2．29±0．85。通过ROI技术测得T／NT在8h达6．87。注射后1h肿瘤可显影,4～8h显影更清晰。结论^99Tc^m标记HYNIC—c（RGDfK）易于制备,具有良好的靶向性。     

前哨淋巴结显像剂99Tcm-IT-Rituximab的制备及其定位性能

目的研究前哨淋巴结（SLN）显像剂^99Tc^m-亚氨基噻吩（IT）．美罗华（Rituximab）的标记方法及其定位效应。方法采用2-IT作为双功能连接剂，制备^99Tc^m-IT-Rituximab，确定最佳反应条件，评价标记抗体分子完整性及生物活性。观察比较^99Tc^m-IT-Rituximab及^99Tc^m-硫胶体（SC）2种示踪剂在小鼠淋巴结中的定位性能。将^99Tc^m—IT—Rituximab作为显像剂，对10例乳腺癌患者行乳腺癌SLN动态显像。结果2-IT与Rituximab连接的最佳物质的量比为10：1，4℃反应45min后，每分子抗体螯合上的游离巯基数平均为2．1个。IT—Rituximab分子保持完整、免疫活性保留完全。^99Tc^m-IT-Rituximab的标记率〉90％，其与B淋巴瘤细胞株Raji细胞的结合率为69．4％。动物显像结果显示^99Tc^m—IT—Rituximab可清晰定位小鼠SLN，注射后30min～24h SLN均可显影，2h后SLN显影清晰，至24h未见次级淋巴结显影。动物体内分布数据显示^99Tc^m-IT-Rituximab定位性能明显优于^99Tc^m-SC，24h时SLN百分注射剂量率（％ID）为4．49％，次级及第3级淋巴结基本无摄取，24h注射点滞留率为22．14％。结论该标记方法简单，标记率高；^99Tc^m—IT—Rituximab在SLN中定位性能良好，是一种潜在的新型SLN显像剂。     

用99mTc标记胰岛素样生长因子1类似物的方法学研究

目的建立^99mTc标记胰岛素样生长因子1类似物（IGF-1A）的方法，探讨其标记条件。方法通过预锡化法标记IGF-1A，改变标记条件：Tween80的用量从0～10μl，在0．25～6h不同时间点测定标记率，SnCl2·2H2O质量浓度0．75～4g／L，IGF-1A的用量20～100μg，淋洗液的体积10～200μl，加入生理盐水或人血清后1h～24h测定放化纯度，纸层析法测定标记率及胶体水平。结果^99mTc-IGF-1A最高标记率为（94．43±0．75）%，放射性胶体质量分数为（3．47±0．71）％。室温下放置6h标记率为（85．57±2．81）%，加入人血清后放置24h标记率为（54．07±3．86）％。结论上述预锡化法进行^99mTc标记IGF-1A的最佳标记方法为：浓盐酸溶解SnCl2·2H2O后用葡萄糖酸钠溶液配成3g／L，吸取100μl后加入40μl　IGF-1A（2g／L）；300μlNa3PO4和2μl,0．1％Tween80混匀后加入50μl ^99mTc O4新鲜淋洗液；在IGF-1A体系中加入淋洗液体系，混匀，室温下反应0．5h；加入500μl NaH2O4将pH值调节到7左右。该方法简捷且具有较高标记率和良好稳定性。     

小鼠双微体扩增基因反义探针用于荷人前列腺癌裸鼠的显像研究

目的探讨^99Tc^m标记针对小鼠双微体扩增基因（MDM2）mRNA的ASON（MDM2反义探针）用于前列腺癌无创性基因显像的价值。方法以HYNIC为螯合物,对含MDM2mRNA某段序列的ASON、错义寡核苷酸（ASONM）进行^99Tc^m标记,检测标记率及放化纯。建立荷人前列腺癌LNCaP裸鼠肿瘤模型,分为3组（每组10只）,进行^99Tc^m-HYNIC—ASON和^99Tc^mHYNIC—ASONM、^99Tc^mO4^-（对照）肿瘤显像。测量肿瘤／对侧肢体（T／M）比值,采用单因素方差分析对测量数据进行统计学分析。结果ASON的^99Tc^m标记率为（65．15±2．05）％,ASONM的^99Tc^m标记率为（64．93±2．18）％。^99Tc^m-HYNIC—ASON和^99Tc^m-HYNIC—ASONM经纯化后,放化纯均达90％以上。不同探针注射后1、4和10h时,^99Tc^m-HYNIC—ASON组T／M比值分别为3．217±0．125、3．749±0．201和4．028~0．186;^99Tc^m HYNIC—ASONM组分别为1．579±0．128、1．715±1．140和1．683±0．139;对照组分别为2．146±0．132、1．847±0．124和1．528±0．152.^99Tc^m-HYNIC—ASON1、4、10hT／M比值与对照组和错义组差异均有统计学意义（F=213．37～235．41,t=3．527～4．738,均P〈0．01）,而^99Tc^m-HYNIC—ASONM组各T／M比值与对照组差异均无统计学意义（t=2．154、2．287和2．236,均P〉0．05）。结论^99Tc^m标记的MDM2反义探针可在荷人前列腺癌裸鼠模型的肿瘤组织中特异性聚集,可以在早期对前列腺癌进行无创性的基因诊断。     

炎症显像剂^99Tc^m—lomefloxacin的制备及其炎症小鼠模型体内生物学分布

目的建立^99Tc^m标记洛美沙星（lomefloxacin）的方法,评价^99Tc^m-lomefloxacin体外结合能力和炎症小鼠模型体内生物学分布特征。方法制备^99Tc^m-lomefloxacin并用薄层层析法（TLC）进行鉴定。在标记过程中,研究SnCl2·2H2O、lomefloxacin、pH、温度和反应时间等因素对标记结果的影响。测定标记化合物的稳定性、脂水分配系数和体外细菌特异性结合能力。制备小鼠炎症模型30只,用抽签法分为6组,经尾静脉注入^99Tc^m-lomefloxacin,分别于0．5,1,2,4,6h各处死1组小鼠,取出重要脏器组织测量放射性,计算每克组织百分注射剂量率（％ID／g）及炎症肌肉与正常肌肉放射性比值（T／NT）,观察其体内分布特征;另一组行放射自显影,观察显像效果。采用Concise Statistics 10．3软件,组间差异比较行方差分析。结果^99Tc^m-lomefloxacin的标记率和放化纯为97．5％,室温放置6h内标记率和放化纯均〉95％。^99Tc^m-lomefloxacin为脂溶性物质,与金黄色葡萄球菌的体外结合呈现良好的时间和浓度梯度变化。^99Tc^m-lomefloxaein在炎症模型小鼠体内主要分布于炎症组织及肾、肝、脾中,炎症肌肉与对侧正常肌肉的放射性比较,差异有统计学意义（F=9．19,P〈0．05）,T／NT比值峰值为4．07±1．05,给药后2h的显像质量最佳。结论^99Tc^mlomefloxacin标记简单、标记率和放化纯高、稳定性好、体外结合分析和体内生物学分布具有比较理想的炎症显像剂特性。     

99Tcm标记MDM2反义寡核苷酸的实验研究

目的研究^99Tc^m标记小鼠双微体扩增基因（MDM2）mRNA的反义寡核苷酸（ASON）显像诊断乳腺癌的价值。方法以联肼尼克酰胺（HYNIC）为螯合物对ASON、错义寡核苷酸（ASONM）进行^99Tc^m标记，检测标记率、放化纯及其与互补正义链（SON）的结合能力。阳离子脂质体（1ipofectamine 2000）包裹反义探针及错义探针转染人乳腺癌细胞（MCF-7），通过RT-PCR和West-em．blotting法观察乳腺癌细胞MDM2mRNA和蛋白表达。建立荷人乳腺癌MCF-7裸鼠肿瘤模型，分别进行体内分布和肿瘤显像研究。结果ASON的标记率为（57．24-2．98）％（n=5），ASONM的标记率为（56．3±3．01）％（n=5），经纯化后放化纯可达95％以上，且仍保持与互补链的结合能力。不同浓度反义探针作用于乳腺癌细胞24h后，各浓度组MDM2mRNA和蛋白的表达量差异均有统计学意义（P〈0．01），而错义探针对MDM2mRNA和蛋白的表达没有明显影响。体内分布显示，反义及错义探针主要经肝、肾排泄，注射反义探针后，肿瘤／血液和肿瘤／骨骼肌放射性比值随时间的推移而增加。注射反义探针后1h肿瘤显影，肿瘤／对侧肢体放射性比值随时间推移而增加，各时间点错义探针在肿瘤内的聚集量均明显少于反义探针，差异有统计学意义（P〈0．01）。结论^99Tc^m标记的MDM2ASON可在荷人乳腺癌MCF-7裸鼠肿瘤模型的肿瘤组织中特异性聚集，为乳腺癌的特异性诊断提供了一种可能的新方法。     

99Tcm-RGD环肽二聚体的制备及其体内外评价

目的评价^99Tc^m标记的精氨酸-甘氨酸-天冬氨酸（RGD）环肽二聚体E[c（RGDfK）]：的体内外特性及其用于整合素α，B，阳性肿瘤显像的可行性。方法以三羟甲基甘氨酸（tricine）和三苯基膦三磺酸钠（TPPTS）作为协同配体，以联肼尼克酰胺（HYNIC）作为双功能连接剂，采用无亚锡一步法制备^99Tc^m-HYNIC—E[c（RGDfK）]：，通过U87人神经胶质瘤细胞测定其半数抑制浓度（IC50），观察其体外与整合素α，B，受体的结合解离动力学、细胞内化及外化，评价其在荷人神经胶质瘤裸鼠的生物分布。结果^99Tc^m-HYNIC-E[c（RGDfK）]，的标记率〉95％，经Sep-PekC18柱纯化后其放化纯〉99％。与RGD环肽单体C（RGDyK）相比，HYNIC偶联的E[C（RGDfK）]：二聚体具有更高的整合素α，β3亲和力，IC50分别为80．0和9．07nmol／L。细胞实验显示，^99Tc^m-HYNIC—E[C（RGDfK）]：与整合素α，β，结合较快，并迅速被受体介导内化。生物分布实验显示，^99Tc^m -HYNIC—E[C（RGDfK）]：主要经肾脏排泄，在注射后0．5和4h，标记物在肿瘤的每克组织百分注射剂量率（％ID／g）分别为（2．46±0．66）和（3．10±0．35）％ID／g，标记物在肿瘤中的滞留时间足够长。1显像示注射后1h肿瘤清晰可见，注射后4h显像效果更佳。结论^99 Tc^mHYNIC-E[C（RGDfK）]：是一种有前景的用于整合素α，β3，阳性肿瘤显像的显像剂。     

脑灌注显像剂99Tcm-MPBDA的研制与动物实验

目的 研制一种新的SPECT脑灌注显像剂。方法 将化学合成的N2S三齿配体2－巯基丙基－1,2－苯二胺（MPBDA）用^99Tc^m标记：25只昆明种小白鼠静脉注射100μL555-740kBq^99Tc^m-MPBDA进行体内生物分布实验;2只健康恒河猴（4－6kg)静脉快速注入218．3－333MBq^99Tc^mMPBDA或^99Tc^m双半胱乙脂（ECD）后分别即刻连续动态采集和给药后70min行全身显像和脑断层显像;2组小鼠和3只家兔分别进行了急性毒理和热原实验。结果 ^99Tc^m－MPBDA的产率和放化纯度分别大于95％和97％。小鼠体内分布实验结果表明^99Tc^m－MPBDA能在脑内浓聚并具有很好的脑滞留,血清除半衰期小于15min。猴脑动态血流灌注显像示注药后2min脑放射性达高峰,1h脑放射性占2min的83．0％,70min后入脑量高达2．76％ID,略低于^99Tc^m－ECD（2．9％ID）。断层显像可见大脑灰白质对比度好,影像轮廓较清晰。小鼠和兔子注射^99Tc^m－MPBDA后均无毒副反应。结论 研制的^99Tc^m－MPBDA具有^99Tc^m－ECD相近的脑血流灌注显像性能,用于活体安全可靠。     

Comparative in vivo evaluation of technetium and iodine labels on an anti-HER2 affibody for single-photon imaging of HER2 expression in tumors.

In vivo diagnosis with cancer-specific targeting agents that have optimal characteristics for imaging is an important development in treatment planning for cancer patients. Overexpression of the HER2 antigen is high in several types of carcinomas and has predictive and prognostic value, especially for breast cancer. A new type of targeting agent, the Affibody molecule, was described recently. An Affibody dimer, His6-(ZHER2:4)2 (15.4 kDa), binds to HER2 with an affinity of 3 nmol/L and might be used for the imaging of HER2 expression. The use of 99mTc might improve the availability of the labeled conjugate, and Tc(I)-carbonyl chemistry enables the site-specific labeling of the histidine tag on the Affibody molecule. The goals of the present study were to prepare 99mTc-labeled His6-(ZHER2:4)2 and to evaluate its targeting properties compared with the targeting properties of 125I-4-iodobenzoate-His6-(ZHER2:4)2 [125I-His6-(ZHER2:4)2]. METHODS: The labeling of His6-(ZHER2:4)2 with 99mTc was performed with an IsoLink kit. The specificity of 99mTc-His6-(ZHER2:4)2 binding to HER2 was evaluated in vitro with SK-OV-3 ovarian carcinoma cells. The comparative biodistributions of 99mTc-His6-(ZHER2:4)2 and 125I-His6-(ZHER2:4)2 in tumor-bearing BALB/c nu/nu mice were determined. RESULTS: The labeling yield for 99mTc-His6-(ZHER2:4)2 was approximately 60% (50 degrees C), and the radiochemical purity was greater than 97%. The conjugate was stable during storage and under histidine and cysteine challenges and demonstrated receptor-specific binding. The biodistribution study demonstrated tumor-specific uptake levels (percentage injected activity per gram of tissue [%IA/g]) of 2.6 %IA/g for 99mTc-His6-(ZHER2:4)2 and 2.3 %IA/g for 125I-His6-(ZHER2:4)2 at 4 h after injection. Both conjugates provided clear imaging of SK-OV-3 xenografts at 6 h after injection. The tumor-to-nontumor ratios were much more favorable for the radioiodinated Affibody. CONCLUSION: The use of Tc(I)-carbonyl chemistry enabled us to prepare a stable, site-specifically labeled 99mTc-His6-(ZHER2:4)2 conjugate that was able to bind to HER2-expressing cells in vitro and in vivo. The indirectly radioiodinated conjugate provided better tumor-to-liver ratios. The labeling of Affibody molecules with 99mTc should be investigated further.     

^99Tc^m-精氨酸-谷氨酸-苏氨酸在荷人肺癌H1299裸鼠体内分布和显像

目的通过研究^99Tc^m-精氨酸-谷氨酸-苏氨酸（RET）在荷人肺癌H1299裸鼠体内的分布及显像,探讨其用于肺癌显像的可行性。方法采用^99Tc^m-直接法标记RET,再行^99Tc^m-RET与NSCLC细胞H1299的结合实验。荷人肺癌H1299裸鼠尾静脉注射^99Tc^m-RET后,行不同时间（15、30min,1、2．4、8、24、48h组各4只鼠）体内分布实验,分别测定组织放射性摄取（％ID／g）;另取荷瘤鼠3只,注射4．81MBq^99Tc^m-RET后于0．5、1、2、4．5、5、6h行γ显像。结果^99Tc^m-直接标记RET的标记率为（93．15±2．02）％,与H1299细胞的最高结合率为（3．56±0．37）％。荷瘤裸鼠尾静脉注射^99Tc^m-RET后4h肿瘤放射性摄取达（4．96±1．05）％ID／g,肝脏、脾脏有较多放射性摄取[（15．89±1．84）％ID／g和（10．83±1．66）％ID／g];而心脏和血液的放射性摄取较少,相应的T／NT分别为5．70±0．21和12．40±0．11。注射^99Tc^m-RET后4．5～6．0h肿瘤显影清晰。结论^99Tc^m-RET具有亲肺癌的特性,有可能成为一种亲肺癌显像剂。     

脂质体介导^99Tc^m-EGFR mRNA反义肽核酸在荷SKOV3卵巢癌裸鼠体内的分布及显像

目的 评价脂质体介导对^99Tc^m-表皮生长因子受体（EGFR） mRNA反义PNA体外靶细胞摄取、荷瘤裸鼠体内特异显像及生物学分布的影响.方法 利用碱基互补配对原则将带有短肽螯合功能的EGFRmRNA反义PNA与部分互补寡核苷酸杂交,再以配体交换法对反义探针进行^99Tc^m标记,然后以脂质体包裹反义探针,用HPLC法鉴定标记物的标记率.分析脂质体介导及非脂质体介导^99Tc^m-EGFR mRNA反义PNA在体外人卵巢癌SKOV3细胞中的摄取率及滞留率的差别,同时分析两者在荷SKOV3卵巢癌裸鼠模型体内生物学分布及显像情况的差异.数据分析采用两样本t检验（或t＇检验）及Wilcoxon秩和检验.结果 脂质体介导及非脂质体介导^99Tc^m-EGFR mRNA反义PNA6h内标记率均在95％以上.两者在注射后1、2、4、6、12及24 h后的细胞摄取率分别为（28.90±1.12）％、（32.76±1.20）％、（38.20±3.11）％、（41.23±1.60）％、（46.63±1.55）％和（46.78±2.14）％,（3.51±0.39）％、（3.90±0.40）％、（4.69±0.18）％、（5.91±0.26）％、（5.30±0.22）％和（5.39±0.17）％,差异有统计学意义（t＇=47.11～58.67,Z=2.80,均P＜0.05）,两者滞留率差异亦有统计学意义（t＇=7.25～11.55,Z=2.80,均P＜0.05）.注射两探针后1h荷瘤裸鼠肿瘤部位均可显像,但脂质体介导使肿瘤显像更为清楚,肿瘤摄取高峰T/NT由3.95上升至5.02,并明显增加注药后各时间点T/NT（t=3.96,t＇=12.65～ 14.69,Z=2.83～5.29,均P＜0.05）.分子探针主要分布在肿瘤、肾脏及肝脏组织中.肿瘤摄取量随时间逐渐增加,1h时非介导组为（1.49±0.09） ％ID/g,介导后为（2.15±0.21） ％ID/g;6 h时分别为（3.90±0.65） ％ID/g和（5.00±0.10） ％ID/g;脂质体介导后可增加注药后各个时间点的肿瘤/肌肉（t=11.24,t＇=3.96～ 11.94,均P＜0.05）.结论 脂质体介导可以明显促进^99Tc^m-EGFR mRNA反义PNA进入细胞,并提高对EGFR高表达肿瘤的显像效?     

186Re-maSGS-ZHER2:342, a potential Affibody conjugate for systemic therapy of HER2-expressing tumours

Purpose

Affibody molecules are a novel class of tumour-targeting proteins, which combine small size (7 kDa) and picomolar affinities. The Affibody molecule Z_HER2:342 has been suggested for imaging of HER2 expression in order to select patients for trastuzumab therapy. When optimizing chelators for ^99mTc-labelling, we have found that synthetic Z_HER2:342 conjugated with mercaptoacetyl-glycyl-glycyl-glycyl (maGGG) and mercaptoacetyl-glycyl-seryl-glycyl (maGSG) chelators provides relatively low renal uptake of radioactivity and could be suitable for therapy.

Methods

maGGG-Z_HER2:342 and maGSG-Z_HER2:342 were labelled with ¹⁸⁶Re and their biodistribution was studied in normal mice. Dosimetric evaluation and tumour targeting to HER2-overexpressed xenografts (SKOV-3) by ¹⁸⁶Re-maGSG-Z_HER2:342 were studied.

Results

Gluconate-mediated labelling of maGGG-Z_HER2:342 and maGSG-Z_HER2:342 with ¹⁸⁶Re provided a yield of more than 95% within 60 min. The conjugates were stable and demonstrated specific binding to HER2-expressing SKOV-3 cells. Biodistribution in normal mice demonstrated rapid blood clearance, low accumulation of radioactivity in the kidney and other organs, accumulating free perrhenate. Both ¹⁸⁶Re-maGGG-Z_HER2:342 and ¹⁸⁶Re-maGSG-Z_HER2:342 demonstrated lower renal uptake than their ^99mTc-labelled counterparts. ¹⁸⁶Re-maGSG-Z_HER2:342 provided the lowest uptake in healthy tissues. Biodistribution of ¹⁸⁶Re-maGSG-Z_HER2:342 in nude mice bearing SKOV-3 xenografts showed specific targeting of tumours. Tumour uptake 24 h after injection (5.84±0.54%ID/g) exceeded the concentration in blood by more than 500-fold, and uptake in kidneys by about 8-fold. Preliminary dosimetric evaluation showed that dose-to-tumour should exceed dose-to-kidney by approximately 5-fold.

Conclusion

Optimization of chelators improves biodistribution properties of rhenium-labelled small scaffold proteins and enables selection of promising radiotherapeutic agents based on the Affibody molecule.     

新型骨显像剂99Tcm-BIPrDP的制备及生物学性质研究

目的 探讨99Tcm-1-羟基-3-(2-丁基-1H-咪唑-1-基)丙烷-1,1-双膦酸(BIPrDP)用于骨显像的可能性.方法 以2-丁基咪唑为原料,经过3步反应得到BIPrDP.以SnCl2为还原剂,在100℃下沸煮BIPrDP钠盐溶液(50 mg/ml,100μl)与新鲜淋洗的Na99TcmO4溶液(37.0 MBq)混合液30 min,制得99Tcm-BIPrDP.用TLC测定标记率和稳定性.测定99Tcm-BIPrDP在正辛醇-水中的脂水分配系数(log P)和在新鲜肝素抗凝的人血血浆中的血浆蛋白结合率.向ICR小鼠尾静脉注射0.2 ml (7.4 MBq) 99Tcm-BIP(r)DP,分别在5、10、15、30、60、120和240 min时处死小鼠,取其心、肝、脾、肺、肾、骨骼、肌肉、性腺、肠、胃、脑和血液,测其质量及放射性计数,计算％ ID/g及骨放射性与各组织中放射性的比值.计算血药清除动力学方程.对新西兰兔静脉注射99Tcm-BIPrDP后于不同时问显像.用单因素方差分析方法对不同时间各组织％ID/g进行统计学分析.结果 99Tcm-BIPrDP的标记率和放化纯均＞95％,在放置6h后仍具有很好的稳定性.99Tcm-BIPrDP在pH值为7.0和7.4时的log P分别为-2.396 ±0.035和-2.242±0.025,99Tcm-BIPrDP的血浆蛋白结合率为(47.07±0.05)％.在注射99Tcm-BIPrDP 30 min后小鼠骨摄取达到最大值(19.20％ID/g),且能持久,在4h时为18.98％ID/g.在所有的非靶向性组织中,99Tcm-BIPrDP在肾的摄取最高,5min时为24.50％ID/g,4h为5.22％ID/g.其他重要器官普遍摄取较低,在4h时肌肉和脑最低,分别为0.18 ％ID/g和0.03 ％ID/g.在5 min时99Tcm-BIPrDP在血液中的摄取为18.60％ID/g,随后迅速降低,在4h时仅为0.40％ID/g,血药动力学方程为C ＝9.109e-0.262t+2.696e-0.00558t.从药物清除曲线可看出该药在小鼠体内血液清除速率较快,与小鼠体内分布中的血液清除趋势一致.注射99Tcm-BIPrDP后1h即可获得清晰的兔骨显影,在其他软组织中摄取低,清除快.各组织不同时间％ ID/g差异有统计学意义(F=5.65 ～ 859.24,P均＜0.05).结论 99Tcm-BIPrDP制备方便,骨显影清晰,是一种较有潜力的新型骨显像剂.     

Imaging of HER2-expressing tumours using a synthetic Affibody molecule containing the <Superscript>99m</Superscript>Tc-chelating mercaptoacetyl-glycyl-glycyl-glycyl (MAG3) sequence

Purpose Expression of human epidermal growth factor receptor type 2 (HER2) in malignant tumours possesses well-documented prognostic and predictive value. Non-invasive imaging of expression can provide valuable diagnostic information, thereby influencing patient management. Previously, we reported a phage display selection of a small (about 7 kDa) protein, the Affibody molecule Z_HER2:342, which binds HER2 with subnanomolar affinity, and demonstrated the feasibility of targeting of HER2-expressing xenografts using radioiodinated Z_HER2:342. The goal of this study was to develop a method for ^99mTc labelling of Z_HER2:342 using the MAG3 chelator, which was incorporated into Z_HER2:342 using peptide synthesis, and evaluate the targeting properties of the labelled conjugate. Methods MAG3-Z_HER2:342 was assembled using Fmoc/tBu solid phase peptide synthesis. Biochemical characterisation of the agent was performed using RP-HPLC, ESI-MS, biosensor studies and circular dichroism. A procedure for ^99mTc labelling in the presence of sodium/potassium tartrate was established. Tumour targeting was evaluated by biodistribution study and gamma camera imaging in xenograft-bearing mice. Biodistribution of ^99mTc-MAG3-Z_HER2:342 and ¹²⁵I-para-iodobenzoate -Z_HER2:342 was compared 6 h p.i. Results Synthetic MAG3-Z_HER2:342 possessed an affinity of 0.2 nM for HER2 receptors. The peptide was labelled with ^99mTc with an efficiency of about 75–80%. Labelled ^99mTc-MAG3-Z_HER2:342 retained capacity to bind specifically HER2-expressing SKOV-3 cells in vitro. ^99mTc-MAG3-Z_HER2:342 showed specific tumour targeting with a contrast similar to a radioiodinated analogue in mice bearing LS174T xenografts. Gamma camera imaging demonstrated clear and specific visualisation of HER2 expression. Conclusion Incorporation of a mercaptoacetyl-containing chelating sequence during chemical synthesis enabled site-specific ^99mTc labelling of the Z_HER2:342 Affibody molecule with preserved targeting capacity.     

111In-benzyl-DTPA-ZHER2:342, an affibody-based conjugate for in vivo imaging of HER2 expression in malignant tumors.

Data on expression of the HER2 (erbB-2) receptor in breast carcinoma make it possible to select the most efficient treatment. There are strong indications that HER2 expression possesses prognostic and predictive values in ovarian, prostate, and lung carcinomas as well. Visualization of HER2 expression using radionuclide targeting can provide important diagnostic information. The Affibody Z(HER2:342) is a short (approximately 7 kDa) phage-display-selected protein that binds HER2 with an affinity of 22 pmol/L. The goal of this study was to evaluate whether (111)In-labeled HER2:342 can be used for imaging of HER2 overexpression in vivo. METHODS: Z(HER2:342) was labeled with (111)In via isothiocyanate-benzyl-DTPA (DTPA is diethylenetriaminepentaacetic acid) and the conjugate was characterized in vitro and in vivo. RESULTS: (111)In-Benzyl-DTPA-Z(HER2:342) preserved the capacity to bind living HER2-expressing cells specifically. The affinity of In-benzyl-DTPA-Z(HER2:342) to HER2 was 21 pmol/L according to surface plasmon resonance measurements. In nude mice bearing HER2-expressing SKOV-3 xenografts, a tumor uptake of 12% +/- 3% injected activity per gram and a tumor-to-blood ratio of about 100 were obtained 4 h after injection. Tumor uptake in vivo was receptor specific, as it could be blocked with an excess of nonlabeled Z(HER2:342). HER2-expressing xenografts were clearly imaged 4 h after injection using a gamma-camera. CONCLUSION: (111)In-Benzyl-DTPA-Z(HER2:342) is a promising candidate for visualization of HER2 expression in carcinomas, using the single-photon detection technique.     

单克隆抗体4E5的131I标记及131I-4E5对B细胞淋巴瘤细胞的杀伤效应

目的 研究CD80单克隆抗体4E5的131I标记及标记产物131I-4E5对B细胞淋巴瘤细胞的杀伤作用,为B细胞淋巴瘤的放射免疫导向治疗提供实验依据.方法 采用Iodogen法对4E5进行131I标记,以三氯醋酸法测定标记率和放化纯,并对131I-4E5的免疫活性及稳定性进行分析.以四甲基偶氮唑蓝(MTT)比色法观察131I-4E5和4E5对B细胞淋巴瘤Raji细胞的杀伤效应.采用SPSS13.0软件对数据进行单因素方差分析和t检验.结果 131I-4E5的标记率为(78.3±2.4)％,放化纯为(95.7±1.8)％,比活度为0.58 MBq/μg,放射性浓度为3.90×1010 Bq/L.131I-4E5加入血清中放置3d后,放化纯仍＞90％.131I-4E5与Raji细胞的最大结合率为(36.06±2.63)％;131I-4E5对Raji细胞的杀伤作用呈剂量依赖性,高剂量组的细胞杀伤效应明显强于低剂量组:放射性浓度为1.48×1010、7.40×109、3.70×109、1.85×109和9.25×108 Bq/L时,细胞抑制率分别为(52.98±5.19)％、(46.29±2.80)％、(41.05±4.83)％、(33.68±3.79)％和(17.89±2.78)％,F=33.882,P＜0.001;4E5组(质量浓度为20.0、10.0、5.0、2.5和1.25 mg/L)的细胞抑制率分别为(32.98±3.99)％、(30.88±3.98)％、(27.14±2.05)％、(20.35±4.38)％和(8.42±1.05)％,131I-4E5组显著高于4E5组(t=5.290、5.489、4.596、3.986和5.515,P均＜0.05).结论 Iodogen法131I标记4E5标记率和放化纯高,标记物稳定性好;131I-4 E5可与Raji细胞特异性结合并发挥杀伤效应,为以B细胞淋巴瘤CD80为靶点的放射免疫显像及治疗提供了可能性.     

<Superscript>99m</Superscript>Tc-chelator engineering to improve tumour targeting properties of a HER2-specific Affibody molecule

Purpose Monitoring HER2 expression is crucial for selection of breast cancer patients amenable to HER2-targeting therapy. The Affibody molecule Z_HER2:342 binds to HER2 with picomolar affinity and enables specific imaging of HER2 expression. Previously, Z_HER2:342 with the additional N-terminal mercaptoacetyl-glycyl-glycyl-glycyl (maGGG) sequence was labelled with ^99mTc and demonstrated specific targeting of HER2-expressing xenografts. However, hepatobiliary excretion caused high radioactivity accumulation in the abdomen. We investigated whether the biodistribution of Z_HER2:342 can be improved by substituting glycyl residues in the chelating sequence with more hydrophilic seryl residues. Methods The Affibody molecule Z_HER2:342, carrying the chelators mercaptoacetyl-glycyl-seryl-glycyl (maGSG), mercaptoacetyl-glycyl-D-seryl-glycyl [maG(D-S)G] and mercaptoacetyl-seryl-seryl-seryl (maSSS), were prepared by peptide synthesis and labelled with ^99mTc. The differences in the excretion pathways were evaluated in normal mice. The tumour targeting capacity of ^99mTc-maSSS-Z_HER2:342 was studied in nude mice bearing SKOV-3 xenografts and compared with the capacity of radioiodinated Z_HER2:342. Results A shift towards renal excretion was obtained when glycine was substituted with serine in the chelating sequence. The radioactivity in the gastrointestinal tract was reduced threefold for the maSSS conjugate in comparison with the maGGG conjugate 4 h post injection (p.i.). The tumour uptake of ^99mTc-maSSS-Z_HER2:342 was 11.5 ± 0.5% IA/g 4 h p.i., and the tumour-to-blood ratio was 76. The pharmacokinetics and uptake characteristics of technetium-labelled Z_HER2:342 were better than those of radioiodinated Z_HER2:342. Conclusion The introduction of serine residues in the chelator results in better tumour imaging properties of the Affibody molecule Z_HER2:342 compared with glycyl-containing chelators and is favourable for imaging of tumours and metastases in the abdominal area.