Rapid optical imaging of EGF receptor expression with a single-chain antibody SNAP-tag fusion protein

Purpose

The epidermal growth factor receptor (EGFR) is overexpressed in several types of cancer and its inhibition can effectively inhibit tumour progression. The purpose of this study was to design an EGFR-specific imaging probe that combines efficient tumour targeting with rapid systemic clearance to facilitate non-invasive assessment of EGFR expression.

Methods

Genetic fusion of a single-chain antibody fragment with the SNAP-tag produced a 48-kDa antibody derivative that can be covalently and site-specifically labelled with substrates containing 0 ⁶-benzylguanine. The EGFR-specific single-chain variable fragment (scFv) fusion protein 425(scFv)SNAP was labelled with the near infrared (NIR) dye BG-747, and its accumulation, specificity and kinetics were monitored using NIR fluorescence imaging in a subcutaneous pancreatic carcinoma xenograft model.

Results

The 425(scFv)SNAP fusion protein accumulates rapidly and specifically at the tumour site. Its small size allows efficient renal clearance and a high tumour to background ratio (TBR) of 33.2?±?6.3 (n?=?4) 10 h after injection. Binding of the labelled antibody was efficiently competed with a 20-fold excess of unlabelled probe, resulting in an average TBR of 6?±?1.35 (n?=?4), which is similar to that obtained with a non-tumour-specific probe (5.44?±?1.92, n?=?4). When compared with a full-length antibody against EGFR (cetuximab), 425(scFv)SNAP-747 showed significantly higher TBRs and complete clearance 72 h post-injection.

Conclusion

The 425(scFv)SNAP fusion protein combines rapid and specific targeting of EGFR-positive tumours with a versatile and robust labelling technique that facilitates the attachment of fluorophores for use in optical imaging. The same approach could be used to couple a chelating agent for use in nuclear imaging.     

Preclinical radioimmunotargeting of folate receptor alpha using the monoclonal antibody conjugate DOTA-MORAb-003

INTRODUCTION: The in vitro and in vivo behavior of the radiolabeled monoclonal antibody MORAb-003 was investigated as a prelude to a clinical trial. METHODS: The cellular retention of 111In- and 131I-labeled MORAb-003 was investigated using IGROV1 and SW620 cells. Biodistribution studies in tumor-bearing mice were performed with the more favorable agent. RESULTS: Five 1,4,7,10-tetraazacyclododecane-N,N',N",N'"-tetraacetic acid (DOTA) molecules were conjugated to MORAb-003 with no apparent loss of immunoreactivity. Radiolabeled MORAb-003 had a high affinity for the folate receptor alpha (FRA) expressed by both IGROV1 and SW620 cells and was found to bind to around 8 x 10(5) and 7 x 10(5) sites/cell, respectively. Both cancer cell lines were found to internalize both 131I- and 111In-labeled MORAb-003, but 111In was retained and 131I was released as iodide. In athymic mice, 111In-DOTA-MORAb-003 was cleared from the blood with a single exponential biological clearance rate of 110 h. The uptake in SW620 tumors was 32+/-5%ID/g after 4 days. The clearance rate of activity from normal organs such as liver, kidney and spleen was similar to the blood clearance and was 5.36%ID/g, 4.03%ID/g and 4.36%ID/g at 1 day postinjection and 2.14%ID/g, 1.65%ID/g and 3.74%ID/g after 8 days, respectively. In a pilot clinical study, the biodistribution and tumor targeting of 111In-MORAb-003 was assessed in three patients undergoing treatment with cold MORAb-003. CONCLUSION: MORAb-003 is an attractive antibody for radioimmunoscintigraphy and possibly radioimmunotherapy of FRA-expressing cancers in addition to its potential direct therapeutic effects.     

Tumor uptake of radioiodinated anti-human pulmonary surfactant-associated protein monoclonal antibody PE10 in nude mice bearing human pulmonary adenocarcinoma in combination with an unlabeled preload

This study assessed the potential use of radioimmunoscintigraphy of pulmonary alveolar Type II cells tumor with the radiolabeled anti-human surfactant-associated protein (SP) monoclonal antibody (MAb) PE 10 in combination with preloads of unlabeled MAb. The in vitro binding of iodine-125 (¹²⁵I)-labeled MAb PE 10 (1 μg), which had a specific radioactivity of 400 MBq/mg, on human pulmonary papillary adenocarcinoma NCI-H441 cells that produced SP was investigated. In NCI-H441 tumor-bearing nude mice, the tumor uptake of ¹²⁵I-MAb PE 10 (5 μg) was examined in combination with preloads of unlabeled MAb PE 10 (0, 5, 10, and 50 μg). An isotype-matched unassociated murine MAb was used as a control both in vitro and in vivo. ¹²⁵I-MAb PE 10 showed specific cell binding compared with ¹²⁵I-control MAb. Tumor uptake of ¹²⁵I-MAb PE 10 in vivo reached a peak of 4.97±0.33% injected dose per gram (%ID/g) at 48 h postinjection. Preloads of 5 and 10 μg unlabeled MAb PE 10 significantly enhanced tumor uptake at 48 h postinjection ( 5.94±0.29% ID/g and 5.72±0.29% ID/g, respectively), whereas preload of 50 μg unlabeled MAb PE 10 significantly decreased tumor uptake ( 2.75±0.32% ID/g) at 48 h. Preload of 5 μg unlabeled MAb PE 10 significantly increased the tumor-to-blood radioactivity ratio at 48 h ( 2.39±0.16). Preloads of unlabeled control MAb did not cause any significant change in tumor uptake. Immunohistochemistry showed the intracellular and pericellular patterns of SP expression in tumor cells. In conclusion, radioimmunoscintigraphy with MAb PE 10 labeled with a γ-emitting radioiodine such as ¹²³I might be a useful means of targeting pulmonary alveolar Type II tumor cells in combination with preloading with an optimal dose of the unlabeled MAb.     

抗伏马菌素B1单克隆抗体的制备和特性

目的建立敏感、特异和快速的针对伏马菌素B1(fumonisin B1, FB1)的酶联免疫吸附试验(enzyme-linked immunosorbent assay ,ELISA)检测方法,形成具有我国自主知识产权的快速检测试剂盒.方法利用B细胞杂交瘤技术,建立能分泌抗伏马菌素B1单克隆抗体的杂交瘤细胞株.结果用伏马菌素B1-牛血清白蛋白(FB1-BSA)偶联物免疫8～10周龄雌性BALB/c小鼠后,取脾细胞与小鼠骨髓瘤细胞系Sp2/0融合,经过3～4次亚克隆建立了1个稳定分泌抗伏马菌素B1毒素抗体的杂交瘤细胞株,命名为5A9.将杂交瘤细胞打入BALB/c小鼠腹腔,获得含抗伏马菌素B1毒素单克隆抗体的腹水,并将腹水用饱和硫酸铵法进行纯化,得到单克隆抗体.该单克隆抗体的Ig亚类为IgG1,腹水中抗体的滴度分别为2.56×106,参考工作浓度为3.2×105.纯化后抗体的IgG含量为10.4 g/L,亲和常数为8.3×10-8 mol/L.该抗体与其他结构类似物无交叉反应,具有较高的特异性.结论制备了具有高特异性和亲和力的抗伏马菌素B1单克隆抗体,初步形成了针对伏马菌素B1的ELISA检测试剂盒.     

Evaluation of a technique for the intraoperative detection of a radiolabelled monoclonal antibody against colorectal cancer

Occult tumour deposits may be localised at operation with a radiation detecting probe following the administration of a radiolabelled monoclonal antibody (MoAb) recognising a tumour-associated antigen. We have recently evaluated the clinical usefulness of this technique in detecting primary colorectal tumours targetted with an indium-111 MoAb. In the present study the physical characteristics of the two detector systems used were investigated; a sodium iodide [NaI(Tl)] scintillation detector and a cadmium telluride (CdTe) semiconductor probe. Limitations of the technique in use have been examined by testing the statistical significance of tumour detection using an abdominal phantom based on the currently available clinical biodistribution data for tumour uptake of radiolabelled MoAAs. The effect of tumour volume, antibody uptake, collimation and counting conditions was examined. Results indicate that tumours of 10 ml volume may be detected with the NaI(TI) probe at the lowest levels of radiolabelled antibody uptake currently reported in the literature but that at higher published levels, lesions as small as 1 ml may be identified with both detector systems. Detector sensitivity and limited antibody specificity restrict the usefulness of the technique, although moderate improvements in tumour uptake may allow the detection of tumour deposits not clinically apparent. The statistical significance criterion used for this study could be an accurate and reliable indicator for tumour detection in vivo. Offprint requests to: W. WaddingtonThis work was presented at the 2nd Annual Meeting of the European Association for Nuclear Medicine, Strasbourg, France, August 28th-September 2nd 1989     

Evaluation of a technique for the intraoperative detection of a radiolabelled monoclonal antibody against colorectal cancer.

Occult tumour deposits may be localised at operation with a radiation detecting probe following the administration of a radiolabelled monoclonal antibody (MoAb) recognising a tumour-associated antigen. We have recently evaluated the clinical usefulness of this technique in detecting primary colorectal tumours targetted with an indium-111 MoAb. In the present study the physical characteristics of the two detector systems used were investigated; a sodium iodide [NaI(Tl)] scintillation detector and a cadmium telluride (CdTe) semiconductor probe. Limitations of the technique in use have been examined by testing the statistical significance of tumour detection using an abdominal phantom based on the currently available clinical biodistribution data for tumour uptake of radiolabelled MoAbs. The effect of tumour volume, antibody uptake, collimation and counting conditions was examined. Results indicate that tumours of 10 ml volume may be detected with the NaI(Tl) probe at the lowest levels of radiolabelled antibody uptake currently reported in the literature but that at higher published levels, lesions as small as 1 ml may be identified with both detector systems. Detector sensitivity and limited antibody specificity restrict the usefulness of the technique, although moderate improvements in tumour uptake may allow the detection of tumour deposits not clinically apparent. The statistical significance criterion used for this study could be an accurate and reliable indicator for tumour detection in vivo.     

Tim-3抗体的生物学活性及应用研究

目的：制备抗人Tim-3单抗并评价其生物学活性,为干预Tim-3表达失调引发的疾病提供实验基础。方法制备重组人Tim-3蛋白,常规方法免疫BALB/c小鼠,筛选出阳性克隆,并对其识别、中和活性进行体内外验证,探讨其作为免疫干预手段的可行性。结果①获得一株能够分泌具有较好结合活性的抗人Tim-3单克隆抗体细胞株（克隆号L3D）,其分泌的免疫球蛋白亚型为IgG2a;②流式实验结果表明,该抗体能够结合人U937细胞上的Tim-3分子,且与小鼠RAW 264．7细胞上Tim-3有一定的交叉结合活性;③该抗体能够阻断Gal-9分子诱导的人THP1细胞凋亡,具有良好的体外中和活性;④体内注射L3D,显示该抗体能够显著加重脓毒血症模型小鼠病情,提高炎性因子的表达水平,显示出其良好的体内中和活性。结论成功制备一株分泌抗人Tim-3抗体的细胞株,其良好的结合及中和活性为基于Tim-3表达异常相关疾病的干预提供了实验基础。     

Radiolabeling of monoclonal antibody against carcinoembryonic antigen with 88Y and biodistribution studies

The biodistribution of the 202 monoclonal antibody against CEA labeled with 88Y by the bicyclic DTPA anhydride method was studied in normal Balb/c mice. The in vitro binding to 1 X 10(7) CO112, LS174T and WiDR colon cancer cells was 21.0, 27.3 and 18.8%, respectively. The binding to an equal number of KM-3 leukemia cells and normal human lymphocytes was 8.9 and 3.2%, respectively. Liver, spleen, kidney and blood were the tissues that showed the highest uptake of radiolabeled antibody in vivo.     

靶向表皮生长因子受体单克隆抗体预定位免疫PET显像的实验研究

目的:采用预定位技术在表皮生长因子受体(EGFR)阳性/阴性荷瘤鼠中探索西妥昔单克隆抗体(简称单抗;Cetuximab)靶向EGFR免疫PET显像的可行性。方法:以反式环辛烯(TCO)- N-羟基琥珀酰亚胺(NHS)修饰Cetuximab获得Cetuximab-TCO。以2,2′-((6-氨基-1-(4,7...     

131I标记的抗肝癌血管内皮细胞单克隆抗体对肝癌治疗的实验研究

目的运用131I标记的抗肝癌血管内皮细胞单克隆抗体,研究靶向血管内皮细胞治疗肝癌的可行性.方法 建立裸小鼠人肝细胞癌动物模型,取30只裸鼠随机分为3组,分别为实验A组、实验B组和对照组,每组各10只.实验A组在接种肝癌细胞的同时,经腹腔注射抗肝癌血管内皮细胞的单克隆抗体,每只200μg/200μl,2次/周;实验B组在接种肝癌细胞的同时,经腹腔注射同剂量的131I标记的抗肝癌血管内皮细胞的单克隆抗体;对照组在接种肝癌细胞的同时,经腹腔注射等量的生理盐水.观察肿瘤的生长情况,计算肿瘤的体积,计算抑瘤率.结果 实验A组的抑瘤率为74.55%,实验B组为86.36%;实验A、B组与对照组比较肿瘤明显受抑(P<0.05).实验B组与实验A组比较显示了明显的放疗作用(P<0.05).HE及免疫组化染色观察证实,经单抗治疗后肿瘤区微血管内血栓形成,血管内皮细胞变性、坏死,血管周围大片肿瘤细胞坏死,瘤内血管密度明显降低.结论 抗肝癌血管内皮细胞单克隆抗体在动物实验中有明显的抑瘤作用,以此抗体为载体与核素相结合,可明显提高治疗肿瘤的疗效.     

Detection of deep venous thrombosis with indium 111-labelled monoclonal antibody against tissue plasminogen activator

The administration of a radiolabelled monoclonal antibody against tissue plasminogen activator allows detection of areas with increased fibrinolytic activity, i. e. those with an active thrombotic lesion. Eight patients with phlebographically verified deep venous thrombosis were examined. At the time of immunoscintigraphy study they were examined receiving anticoagulant therapy. Some 75–85 MBq indium 111-labelled antibody were injected, and scintigrams were obtained after 30 min and after 24 h. The precise site of the thrombus could not be visualized after 30 min due to high background activity, whereas after 24 h it was detectable in all patients. The thrombus/background ratios achieved are twice as high as those observed in a human antifibrin antibody study. These preliminary data suggest a high sensitivity of our t-PA-specific antibody for the detection of active deep venous thrombosis in man, and our antibody seems to offer theoretical advantages over both platelet and fibrin-specific antibodies.     

Detection of deep venous thrombosis with indium 111-labelled monoclonal antibody against tissue plasminogen activator

The administration of a radiolabelled monoclonal antibody against tissue plasminogen activator allows detection of areas with increased fibrinolytic activity, i.e. those with an active thrombotic lesion. Eight patients with phlebographically verified deep venous thrombosis were examined. At the time of immunoscintigraphy study they were examined receiving anticoagulant therapy. Some 75-85 MBq indium 111-labelled antibody were injected, and scintigrams were obtained after 30 min and after 24 h. The precise site of the thrombus could not be visualized after 30 min due to high background activity, whereas after 24 h it was detectable in all patients. The thrombus/background ratios achieved are twice as high as those observed in a human antifibrin antibody study. These preliminary data suggest a high sensitivity of our t-PA-specific antibody for the detection of active deep venous thrombosis in man, and our antibody seems to offer theoretical advantages over both platelet and fibrin-specific antibodies.     

TRAb水平测定在Graves眼病中的临床意义探讨

目的 探讨血清促甲状腺激素受体抗体（TRAb）在Graves眼病发病机制中的作用。 方法 选择初发Graves病患者219例,其中,Graves眼病组121例,无Graves眼病组98例,血清检测甲状腺功能、甲状腺过氧化物酶抗体（TPOAb）、甲状腺球蛋白抗体（TgAb）和TRAb水平,并根据欧洲Graves眼病专家组共识进行Graves眼病临床活动性评分（CAS）和严重程度评估。 结果 Graves眼病组和非Graves眼病组的血清游离三碘甲状腺原氨酸、游离甲状腺素、TPOAb、TgAb和TRAb水平差异均无统计学意义,TRAb水平与Graves眼病病情的严重程度和CAS之间无相关关系。 结论 Graves眼病患者的CAS和病情的严重程度与TRAb水平之间不存在相关关系,因此,TRAb水平与Graves眼病的关系还需要进一步研究。     

分泌抗人IgA单克隆抗体杂交瘤细胞株的建立与鉴定

利用常规杂交瘤技术制备了一株抗人IgA杂交瘤PA_(229) ELISA结果表明,它分泌的抗体与人IgA有特异性反应,而与其它免疫球蛋白重、轻链无交叉反应,为小鼠IgG_1亚类。免疫转印结果只显示针对IgAα链的一条电泳带。用改良ELISA法测得PA_(229)的亲和常数为1.33×10~8L/mol。     

抗PSMA7单克隆抗体的制备和初步鉴定

目的制备抗蛋白酶体α7亚基(PSMA7)的单克隆抗体,为PSMA7的功能研究奠定基础。方法以纯化的重组蛋白PSMA7为抗原免疫BALB/c小鼠,运用杂交瘤技术制备PSMA7单克隆抗体,并用间接ELISA法和Western blot法对单克隆抗体的特性进行鉴定。结果成功建立两株稳定分泌抗PSMA7蛋白的单克隆抗体杂交瘤细胞株,分别命名为B013和B001。检测杂交瘤细胞培养上清抗体效价为1∶128和1∶256,腹水效价为1∶25600和1∶32000。两株单克隆抗体的免疫球蛋白亚类均为IgG1。Westernblot及免疫组化实验证实,两株单克隆抗体均能特异性结合真核细胞内源性PSMA7蛋白。结论成功建立了两株效价高、特异性好的抗PSMA7单克隆抗体杂交瘤细胞,制备的单克隆抗体可用于PSMA7蛋白的鉴定,为其生物学功能研究奠定了基础。     

咪唑啉受体抗血清选择性蛋白的表达、纯化及单克隆抗体制备

目的:表达和纯化咪唑啉受体抗血清选择性蛋白(imidazoline receptor antiserum-selected protein,IRAS protein),制备IRAS蛋白的单克隆抗体.方法:采用基因重组技术在大肠杆菌表达IRAS蛋白;金属镍螯合的Ni-NTA亲和层析柱进行蛋白纯化;杂交瘤技术建立分泌IRAS单克隆抗体的杂交瘤细胞株;以间接ELISA方法筛选分泌特异性IRAS单克隆抗体的杂交瘤细胞;采用蛋白免疫印迹、间接免疫荧光方法鉴定单克隆抗体的特异性.结果:成功表达并纯化了IRAS重组蛋白,纯度达到95%.共筛选出5株分泌IRAS单克隆抗体的杂交瘤细胞株,制备腹水并纯化了IRAS的单克隆抗体,腹水中单克隆抗体效价分别为1∶ 8×106,1∶ 2×106和1∶ 5×106,属于IgG1亚型.该抗体能与原核及真核系统表达的IRAS重组蛋白发生特异性反应,间接免疫荧光显示IRAS蛋白主要定位于细胞质中.结论:建立了稳定分泌IRAS单克隆抗体的杂交瘤细胞株,成功制备了特异性好的IRAS单克隆抗体,为研究IRAS的功能提供了有力的研究工具.     

Magnetic bead-based separation of sperm from buccal epithelial cells using a monoclonal antibody against MOSPD3

Forensic DNA analysis of sexual assault evidence requires unambiguous differentiation of DNA profiles in mixed samples. To investigate the feasibility of magnetic bead-based separation of sperm from cell mixtures using a monoclonal antibody against MOSPD3 (motile sperm domain-containing protein 3), 30 cell samples were prepared by mixing 10⁴ female buccal epithelial cells with sperm cells of varying densities (10³, 10⁴, or 10⁵ cells/mL). Western blot and immunofluorescence assays showed that MOSPD3 was detectable on the membrane of sperm cells, but not in buccal epithelial cells. After biotinylated MOSPD3 antibody was incubated successively with the prepared cell mixtures and avidin-coated magnetic beads, microscopic observation revealed that each sperm cell was bound by two or more magnetic beads, in the head, neck, mid-piece, or flagellum. A full single-source short tandem repeat profile could be obtained in 80 % of mixed samples containing 10³ sperm cells/mL and in all samples containing ≥10⁴ sperm cells/mL. For dried vaginal swab specimens, the rate of successful detection was 100 % in both flocked and cotton swabs preserved for 1 day, 87.5 % in flocked swabs and 40 % in cotton swabs preserved for 3 days, and 40 % in flocked swabs and 16.67 % in cotton swabs preserved for 10 days. Our findings suggest that immunomagnetic bead-based separation is potentially a promising alternative to conventional methods for isolating sperm cells from mixed forensic samples.     

Radioimaging of light chain amyloid with a fibril-reactive monoclonal antibody.

Currently, there are no available means in the United States to document objectively the location and extent of amyloid deposits in patients with systemic forms of amyloidosis. To address this limitation, we have developed a novel diagnostic strategy, namely, the use of a radiolabeled fibril-reactive murine monoclonal antibody (mAb) as an amyloid-specific imaging agent. The goal of this study was to determine the pharmacokinetics, biodistribution, and ability of this reagent to target the type of amyloid that is formed from immunoglobulin light chains, that is, AL. METHODS: Subcutaneous tumors (amyloidomas) were induced in BALB/c mice by injection of human AL fibrils. The IgG1 mAb designated 11-1F4 and an isotype-matched control antibody were radioiodinated, and the pharmacokinetics and localization of these reagents were determined from blood and tissue samples. Amyloidoma-bearing animals that received (125)I- or (124)I-labeled antibodies were imaged by whole-body small-animal SPECT/CT or small-animal PET/CT technology, respectively. RESULTS: Radioiodinated mAb 11-1F4 retained immunoreactivity, as evidenced by its subnanomolar affinity for light chains immobilized on 96-well microtiter plates and for beads conjugated with a light chain-related peptide. Additionally, after intravenous administration, the labeled reagents had the expected biologic half-life of murine IgG1, with monoexponential whole-body clearance kinetics. In the amyloidoma mouse model, (125)I-11-1F4 was predominately localized in the tumors, as demonstrated in biodistribution and autoradiographic analyses. The mean uptake of this reagent, that is, the percentage injected dose per gram of tissue, 72 h after injection was significantly higher for amyloid than for skeletal muscle, spleen, kidney, heart, liver, or other tissue samples. Notably, the accumulation within the amyloidomas of (125)I- or (124)I-11-1F4 was readily visible in the fused small-animal SPECT/CT or small-animal PET/CT images, respectively. CONCLUSION: Our studies demonstrate the amyloid-imaging capability of a radiolabeled fibril-reactive mAb and provide the basis for a clinical trial designed to determine its diagnostic potential in patients with AL amyloidosis and other systemic amyloidoses.