99mTc‐labeled DTPA‐colchicine dimer with improved tumor uptake

This work reports the synthesis, radiolabeling, and biological studies of ^99mTc‐diethylene triamine pentaacetic acid (DTPA)‐colchicine dimer in tumor‐bearing mice. The novel colchicine dimer was successfully synthesized by conjugation of DTPA to 2 colchicine biomolecules. The ligand could be labeled by ^99mTc in high yield to get ^99mTc‐DTPA‐colchicine dimer, which was hydrophilic and stable at room temperature. Biodistribution and imaging studies in tumor‐bearing mice showed that ^99mTc‐DTPA‐colchicine dimer accumulated in the tumor with improved uptake and retention. The results indicate the need for synthetic modification of the parent colchicine derivative and the ^99mTc‐chelate with a view to improve the tumor‐targeting efficacy and in vivo kinetic profiles.     

Synthesis, 99mTc‐labeling,and preliminary biological evaluation of DTPA‐melphalan conjugates

Melphalan (MFL) is a typical nitrogen mustard for the treatment of many types of cancer. For the purpose to develop novel ^99mTc‐labeled tumor imaging agents with SPECT, MFL was directly labeled by ^99mTc using diethylene triamine pentacetate acid (DTPA) as bifunctional chelating agent. The novel ligands were successfully synthesized by conjugation of DTPA to MFL to get monosubstituted DTPA‐MFL and bis‐substituted DTPA‐2MFL. Radiolabeling was performed in high yield to get ^99mTc‐DTPA‐MFL and ^99mTc‐DTPA‐2MFL, respectively, which were hydrophilic and stable at room temperature. The high initial tumor uptake with retention, good tumor/muscle ratios, and satisfactory scintigraphic images suggested the potential of ^99mTc‐DTPA‐MFL and ^99mTc‐DTPA‐2MFL for tumor imaging. However, the slow normal tissue clearance would be a great obstacle. Further modification on the linker and/or ^99mTc‐chelate to improve the tumor targeting efficacy and in vivo kinetic profiles is currently in progress.     

99mTc‐labeled NGR‐chlorambucil conjugate, 99mTc‐HYNIC‐CLB‐c(NGR) for targeted chemotherapy and molecular imaging

Targeted delivery of chemotherapeutic drug at the tumor site enhances the efficacy with minimum systemic exposure. Towards this, drugs conjugated with peptides having affinity towards a particular molecular target are recognized as affective agents for targeted chemotherapy. Thus, in the present study, tumor‐homing asparagine‐glycine‐arginine (NGR) peptide ligand was conjugated to DNA alkylating nitrogen mustard, chlorambucil (CLB). The peptide‐drug conjugate (PDC), CLB‐c(NGR), was radiolabeled with ^99mTc‐HYNIC core to trace its pharmacokinetics and biodistribution pattern. In vitro cell‐binding studies of ^99mTc‐HYNIC‐CLB‐c(NGR) were conducted in murine melanoma B16F10 cells. The cytotoxicity studies conducted by incubation of the peptide/drug/PDC with B16F10 cells demonstrated enhanced cytotoxic effect of PDC in comparison to either the peptide or the drug alone. In vivo biodistribution studies in C57BL6 mice bearing melanoma tumor showed maximum tumor uptake at 30 minutes pi (2.45 ± 0.28% ID/g), which reduced to 0.77 ± 0.1% ID /g at 3 hours pi. The radiotracer being hydrophilic cleared rapidly from the heart, lungs, liver, and muscle. The tumor‐to‐blood and tumor‐to‐muscle ratios improved with time. This study opens avenues for conjugation of other targeting peptides with the drug CLB for enhanced toxicity at the diseased site.     

99mTc‐Doxycycline hyclate: a new radiolabeled antibiotic for bacterial infection imaging

Radiolabeled antibiotics are promising radiopharmaceuticals for the precise diagnosis and detection of infectious lesions. Doxycycline Hyclate (DOX) was chosen to investigate new ^99mTc‐labeled antibacterial agent. Ready to use freeze dry kits were formulated with optimum labeling conditions. Human serum stability, sterility, and pyrogenicity of kits were estimated, and gamma scintigraphy, in vivo biodistribution, and histopathological studies with bacterial infected rats were performed. DOX were successfully labeled by ^99mTc with high radiochemical purity, and the labeled compound was stable in human serum. Kits were sterile, pyrogen‐free, and stable up to 6 months. Static images depicted rapid distribution throughout the body and high uptake in bacterial infected thigh muscle. The uptake ratios of radiopharmaceuticals in infected thigh muscle were found above 2 up to 5 h. Five hours after injection, the rats were sacrificed, and biodistribution was determined. Samples of bacterial infected muscle, healthy muscle, blood, liver, spleen, lung, kidney, stomach, intestine, urine and heart were weighed, and the radioactivity was measured by using a gamma counter. The %ID/g of ^99mTc‐DOX was found 0.23 ± 0.06 for infected thigh muscle. According to the imaging, biodistribution, and histopathological studies, the promising characteristics of ^99mTc‐DOX make the new radiopharmaceutical valuable to examine for future studies. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation and comparative evaluation of 99mTc‐HYNIC‐cNGR and 99mTc‐HYNIC‐PEG2‐cNGR as tumor‐targeting molecular imaging probes

The tripeptide sequence asparagine‐glycine‐arginine (NGR) specifically recognizes aminopeptidase N (APN or CD13) receptors highly expressed on tumor cells and vasculature. Thus, NGR peptides can precisely deliver therapeutic and diagnostic compounds to CD13 expressing cancer sites. In this regard, 2 NGR peptide ligands, HYNIC‐c(NGR) and HYNIC‐PEG₂‐c(NGR), were synthesized, radiolabeled with ^99mTc, and evaluated in CD13‐positive human fibrosarcoma HT‐1080 tumor xenografts. The radiotracers, ^99mTc‐HYNIC‐c(NGR) and ^99mTc‐HYNIC‐PEG₂‐c(NGR), could be prepared in approximately 95% radiochemical purity and exhibited excellent in vitro and in vivo stability. The radiotracers were hydrophilic in nature with log P values being ?2.33 ± 0.05 and ?2.61 ± 0.08. The uptake of 2 radiotracers ^99mTc‐HYNIC‐c(NGR) and ^99mTc‐HYNIC‐PEG₂‐c(NGR) was similar in nude mice bearing human fibrosarcoma HT‐1080 tumor xenografts, which was significantly reduced (P < .05) during blocking studies. The 2 radiotracers being hydrophilic cleared rapidly from blood, liver, and intestine and were excreted through renal pathway. The pharmacokinetics of ^99mTc‐labeled HYNIC peptide could not be modulated through introduction of PEG₂ unit, thus posing a challenge for studies with other linkers towards enhanced tumor uptake and retention.     

Gamma scintigraphy and biodistribution of 99mTc‐cefotaxime sodium in preclinical models of bacterial infection and sterile inflammation

^99mTc‐cefotaxime sodium (^99mTc‐CEF) was developed and standardized under varying conditions of reducing and antioxidant agent concentration, pH, radioactivity dose, and reducing agent type. Labeling studies were performed by changing the selected parameters one by one, and optimum labeling conditions were determined. After observing the conditions for maximum labeling efficiency and stability, lyophilized freeze dry kits were prepared accordingly. Simple method for radiolabeling of CEF with ^99mTc has been developed and standardized. Labeling efficiency of ^99mTc‐CEF was assessed by both radio thin‐layer chromatography and radio high‐performance liquid chromatography and found higher than 90%. The labeled compound was found to be stable in saline and human serum up to 24 h. Two different freeze dry kits were developed and evaluated. Based on the data obtained from this study, both products were stable for 6 months with high labeling efficiency. The prepared cold kit was found sterile and pyrogen free. The bacterial infection and sterile inflammation imaging capacity of ^99mTc‐CEF was evaluated. Based on the in vivo studies, ^99mTc‐CEF has higher uptake in infected and inflamed thigh muscle than healthy thigh muscle.     

Multifunctional targeted therapy system based on 99mTc/177Lu‐labeled gold nanoparticles‐Tat(49–57)‐Lys3‐bombesin internalized in nuclei of prostate cancer cells

Radiolabeled gold nanoparticles may function simultaneously as radiotherapy and thermal ablation systems. The gastrin‐releasing peptide receptor (GRP‐r) is overexpressed in prostate cancer, and Lys³‐bombesin is a peptide that binds with high affinity to the GRP‐r. HIV Tat(49–57) is a cell‐penetrating peptide that reaches the DNA. In cancer cells, ¹⁷⁷Lu shows efficient crossfire effect, whereas ^99mTc that is internalized in the cancer cell nuclei acts as an effective system of targeted radiotherapy because of the biological Auger effect. The aim of this research was to evaluate the in vitro potential of ^99mTc‐labeled and ¹⁷⁷Lu‐labeled gold nanoparticles conjugated to Tat(49–57)‐Lys³‐bombesin peptides (^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN) as a plasmonic photothermal therapy and targeted radiotherapy system in PC3 prostate cancer cells. Peptides were conjugated to AuNPs (5 nm) by spontaneous reaction with the thiol group of cysteine (Cys). The effect on PC3 cell viability after laser heating of the AuNP‐Tat‐BN incubated with the cancer cells was conducted using an Nd:YAG laser pulsed for 5 ns at 532 nm (0.65 W/cm²). For the ^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN to be obtained, the ¹⁷⁷Lu‐DOTA‐Gly‐Gly‐Cys and ^99mTc‐HYNIC‐octreotide radiopeptides were first prepared and added simultaneously to a solution of AuNP‐Tat‐BN. ^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN (20 Bq/cell) was incubated with PC3 cells, and the effect on the cell proliferation was evaluated after 3 days. Fluorescence images of ^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN internalized in nuclei of PC3 were also obtained. After laser irradiation, the presence of AuNP‐Tat‐BN caused a significant increase in the temperature of the medium (46.4 vs 39.5 °C of that without AuNP) resulting in a significant decrease in PC3 cell viability down to 1.3%. After treatment with ^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN, the PC3 cell proliferation was inhibited. The nanosystem exhibited properties suitable for plasmonic photothermal therapy and targeted radiotherapy in the treatment of prostate cancer.     

Bioavailability of 99mTc‐Ha‐paclitaxel complex [99mTc‐ONCOFID‐P] in mice using four different administration routes

Paclitaxel, an anti‐tumour drug, shows good results against breast and ovarian cancer. However, its therapeutic response is associated with toxic side‐effects caused by the agent used to dissolve it. Recently paclitaxel was linked to the linear polysaccharide hyaluronic acid (HA), showing good solubility, stabilization, localization and a reduction of cytotoxic side‐effects. To study potential therapeutic applications, HA‐paclitaxel bioconjugate (ONCOFID‐P) was labelled with ^99mTc by the addition of ^99mTc‐pertechnetate, SnCl₂ and sodium gluconate. The reaction mixture was incubated for 90 min at 65°C and purified by size exclusion chromatography. The obtained ^99mTc‐ONCOFID‐P had 100% radiochemical purity and was stable in a phosphate buffer dilution 1:100 for 6 h at 37°C. ^99mTc‐ONCOFID‐P bioavailability studies were carried out in healthy mice using four different administration pathways. The analysis showed that after intravenous administration more than 80% of the injected radiopharmaceutical was found in liver and spleen. Intraperitoneal, intravesical and oral administrations showed that all the ^99mTc‐ONCOFID‐P remained at the administration site. These results demonstrate that ONCOFID‐P administered intravenously could be used for liver metastasis therapy due to its high physiological and receptor‐specific liver uptake, while intravesical, intraperitoneal and oral administration of ONCOFID‐P could be used for local treatment of superficial cancers. Copyright © 2006 John Wiley & Sons, Ltd.     

Radiochemical and biological characteristics of 99mTc‐difloxacin and 99mTc‐pefloxacin for detecting sites of infection

The optimization of the radiolabeling yield of ciprofloxacin analogous, difloxacin and pefloxacin, with ^99mTc was described. At pH 4, difloxacin was labeled with ^99mTc with a labeling yield of 95.6% by adding ^99mTc to 5 mg difloxacin in the presence of 100 µg SnCl₂·2H₂O whereas ^99mTc‐pefloxacin was labeled (98.1%) by adding ^99mTc to 4 mg pefloxacin in the presence of 50 µg SnCl₂·2H₂O. The radiochemical purity for both labeled compounds was evaluated with ITLC and HPLC system. Biological distribution of ^99mTc‐difloxacin and ^99mTc‐pefloxacin was carried out in experimentally induced infection rats, in the left thigh, using Staphylococcus aureus. Both thighs of the rats were dissected and counted and the ratio of bacterial infected thigh/contralateral thigh was then evaluated. T/NT for both ^99mTc‐difloxacin and ^99mTc‐pefloxacin was found to be 5.5±0.5 and 4.9±0.3, respectively, which was higher than that of the commercially available ^99mTc‐ciprofloxacin. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis and pharmacological evaluation of 99mTc‐labeled imidazolyl‐containing diphosphonic acid as a novel bone imaging agent

In order to develop a superior bone imaging agent, a new radiotracer ^99mTc‐1‐hydroxy‐5‐(2‐butyl‐1H‐imidazol‐1‐yl)pentane‐1,1‐diyldiphosphonic acid (BIPeDP) was designed and prepared with good radiochemical yield and stability. The biodistribution in mice shows that ^99mTc‐BIPeDP has high specificity in the skeleton with the maximum uptake of 17.30 ± 0.14 injected dose per gram at 60 min. Kinetics of blood clearance shows that the distribution half‐life (T_1/2α) and elimination half‐life (T_1/2β) of ^99mTc‐BIPeDP are 3.7 and 49.7 min, respectively. An excellent image can be obtained at 1‐h post‐injection with the single photon emission computed tomography bone scanning, which is clearer and quicker than ^99mTc‐zoledronic acid, ^99mTc‐1‐hydroxy‐5‐(1H‐imidazol‐1‐yl)pentane‐1,1‐diyldiphosphonic acid, and ^99mTc‐methylenediphosphonic acid All results indicate that ^99mTc‐BIPeDP holds great potential as a novel promising bone imaging agent. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation and biological evaluation of 99mTc‐stannous fluoride colloid‐labelled‐leucocytes in rats 99mTc‐stannous fluoride‐labelled‐leucocytes in rats

High splenic activity is always visible in ^99mTc‐stannous fluoride (SnF₂)‐labelled‐leucocytes scans. In an attempt to reduce this activity, this study investigated the effect of pre‐injected SnF₂ colloid on the distribution of ^99mTc‐SnF₂ colloid, ^99mTc‐SnF₂‐labelled‐leucocytes, and opsonized ^99mTc‐SnF₂ colloid in rats. The radiopharmaceuticals ^99mTc‐SnF₂ colloid and ^99mTc‐SnF₂‐leucocytes were each found to exhibit identical biodistributions in separate experiments. SnF₂ colloid pre‐injection (26 μg) resulted in reduced splenic uptake of ^99mTc‐SnF₂ colloid (38%) and ^99mTc‐SnF₂‐labelled‐leucocytes (30%), but not for opsonized ^99mTc‐SnF₂ colloid. This indicates that the level of opsonization of radiocolloid is rate limiting rather than the phagocytic capacity of liver and spleen macrophages. There is a low level of ^99mTc‐SnF₂‐labelled‐leucocytes dominated by unopsonized radiocolloid in the ex vivo whole blood dose. Following administration of this dose, free radiocolloid is present in vivo that predominantly localizes in the liver and spleen. This uptake can be challenged with non‐radioactive stannous fluoride colloid pre‐injection, where splenic activity can be significantly reduced by up to 52%. Copyright © 2003 John Wiley & Sons, Ltd.     

Evaluation of a 99mTc‐labelled meso‐bisphenylporphyrin as a tumour image agent

Porphyrins are excellent agents for photodynamic treatment of various types of cancer and also good metal chelators that form highly stable metallo‐complexes with different radionuclides. Therefore, radiolabelled porphyrins could also be potentially used as tumour imaging agents. In this context, the aim of this work was the radiolabelling of meso‐bis[3,4‐bis(carboxymethyleneoxy)phenyl]porphyrin, 2CPP, with Technetium‐99 m (^99mTc) and the evaluation of its radiochemical and biological properties in vitro and in vivo. The labelling procedure was optimized resulting in an efficiency of 92.52 ± 0.48%. The complex ^99mTC‐2CPP remained stable for more than 4 h. The biodistribution showed that ^99mTc‐2CPP is eliminated by gastrointestinal and urinary pathways. The tumour/muscle ratio increases over time, being 3.33 ± 1.22 and 3.55 ± 1.29 in WiDr‐bearing tumours mice and in H1299‐bearing tumours mice, respectively, 6 h post‐injection, showing the tumour specificity of the ^99mTc‐2CPP complex. The favourable tumour/muscle ratio of ^99mTc‐2CPP shows that this complex could potentially be used as tumour imaging agent. Moreover, it could be used to follow the progression or regression of tumours before, during and after the radiotherapy, chemotherapy and photodynamic therapy. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis,radio‐LC‐MS analysis and biological evaluation of 99mTc‐techmazenil

A ^99mTc‐labelled compound with the biological characteristics of flumazenil would be useful for determination of neuronal viability after the onset of a stroke. Therefore, we have derivatized Ro‐15‐3890 (a flumazenil metabolite bearing a carboxylic acid group instead of an ethyl ester) by coupling it with a bisamino bisthiol tetraligand bearing a 3‐hydroxypropyl side chain (3‐hydroxypropyl‐BAT) to enable labelling with technetium‐99m. After purification by RP‐HPLC, the ligand was deprotected and labelled in a ‘one pot’ reaction, yielding a ^99mTc‐BAT‐propylester of Ro‐15‐3890 (^99mTc‐techmazenil). Radio‐LC‐MS analysis of the isolated main peak showed the molecular ion mass (608.0618) of the expected ^99mTc‐techmazenil. The biodistribution of ^99mTc‐techmazenil was investigated in normal mice and indicated that the tracer is cleared from plasma mainly by the hepatobiliary system and shows a very low uptake in brain. In vitro binding studies on mice brain slices indicated that techmazenil does not bind to benzodiazepine receptors. Copyright © 2004 John Wiley & Sons, Ltd.     

Development of 99mTc‐thioflavin‐T derivatives for detection of systemic amyloidosis

In a search for a ^99mTc‐labelled tracer agent for imaging of amyloid plaques in patients with systemic amyloidosis (SA), we have conjugated three bifunctional chelating ligands, namely S‐benzyl‐mercaptoacetyl‐l‐aspartyl(tBu)‐glycine, HYdrazinoNICotinic acid and nitrilotriacetic acid, to the 2‐phenylbenzothiazole core of thioflavin‐T (ThT), which has known affinity for amyloid. The compounds were successfully synthesized and labelled with technetium‐99m. Their structure was confirmed by radio‐LC‐MS analysis. After i.v. injection in normal mice, all three ^99mTc‐labelled ThT derivatives were excreted almost exclusively via liver and intestines. This indicates that the new tracer agents have not the required biokinetics for application as a probe for detection of SA in the abdominal region. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis,separation and biodistribution of 99mTc‐CO‐MIBI complex

^99mTc‐CO‐MIBI was prepared by a two‐step procedure involving the convenient preparation of the [^99mTc(CO)₃(OH₂)₃]⁺ precursor and followed by the substitution of the water molecules by the MIBI (2‐methoxyisobutylisonitrile) ligands. In a second step, the reaction solution was adjusted to different pH values, and then the product, ^99mTc‐CO‐MIBI, was confirmed to be a mixture of two complexes: complex A and complex B, whose labeling yields could be over 90%. The ratio of complex B to the sum of A and B could increase gradually from 0 to 1 when pH was shifted from 3.0 to 9.0. These changes were monitored by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). The two complexes were stable within 8 h at room temperature in vitro. The partition coefficient of the two complexes indicated that there was distinct difference between them. Biodistribution in mice demonstrated that complex B showed better myocardial imaging properties than that of complex A. The heart/liver ratios of complex A, the mixture, and complex B were 1.57, 1.93, and 2.33, respectively, for 30 min post‐injection. The discovery of chemical and biological properties of ^99mTc‐CO‐MIBI would certainly promote the research on a new promising myocardial perfusion‐imaging agent. Copyright © 2004 John Wiley & Sons, Ltd.     

On the 99mTc‐labeling of isoniazid with different 99mTc cores

Recent advances in the chemistry of radiolabeling with ^99mTc such as use of the ^99mTc tricarbonyl and ^99mTc–HYNIC cores have revived interest in ^99mTc‐labeling of small biomolecules and further investigation as potential radiopharmaceuticals. Isoniazid, a drug commonly used for treatment of tuberculosis, has been chosen for the present study. Three distinct strategies were utilized to radiolabel isoniazid with ^99mTc. In the direct labeling protocol, the hydrazino amide functional group of isoniazid was used for ^99mTc‐labeling in the HYNIC sense using tricine and EDDA as co‐ligands. The other strategies of ^99mTc‐labeling involved the derivatization of isoniazid to its N, N‐diacetic acid derivative, which in turn was either used as a tridentate ligand for labeling with the [^99mTc(CO)₃(H₂O)₃]⁺ synthon or directly labeled by the conventional route wherein ^99mTc is in the +3 oxidation state. The complexes prepared in >95% yields were characterized by paper chromatography, thin layer chromatography and HPLC. Comparison of the three approaches showed that maximum specific activity and stability was obtained in the ^99mTc–isoniazid derivative synthesized via the tricarbonyl method. However, in vitro cell‐binding studies indicated that none of the ^99mTc–isoniazid complexes prepared had any appreciable uptake in Mycobacterium tuberculosis. Copyright © 2005 John Wiley & Sons, Ltd.     

In vitro and in silico evaluation of P‐glycoprotein inhibition through 99mTc‐methoxyisobutylisonitrile uptake

P‐glycoprotein (P‐gp) is a multidrug resistance (MDR) transporter with unknown structural details. This macromolecule is normally responsible for extruding xenobiotics from normal cells. Overexpression of P‐gp in tumor cells is a major obstacle in cancer chemotherapy. In this study, human 3D model of P‐gp was built by homology modeling based on mouse P‐gp crystallographic structure and stabilized through 1 ns molecular dynamics (MD) simulation. Stabilized human P‐gp structure was used for flexible docking of 80 drugs into the putative active site of P‐gp. Accordingly, digoxin, itraconazole, risperidone, ketoconazole, prazosin, verapamil, cyclosporine A, and ranitidine were selected for further in vitro assay. Subsequently, cell‐based P‐gp inhibition assay was performed on Caco‐2 cells while ^99mTc‐methoxyisobutylisonitrile (MIBI) was used as a P‐gp efflux substrate for calculating IC50 values. Results of the ^99mTc‐MIBI uptake in drug‐treated Caco‐2 cells were in agreement with the previously reported activities. This study for the first time described the relation between molecular dynamics and flexible docking with cellular experiments using ^99mTc‐MIBI radiotracer for evaluation of potencies of P‐gp inhibitors. Finally, results showed that our radiotracer–cell‐based assay is an accurate and fast screening tool for detecting P‐gp inhibitors and non‐inhibitors in drug development process.     

Evaluation of 99mTc‐immunoglobulins for imaging infection in the rat

Three immunoglobulin molecules were evaluated as infection imaging agents in a rat model of S. aureas infection: ^99mTc‐infliximab, ^99mTc‐human immunoglobulin (HIG) and ^99mTc‐rat immunoglobulin (RIG). Infliximab is a chimeric monoclonal antibody specific for human tumour necrosis factor alpha (TNFα). ^99mTc‐HIG was chosen as an exogenous protein and ^99mTc‐RIG as an endogenous marker. Each immunoglobulin was treated with 2‐mercaptoethanol and the reduced antibody was isolated by size exclusion chromatography. In combination with Sn^II‐methylenediphosphonic acid, cold kit formulations were prepared. Native and reduced infliximab were tested for rat TNFα binding ability in vitro. A focal intramuscular infection of S. aureus (1 × 10⁸ colony forming units) was induced in the left thigh muscle of rats, that developed for 24 h. In separate experiments each tracer was administered by intravenous injection, then whole body scintigraphic imaging and biodistribution studies were performed at 1 and 4 h later. ^99mTc‐infliximab, ^99mTc‐HIG and ^99mTc‐RIG were prepared with ?95% radiochemical purity from stable cold kits. Results from the organ assay gave infected (target) to non‐infected (control) muscle ratios for ^99mTc‐infliximab as 5.7±0.8, 7.1±1.2, ^99mTc‐HIG gave 3.1±1.1, 7.8±1.2, and ^99mTc‐RIG 7.9±0.3, 12.5±1.5 at 1 and 4 h, respectively. Infliximab and Sn^II‐infliximab did not bind to rat TNFα by the in vitro assay. Although lacking specific affinity for TNFα, ^99mTc‐infliximab accumulated at infectious sites in vivo. ^99mTc‐infliximab gave similar infection uptake ratios to ^99mTc‐HIG at 1 and 4 h, but these proteins were inferior in comparison to ^99mTc‐RIG, and is likely to be due to increased clearance associated with the foreign protein structure. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis,quality control,and bio‐evaluation of 99mTc‐cyclophosphamide

Cancer is found to be the leading cause of death worldwide characterized by uncontrolled cell division. Nuclear medicines imaging using radiopharmaceuticals have pronounced potential for the diagnosis and treatment of cancers. Cyclophosphamide (CPH) is an antineoplastic drug which targets selectively cancer cells. In the present work, labeling of CPH with Tc‐99m is performed for diagnostic purpose, which gave labeling yield as high as 99% using 20 μg SnCl₂·2H₂O, 200 μg of ligand at pH 7 for 10 min reaction time at room temperature. The characterization of the prepared complex was performed using ITLC, electrophoresis, and HPLC. In vitro stability was analyzed in the presence of human serum at 37°C which has maximum value of 94 ± 0.5. The biodistribution studies of ^99mTc‐CPH were performed in normal and tumor bearing Swiss Webster mice. The high accumulation of ^99mTc‐CPH was observed in liver and tumours respectively at 4 hr after injection. Biodistribution results revealed that ^99mTc‐CPH may be a potential tumour diagnostic agent simultaneously with chemotherapy.     

Preparation and Evaluation of 99mTc‐labeled anti‐CD11b Antibody Targeting Inflammatory Microenvironment for Colon Cancer Imaging

CD11b, an active constituent of innate immune response highly expressed in myeloid‐derived suppressor cells (MDSCs), can be used as a marker of inflammatory microenvironment, particularly in tumor tissues. In this research, we aimed to fabricate a ^99mTc‐labeled anti‐CD11b antibody as a probe for CD11b⁺ myeloid cells in colon cancer imaging with single‐photon emission computed tomography (SPECT). In situ murine colon tumor model was established in histidine decarboxylase knockout (Hdc^?/?) mice by chemicals induction. ^99mTc‐labeled anti‐CD11b was obtained with labeling yields of over 30% and radiochemical purity of over 95%. Micro‐SPECT/CT scans were performed at 6 h post injection to investigate biodistributions and targeting of the probe. In situ colonic neoplasma as small as 3 mm diameters was clearly identified by imaging; after dissection of the animal, anti‐CD11b immunofluorescence staining was performed to identify infiltration of CD11b+ MDSCs in microenvironment of colonic neoplasms. In addition, the images displayed intense signal from bone marrow and spleen, which indicated the origin and migration of CD11b⁺ MDSCs in vivo, and these results were further proved by flow cytometry analysis. Therefore, ^99mTc‐labeled anti‐CD11b SPECT displayed the potential to facilitate the diagnosis of colon tumor in very early stage via detection of inflammatory microenvironment.