Assessment of cyclooxygense-2 expression with 99mTc-labeled celebrex

Cyclooxygenase-2 (COX-2) plays an important role in angiogenesis and cancer progression. Since many tumor cells exhibit COX-2 expression, functional imaging of COX-2 expression using celebrex (CBX, a COX-2 inhibitor) may provide not only a non-invasive, reproducible, quantifiable alternative to biopsies, but it also greatly complements pharmacokinetic studies by correlating clinical responses with biological effects. Moreover, molecular endpoints of anti-COX-2 therapy could also be assessed effectively. This study aimed at measuring uptake of Tc-EC-CBX in COX-2 expression in tumor-bearing animal models. In vitro Western blot analysis and cellular uptake assays were used to examine the feasibility of using Tc-EC-CBX to measure COX-2 activity. Tissue distribution studies of Tc-EC-CBX were evaluated in tumor-bearing rodents at 0.5-4 h. Dosimetric absorption was then estimated. Planar scintigraphy was performed in mice, rats and rabbits bearing tumors. In vitro cellular uptake indicated that cells with higher COX-2 expression (A549 and 13762) had higher uptake of Tc-EC-CBX than lower COX-2 expression (H226). In vivo biodistribution of Tc-EC-CBX in tumor-bearing rodents showed increased tumor:tissue ratios as a function of time. In vitro and biodistribution studies demonstrated the possibility of using Tc-EC-CBX to assess COX-2 expression. Planar images confirmed that the tumors could be visualized with Tc-EC-CBX from 0.5 to 4 h in tumor-bearing animal models. We conclude that Tc-EC-CBX may be useful to assess tumor COX-2 expression. This may be useful in the future for selecting patients for treatment with anti-COX-2 agents.     

Synthesis of [99mTc]ethylenedicysteine-colchicine for evaluation of antiangiogenic effect.

Angiogenesis is in part responsible for tumor growth and the development of metastasis. Radiolabeled angiongenesis inhibitors would be useful to assess tumor microvasculature density. Colchicine (COL), a potent antiangiogenic agent, is known to inhibit microtubule polymerization and cell arrest at metaphase. This study aimed to develop 99mTc-labeled COL (EC-COL) using ethylenedicysteine (EC) as a chelator to assess tumor microvascular density. EC was conjugated to trimethylcolchicinic acid using N-hydroxysuccinimide and 1-ethyl-3-dimethylaminopropyl carbodiimide as coupling agents with a yield of 50-60%. In vivo stability was analyzed in rabbit serum at 0.5-4 h. Tissue distribution and planar imaging studies of [99mTc]EC-COL were evaluated in breast tumor-bearing rats at 0.5, 2 and 4 h. The data was compared to that using [99mTc]EC (control). The radiochemical yield of [99mTc]EC-COL was greater than 95%. [99mTc]EC-COL was stable in rabbit serum. In vivo biodistribution of [99mTc]EC-COL in breast tumor-bearing rats showed increased tumor-to-blood (0.52+/-0.12 to 0.72+/-0.07) and tumor-to-muscle (3.47+/-0.40 to 7.97+/-0.93) ratios as a function of time. Conversely, tumor-to-blood values showed a time-dependent decrease with [99mTc]EC over the same time period. Planar images confirmed that the tumors could be visualized clearly with [99mTc]EC-COL from 0.5 to 4 h. [99mTc]EC-COL may be useful to assess antiangiogenic and therapeutic effects during chemotherapy.     

99mTc-EC-Guanine: Synthesis, Biodistribution, and Tumor Imaging in Animals

Purpose DNA markers are useful in assessing cell proliferation. The purpose of this study was to synthesize ^99mTc-ethylenedicysteine-guanine (EC-Guan) for evaluation of cell proliferation.Methods Tumor cells were incubated with ^99mTc-EC-Guan for cell cycle analysis. Prostate tumor cells that were overexpressing the HSV thymidine kinase gene, or various tumor cells were incubated with ^99mTc-EC-Guan at 0.5–2 h. Thymidine incorporation assays were performed in lung cancer cells incubated with EC-Guan at 0.1–1 mg/well. Tissue distribution, autoradiography, and planar scintigraphy of ^99mTc-EC-Guan and ^99mTc-EC (control) were determined in tumor-bearing rodents at 0.5–4 h.Results Cell culture assays indicated that EC-Guan was incorporated in DNA, and there was no significant uptake difference between HSVTK overexpressed and normal groups. Biodistribution and scintigraphic imaging studies of ^99mTc-EC-Guan showed increased tumor/tissue count density ratios as a function of time.Conclusions Our results indicate that ^99mTc-EC-Guan may be useful as a tumor proliferation imaging agent.     

Biodistribution and scintigraphy of [111In]DTPA-adriamycin in mammary tumor-bearing rats

The aim of this study was to develop an 111In-labeled diethylenetriamine pentaacetic acid-adriamycin (DTPA-ADR) conjugate to image breast cancer. DTPA-ADR was synthesized by reacting adriamycin with DTPA anhydride in the presence of carbonyldiimidazole. After dialysis (MW cut off was 500), the product was freeze-dried (yield 40-50%). An in vitro cell culture study was performed using cells from the 13,762 Fischer rat mammary tumor line. Drug concentrations tested were 0.1-100 microM. Biodistribution studies were conducted at 0.5, 2, 24 and 48 h in mammary tumor-bearing rats (n = 3/time interval, 10 microCi/rat, i.v.) with 13,762 cells (10(5) cells/rat, s.c.). Planar imaging and autoradiograms were obtained at the same intervals. In vitro cell culture assays showed an IC50 of 0.1 +/- 0.01 microM for ADR and 7.2 +/- 0.29 microM for DTPA-ADR, respectively. In biodistribution studies, tumor/blood uptake ratios of [111In]DTPA-ADR at 0.5, 2, 24 and 48 h were 0.55 +/- 0.17, 0.94 +/- 0.17, 3.06 +/- 0.53 and 3.66 +/- 0.35, respectively, whereas those for [111In]DTPA (control) were 1.19 +/- 0.69, 0.84 +/- 0.07, 0.56 +/- 0.10 and 0.60 +/- 0.03, respectively. The tumor uptake value (%ID/g) of [111In]DTPA-ADR at 0.5 h was 0.20 +/- 0.06. Planar images and autoradiograms showed good visability of tumors. Biodistribution, autoradiography and radionuclide imaging of [111In]DTPA-ADR in breast tumor-bearing rats showed that tumor-to-blood ratios increased steadily between 30 min and 48 h. These results indicate that DTPA-ADR, a new cancer imaging agent, might be useful in the diagnosis of breast cancer and may predict a therapeutic effect prior to treatment.     

Synthesis of [18F]Fluoroalanine and [18F]Fluorotamoxifen for Imaging Breast Tumors

Abstract

To develop ligands for imaging breast tumors, [¹⁸F]fluoro analogue of tamoxifen and [¹⁸F]fluoro-alanine were radiosynthesized. In vivo biodistribution studies were performed in mammary tumor-bearing rats. In studies on the biodistribution of an [¹⁸F]fluoro analogue of tamoxifen, tumor uptake decreased when rats were pretreated with diethylstilbestrol (DES), suggesting that tracer uptake in tumors was receptor-mediated. An estrogen receptor assay indicated that tumors have a receptor density of 7.5 fmol/mg protein. Studies of the distribution of [¹⁸F]fluoroalanine in tissue showed that the tumor-to-tissue ratio increases as a function of time. Positron emission tomography (PET) images of tumor-bearing rats demonstrated that tumors can be visualized 1 h after rats are injected with an [¹⁸F]fluoro analogue of tamoxifen. PET imaging of pigs after injection of 10 mCi of [¹⁸F]fluoro analogue of tamoxifen showed uterine uptake that could be blocked by DES (50 mg). The findings suggest that both radiotracers are useful for imaging breast tumors.     

99mTc‐labeled rHuEpo for imaging of the erythropoietin receptor in tumors

To analyze erythropoietin receptor (EpoR) status in tumors, recombinant human erythropoietin (rHuEpo) was labeled with ^99mTc by ^99mTc‐centered 1‐pot synthesis, resulting in high radiochemical purity, stability, and biological activity. Both in vitro cell culture experiments and biodistribution studies of normal rats demonstrated successful EpoR targeting. The biodistribution of labeled rHuEpo in a NCI‐H1975 xenograft model showed tumor accumulation (tumor‐to‐muscle ratio, 4.27 ± 1.77), confirming the expression of active EpoR in tumors. Thus, as a novel single positron emission computerized tomography tracer for the imaging of EpoR expression in vivo, ^99mTc‐rHuEpo is effective for exploring the role of EpoR in cancer growth, metastasis and angiogenesis.     

A novel Tc‐99m and fluorescence‐labeled arginine‐arginine‐leucine‐containing peptide as a multimodal tumor imaging agent in a murine tumor model

We developed a Tc‐99m and TAMRA‐labeled peptide, Tc‐99m arginine‐arginine‐leucine (RRL) peptide (TAMRA‐GHEG‐ECG‐RRL), to target tumor cells and evaluated the diagnostic performance of Tc‐99m TAMRA‐GHEG‐ECG‐RRL as a dual‐modality imaging agent for tumor in a murine model. TAMRA‐GHEG‐ECG‐RRL was synthesized using Fmoc solid‐phase peptide synthesis. Binding affinity and in vitro cellular uptake studies were performed. Gamma camera imaging, biodistribution, and ex vivo imaging studies were performed in murine models with PC‐3 tumors. Tumor tissue slides were prepared and analyzed with immunohistochemistry using confocal microscopy. After radiolabeling procedures with Tc‐99m, Tc‐99m TAMRA‐GHEG‐ECG‐RRL complexes were prepared in high yield (>96%). The K_d of Tc‐99m TAMRA‐GHEG‐ECG‐RRL determined by saturation binding was 41.7 ± 7.8 nM. Confocal microscopy images of PC‐3 cells incubated with TAMRA‐GHEG‐ECG‐RRL showed strong fluorescence in the cytoplasm. Gamma camera imaging revealed substantial uptake of Tc‐99m TAMRA‐GHEG‐ECG‐RRL in tumors. Tumor uptake was effectively blocked by the coinjection of an excess concentration of RRL. Specific uptake of Tc‐99m TAMRA‐GHEG‐ECG‐RRL was confirmed by biodistribution, ex vivo imaging, and immunohistochemistry stain studies. In conclusion, in vivo and in vitro studies revealed substantial uptake of Tc‐99m TAMRA‐GHEG‐ECG‐RRL in tumors. Tc‐99m TAMRA‐GHEG‐ECG‐RRL has potential as a dual‐modality tumor imaging agent.     

Synthesis and evaluation of Tc‐99m and fluorescence‐labeled elastin‐derived peptide,VAPG for multimodal tumor imaging in murine tumor model

We developed a Tc‐99m and fluorescence‐labeled peptide, Tc‐99m TAMRA‐GHEG‐ECG‐VAPG to target tumor cells and evaluated the diagnostic performance as a dual‐modality imaging agent for tumor in a murine model. TAMRA‐GHEG‐ECG‐VAPG was synthesized by using Fmoc solid‐phase peptide synthesis. Radiolabeling of TAMRA‐GHEG‐ECG‐VAPG with Tc‐99m was done by using ligand exchange via tartrate. Binding affinity and in vitro cellular uptake studies were performed. Gamma camera imaging, biodistribution, and ex vivo imaging studies were performed in murine models with SW620 tumors. Tumor tissue slides were prepared and analyzed with immunohistochemistry by using confocal microscopy. After radiolabeling procedures with Tc‐99m, Tc‐99m TAMRA‐GHEG‐ECG‐VAPG complexes were prepared in high yield (>96%). The K_d of Tc‐99m TAMRA‐GHEG‐ECG‐VAPG determined by saturation binding was 16.8 ± 3.6 nM. Confocal microscopy images of SW620 cells incubated with TAMRA‐GHEG‐ECG‐VAPG showed strong fluorescence in the cytoplasm. Gamma camera imaging revealed substantial uptake of Tc‐99m TAMRA‐GHEG‐ECG‐VAPG in tumors. Tumor uptake was effectively blocked by the coinjection of an excess concentration of VAPG. Specific uptake of Tc‐99m TAMRA‐GHEG‐ECG‐VAPG was confirmed by biodistribution, ex vivo imaging, and immunohistochemistry stain studies. In vivo and in vitro studies revealed substantial uptake of Tc‐99m TAMRA‐GHEG‐ECG‐VAPG in tumor cells. Tc‐99m TAMRA‐GHEG‐ECG‐VAPG has potential as a dual‐modality tumor imaging agent.     

99mTc‐labeled tetramer and pentamer of single‐domain antibody for targeting epidermal growth factor receptor in xenografted tumors

The single‐domain antibody EG2 can be fused with right‐handed coiled‐coil (RHCC) and human cartilage oligomeric matrix protein (COMP), to form the multivalent antibodies EG2‐RHCC and EG2‐COMP. We labeled these two antibodies with ^99mTc and assessed their targeting efficiency for epidermal growth factor receptor (EGFR). Cell binding, uptake, efflux, and blocking studies were performed with EGFR high‐ and/or low‐expressing cells with ^99mTc‐labeled EG2‐RHCC or EG2‐COMP. Single photon‐emission computed tomography (SPECT) imaging and biodistribution studies were further carried out. Both ^99mTc‐EG2‐RHCC and ^99mTc‐EG2‐COMP can specially bind to EGFR in vitro. SPECT imaging showed that A431, which expresses high levels of EGFR, was clearly visible 6 h after ^99mTc‐EG2‐COMP injection; however, it was not detectable after administration of ^99mTc‐EG2‐RHCC. Uptake of both antibodies by the non‐EGFR‐secreting OCM‐1 tumors was low. EG2‐COMP shows promise in identifying EGFR over‐expression in tumors; however, EG2‐RHCC may not be suitable for targeting EGFR in vivo.     

Somatostatin receptor-binding peptides suitable for tumor radiotherapy with Re-188 or Re-186. Chemistry and initial biological studies

Somatostatin derivative peptides previously designed for radiodiagnostic purposes (99mTc P829 or 99mTc depreotide) were reoptimized for radiotherapy of tumors with rhenium radioisotopes. An optimized pharmacophore peptide P1839 was derived by in vitro binding affinity assay to AR42J rat pancreatic tumor cell membranes. Peptides with chelating domains and their oxorhenium(V) complexes were tested in vitro for binding to NCI H69 human SCLC tumor membranes. Further optimization entailed radiolabeling with 99mTc and biodistribution in an AR42J xenograft mouse model. Kidney uptake was decreased substantially by removing positively charged residues. Neutral N3S diamide amine thiol chelators with no adjacent positive charges had the best overall properties. Substituting an aromatic amino acid into the chelator approximately doubled the tumor uptake. The final optimized peptide P2045 (39) radiolabeled with 99mTc exhibited increased tumor uptake ( approximately 25 %ID/g at 1.5 h), lower kidney uptake ( approximately 4.8 %ID/g at 1.5 h), and extensive urinary excretion (59 %ID at 1.5 h). Finally, comparison biodistribution studies between 99mTc and 188Re (39) showed a good correlation between the two metal complexes and demonstrated prolonged tumor retention (> or =24 h).     

Noninvasive Assessment of Tumor Hypoxia with 99mTc Labeled Metronidazole

Purpose. The assessment of tumor hypoxia by imaging modality prior to radiation therapy would provide a rational means of selecting patients for treatment with radiosensitizers or bioreductive drugs. This study aimed to develop a ^99mTc-labeled metronidazole (MN) using ethylene-dicysteine (EC) as a chelator and evaluate its potential use to image tumor hypoxia. Methods. EC was conjugated to amino analogue of MN using Sulfo-N-hydroxysuccinimide and l-ethyl-3-(3-dimethylaminopropyl) carbodiimide-HCl as coupling agents, the yield was 55%. Tissue distribution of ^99mTc-EC-MN was determined in breast tumor-bearing rats at 0.5, 2, and 4 hrs. Planar imaging and whole-body autoradiograms were performed. The data was compared to that using ^99mTc-EC (control), [^l8F]fluoromisonidazole (FMISO) and [¹³¹I] iodomisonidazole (IMISO). Results. In vivo biodistribution of ^99mTc-EC-MN in breast tumor-bearing rats showed increased tumor-to-blood and tumor-to-muscle ratios as a function of time. Conversely, tumor-to-blood values showed time-dependent decrease with ^99mTc-EC in the same time period. Planar images and autoradiograms confirmed that the tumors could be visualized clearly with ^99mTc-EC-MN from 0.5 to 4 hrs. There was no significant difference of tumor-to-blood count ratios between ^99mTc-EC-MN and [¹³¹I]IMISO at 2 and 4 hrs postinjection. From 0.5 to 4 hrs, both ^99mTc-EC-MN and [¹³¹I]IMISO have higher tumor-to-muscle ratios compared to [¹⁸]FMISO. Conclusions. It is feasible to use ^99mTc-EC-MN to image tumor hypoxia.     

The effects of linking substituents on the in vivo behavior of site-directed, peptide-based, diagnostic radiopharmaceuticals

A number of human cancers are known to over-express the gastrin-releasing peptide receptor (GRPr) on cell surfaces. The high specificity and affinity of bombesin (BBN), an amphibian analogue of mammalian gastrin-releasing peptide, for the GRPr makes it an ideal candidate for delivery of diagnostic probes, such as 99mTc radiometal, to tumor sites. An optimized targeting agent possesses high tumor uptake with minimal uptake in normal tissues. In this study, 99mTc-targeting vectors of bombesin using various amino acid/aliphatic pharmacokinetic modifiers or linking groups were evaluated to determine the effect of the spacer on receptor binding affinity, internalization/externalization and biodistribution. Conjugates of the general type [DPR-X-BBN] (X = amino acid/aliphatic pharmacokinetic modifier) were synthesized by solid phase peptide synthesis (SPPS) and metallated with either low-valent, radioactive Tc-99m(I) or non-radioactive Re(I)-tricarbonyl precursors. All of the new non-metallated and metallated conjugates were characterized by electrospray ionization mass spectrometry (ESI-MS). Receptor binding affinity, internalization/externalization and biodistribution studies in normal (CF-1) and tumor (human prostate PC-3-bearing mice) are reported. The effectiveness of targeting xenografted PC-3 tumors in rodents for two of the new 99mTc-BBN conjugates is demonstrated herein using small animal single photon emission computed tomography (SPECT).     

环九肽与人乳腺癌MDA-MB-231细胞特异性结合的研究

目的探讨99Tc^m标记分子探针与人乳腺癌MDA-MB-231细胞的特异结合及生物分布。方法：Westernblot分析MDA-MB-231细胞和正常乳腺上皮细胞MCF-10A IL-11受体（IL-11R）蛋白的表达;荧光检测99Tc^m-DTPA-c（CG-RRAGGSC）与乳腺癌细胞的特异性结合及结合位点。18只荷瘤裸鼠随机分为6组（挖-3）,经尾静脉注入0．74MBq（0．1mL）分子探针,不同时间测量其在荷瘤鼠体内生物分布。结果：West-ernblot检测MDA-M13-231细胞IL-11R是MCF-10A细胞的6．7倍;荧光染色证实99Tc^m-DTPA-c（CGRRAGGSC）-FITC特异结合在MDA-MB-231细胞的胞质和胞膜中;乳腺癌细胞IL-11R结合分子探针具饱和性;分子探针在荷瘤鼠体内迅速、持续聚集在瘤体内,4h达峰值（17．63±1．73）％ID／g,其他脏器分布极少,差异有统计学意义（P〈0．05）。结论：MDA-MB-231细胞呈IL-11R高表达,与环九肽具有高亲和力,99Tc^m标记环九肽放射性分子探针体内外能与之靶向特异结合。     

Pharmacokinetics and biodistribution of lonidamine/paclitaxel loaded, EGFR-targeted nanoparticles in an orthotopic animal model of multi-drug resistant breast cancer

The aim of this study was to assess the biodistribution and pharmacokinetics of epidermal growth factor receptor (EGFR)-targeted polymer-blend nanoparticles loaded with the anticancer drugs lonidamine and paclitaxel. Plasma, tumor, and tissue distribution profiles were quantified in an orthotopic animal model of multidrug-resistant breast cancer and were compared to treatment with nontargeted nanoparticles and to treatment with drug solution. A poly(d,l-lactide-co-glycolide)-poly(ethylene glycol)-EGFR targeting peptide (PLGA-PEG-EFGR peptide) construct was synthesized for incorporation in poly(?-caprolactone) particles to achieve active EGFR targeting. An isocratic high-pressure liquid chromatography method was developed to quantify lonidamine and paclitaxel in mice plasma, tumors, and vital organs. The targeted nanoparticles demonstrated a superior pharmacokinetic profile relative to drug solution and nontargeted nanoparticles, particularly for lonidamine delivery. The first target site of accumulation was the liver, followed by the kidneys, and then the tumor mass; maximal tumor accumulation occured at 3 hours after administration. Lonidamine-paclitaxel combination therapy administered via EGFR-targeted polymer-blend nanocarriers may become a viable platform for the future treatment of multidrug-resistant cancer. FROM THE CLINICAL EDITOR: In this study the biodistribution and pharmacokinetics of epidermal growth factor receptor (EGFR)-targeted polymer-blend nanoparticles loaded with lonidamine and paclitaxel were assessed. The targeted nanoparticles demonstrated a superior pharmacokinetic profile relative to drug solution and nontargeted nanoparticles, paving the way to new therapeutic approaches for multidrug-resistant malignancies.     

Biodistribution,Tumor Uptake and Efficacy of 5-FU-Loaded Liposomes: Why Size Matters

Purpose

We have investigated the impact of particle size on the biodistribution, tumor uptake and antiproliferative efficacy of 5-FU-loaded liposomes.

Methods

Three different batches of pegylated liposomes varying in size (i.e., 70, 120 and 250 nm respectively) were tested. The active compounds encapsulated were an equimolar mix of 5-FU, 2′-deoxyinosine and folinic acid. Liposomes were subsequently tested on the human breast cancer model MDA231 cells, a model previously found to be resistant to 5-FU. In vitro, antiproliferative efficacy and microscopy studies of liposomes uptake were carried out. In vivo, comparative biodistribution and efficacy studies were performed in tumor-bearing mice.

Results

Difference in size did not change in vitro antiproliferative activity. Fluorescence-Microscopy studies showed that liposomes were mainly uptaken by tumor cells through a direct internalization process, regardless of their size. Biodistribution profiles in tumor-bearing mice revealed higher accumulation of small liposomes in tumors throughout time as compared with normal and large liposomes (p?in vivo efficacy studies showed at study conclusion that a 68% reduction in tumor size was achieved with small liposomes (p?Conclusion This study suggests that particle size is critical to achieve higher selectivity and efficacy in experimental oncology, including in resistant tumors.     

Preparation and comparative evaluation of 99mTc-labeled 2-iminothiolane modified antibodies and CITC-DTPA immunoconjugates of anti-EGF-receptor antibodies

The use of antibodies as targeting agents for the delivery of radioisotopes to tumors is a promising concept that has received widespread attention since the advent of monoclonal antibody (mAb) technology. The following studies are described in this article: the 99mTc-randiolabeling of 2-iminothiolane (2-IT) modified antibodies and 6-p-isothiocyanatobenzyl- diethylene-triamine penta-acetic acid (CITC-DTPA) immunoconjugates of anti-EGF-receptor antibodies murine ior egf/r3 and humanized h-R3; the analytical methods for quality control of the radiopharmaceutical such as instant thin layer chromatography-silica gel (ITLC-SG); the biological assessment of the radiolabeled molecule using flow cytometry analysis; in vitro stability studies with cysteine and DTPA challenge and the biodistribution studies in 4NMRI xenografted nude mice with U-87 human glioblastoma multiforme and MDA-MB-468 breast cancer cell lines. Labeling efficency of (96.48 +/- 0.70%) (98.42 +/- 0.38%), (94.8 +/- 1.25%) and (96.41 +/- 0.89%) was achieved for 99mTC-2-IT ior efg/r3, 99mTc-CITC-DTPA- ior egf/r3, 99mTc-CITC-DTPA- h-R3 and 99mTc-DIACIM h-R3, respectively. Radiocolloids were less than 2.0% in all cases. The biological activity measured by flow cytometry analysis using the MDA-MB-468 breast cancer cell line showed an immunoreactivity fraction greater than 85% in all concentrations of each immunoconjugate. Challenge studies demonstrated no evidence of transcomplexation of 99mTc to 1.0 mM DTPA for 2-IT modified antibody ior egf/r3 and CITC-DTPA immunoconjugates and only 8.7%, 4.9% and 5.0% of the 99mTc-radiolabeled was transcomplexed to 1.0 mM cysteine after 1 h incubation at 37 degrees C for 2-IT modified antibody ior egf/r3, CITC-DTPA ior egf/r3 and CITC-DTPA h-R3, respectively. Biodistribution studies with 2-IT modified antibodies and CITC-DTPA immunoconjugates indicated high tumor uptake in both cell lines with both immunoconjugates and no accumulation of the radiolabeled antibodies in normal organs.     

Effective delivery of an angiogenesis inhibitor by neovessel-targeted liposomes

Angiogenesis is critical for tumor growth and metastasis, and several angiogenesis inhibitors have been developed for the treatment of cancer. Previously, we identified angiogenic vessel-homing peptide, Ala-Pro-Arg-Pro-Gly (APRPG), by use of a phage-displayed peptide library. APRPG peptide-modified liposomes have been revealed to be useful for the delivery of encapsulated drugs to angiogenic vasculature in tumor-bearing animals. In the present study, to assess the usefulness of APRPG-PEG-modified liposomes as a carrier of angiogenesis inhibitors in vitro and in vivo, we designed and validated APRPG-PEG-modified liposomal angiogenesis inhibitor. SU1498, an inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinase, was successfully encapsulated into the liposomes. APRPG-PEG-modified liposomal SU1498 inhibited VEGF-stimulated endothelial cell proliferation in vitro. Moreover, APRPG-PEG-modified liposomal SU1498 significantly decreased tumor microvessel density in Colon26 NL-17 cell-bearing mice and prolonged the survival time of the mice. These findings suggest that APRPG-PEG-modified liposomes effectively deliver SU1498 to angiogenic endothelial cells in tumors and thus inhibit tumor-induced angiogenesis.     

Bay846, a new irreversible small molecule inhibitor of EGFR and Her2, is highly effective against malignant brain tumor models

The epidermal growth factor receptor (EGFR) pathway is aberrantly activated in tumors and plays a key role in promoting tumor growth. Small molecule inhibitors which bind reversibly to EGFR have demonstrated limited clinical activity. Thus, there is a continued need to develop novel EGFR inhibitors with improved anti-tumor activity. Bay846 is a newly developed small molecule inhibitor that binds irreversibly to the tyrosine kinase domains of EGFR and Her2. The in vitro and in vivo efficacy of Bay846 was tested using a panel of nine human malignant brain tumor (glioma) models. Lapatinib, a reversible inhibitor of EGFR and Her2, was included for comparison. Six glioma cell lines were sensitive to Bay846 treatment. Bay846 strongly suppressed tumor cell growth in vitro by inducing cell lysis/death rather than cell cycle arrest. Consistent with this, Bay846 had potent anti-tumor activity which led to regressions in tumor size. The active, phosphorylated form of EGFR was reduced by Bay846 treatment in vitro and in tumors. Importantly, the efficacy of Bay846 was significantly greater than lapatinib in all assays. Bay846-sensitivity was associated with expression of a wild-type PTEN in conjunction with high levels of an oncogenic EGFR variant (A289V or EGFRvIII). These studies demonstrate that targeting the EGFR pathway with the irreversible inhibitor Bay846 has great potential to increase the efficacy of this cancer therapy.     

Preparation and biodisposition of methoxypolyethylene glycol amine-poly(DL-lactic acid) copolymer nanoparticles loaded with pyrene-ended poly(DL-lactic acid)

A formyl group-ended poly(DL-lactic acid) (PLA-aldehyde), synthesized in the same manner as reported previously, was utilized to produce the polymeric marker for PLA-related nanoparticles. Namely, pyrene-ended poly(DL-lactic acid) (PLA-pyrene) was prepared as a polymeric marker by the reductive amination of PLA-aldehyde and aminopyrene. Methoxypolyethylene glycol amine-poly(DL-lactic acid) block copolymer (PLA-(MeO-PEG) nanoparticles loaded with PLA-pyrene were prepared, and examined on retention of PLA-pyrene in the nanoparticles, and biodisposition in normal and sarcoma-180 solid tumor-bearing mice. PLA-pyrene was retained stably in PLA-(MeO-PEG) nanoparticles in a PBS-ethanol (7:3, v/v) mixture and a plasma-PBS (1:1, v/v) mixture, indicating that PLA-pyrene might be a useful marker of PLA-(MeO-PEG) nanoparticles themselves. After i.v. injection in normal rats, the plasma level of PLA-pyrene was very high for initial 8h, and accumulated gradually into organs, especially spleen and liver. After i.v. injection in tumor-bearing mice, similar biodistribution profiles of PLA-pyrene were observed, and PLA-pyrene was accumulated well in tumor, suggesting that PLA-(MeO-PEG) nanoparticles should be delivered efficiently to solid tumors. It is suggested that PLA-pyrene might be a useful probe of the nanoparticles themselves. In addition, it was demonstrated that PLA-(MeO-PEG) nanoparticles should be a useful drug carrier for passive tumor targeting.     

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.