Evaluation Efficacy of Rhenium-188-Loaded Micro-particles for Radiotherapy in a Mouse Model of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is one of the leading causes of mortality worldwide. The aim of the present study was to evaluate the distribution and the therapeutic effect of 188Re-Tin-colloid micro-particles in subcutaneous HCC-bearing mice. The synthesis and characterization of micro-particles labeled with the 188Re isotope were performed. The micro-particles were injected into the tumor site subcutaneously in the BNL HCC-bearing mice with three treatment groups, normal saline, 188Re micro-particles, and 188Re-Tin-colloid micro-particles. The results of biodistribution showed that major radioactivity (188Re) of 188Re-Tin-colloid micro-particles (18.69 ± 4.28 %ID/g) remained at the tumor sites, compared with 188Re micro-particles (0.21 ± 0.12 %ID/g), 24 h post injection. Following the injection of 188Re-Tin-colloid micro-particles for 14 days, all BNL tumors in mice were regressed during the observation period. By contrast, all of the mice treated with normal saline or 188Re micro-particles had died by 24 and 28 days, respectively. The 188Re-Tin-colloid micro-particles demonstrated high accumulation and therapeutic potential in the subcutaneous HCC-bearing mice.

Polyethylene glycol-conjugated HER2-targeted peptides as a nuclear imaging probe for HER2-overexpressed gastric cancer detection in vivo.

BACKGROUND: The human epidermal growth factor receptor 2 (HER2) involved proliferation, angiogenesis, and reduced apoptosis in gastric cancer (GC), which is a common target for tumor therapy. HER2 is usually overexpressed in more than 15% GC patients, developing a reliable diagnostic tool for tumor HER2 detection is important. In this study, we attend to use polyethylene glycol (PEG) linked anti-HER2/neu peptide (AHNP-PEG) as a nuclear imaging agent probe for HER2 detection in GC xenograft animal model. METHODS: The HER2 expression of human sera and tissues were detected in GC patients and normal subjects. GC cell lines NCI-N87 (high HER2 levels) and MKN45 (low HER2 levels) were treated with AHNP-PEG to assess the cell viability and HER2 binding ability. The NCI-N87 was treated with AHNP-PEG to observe the level and phosphorylation of HER2. The MKN45 and NCI-N87-induced xenograft mice were intravenous injection with fluorescence labeled AHNP-PEG for detecting in vivo fluorescence imaging properties and biodistribution. The AHNP-PEG was conjugated with diethylenetriaminopentaacetic acid (DTPA) for indium-111 labeling (111In-DTPA-AHNP-PEG). The stability of was assessed in vitro. The imaging properties and biodistribution of 111In-DTPA-AHNP-PEG were observed in NCI-N87-induced xenograft mice. RESULTS: The serum HER2 (sHER2) levels in GC patients were significantly higher than the normal subjects. The sHER2 levels were correlated with the tumor HER2 levels in different stages of GC patients. The AHNP-PEG inhibited the cell growth and down-regulated HER2 phosphorylation in HER2-overexpressed human GC cells (NCI-N87) via specific HER2 interaction of cell surface. In addition, the GC tumor tissues from HER2-postive xenograft mice presented higher HER2 fluorescence imaging as compared to HER2-negative group. The HER2 levels in the tumor tissues were also higher than other organs in NCI-N87-induced xenograft mice. Finally, we further observed that the 111In-DTPA-AHNP-PEG was significantly enhanced in tumor tissues of NCI-N87-induced xenograft mice compared to control. CONCLUSIONS: These findings suggest that the sHER2 measurement may be as a potential tool for detecting HER2 expressions in GC patients. The radioisotope-labeled AHNP-PEG may be useful to apply in GC patients for HER2 nuclear medicine imaging.

pH-Responsive Nanophotosensitizer for an Enhanced Photodynamic Therapy of Colorectal Cancer Overexpressing EGFR.

Photodynamic therapy (PDT) has been shown to kill cancer cells and improve survival and quality of life in cancer patients, and numerous new approaches have been considered for maximizing the efficacy of PDT. In this study, a new multifunctional nanophotosensitizer Ce6/GE11-(pH)micelle was developed to target epidermal growth factor receptor (EGFR) overexpressing colorectal cancer (CRC) cells. This nanophotosensitizer was synthesized using a micelle comprising pH-responsive copolymers (PEGMA-PDPA), biodegradable copolymers (mPEG-PCL), and maleimide-modified biodegradable copolymers (Mal-PEG-PCL) to entrap the potential hydrophobic photosensitizer chlorin e6 (Ce6) and to present EGFR-targeting peptides (GE11) on its surface. In the presence of Ce6/GE11-(pH)micelles, Ce6 uptake by EGFR-overexpressing CRC cells significantly increased due to GE11 specificity. Moreover, Ce6 was released from Ce6/GE11-(pH)micelles in tumor environments, leading to improved elimination of cancer cells in PDT. These results indicate enhanced efficacy of PDT using Ce6/GE11-(pH)micelle, which is a powerful nanophotosensitizer with high potential for application to future PDT for CRC.

Blocking heme oxygenase-1 by zinc protoporphyrin reduces tumor hypoxia-mediated VEGF release and inhibits tumor angiogenesis as a potential therapeutic agent against colorectal cancer.

BACKGROUND: Hypoxia in tumor niche is one of important factors to start regeneration of blood vessels, leading to increase survival, proliferation, and invasion in cancer cells. Under hypoxia microenvironment, furthermore, steadily increased hypoxia-inducible factor -1α (HIF-1α) is observed, and can increase vascular endothelial growth factor (VEGF) expression and promote angiogenesis. Zinc protoporphyrin (ZnPP), a heme oxygenase-1 (HO-1) inhibitor, is potential to inhibit tumor proliferation and progression. However, the mechanism of ZnPP in inhibition of tumor is not completely clear. We hypothesize that ZnPP may modulate HIF-1α through inhibiting HO-1, and then inhibit angiogenesis and tumor progression. This study aimed to dissect the mechanism of ZnPP in tumor suppression. RESULTS: We observed the amount of VEGF was increased in the sera of the colorectal cancer (CRC) patients (n = 34, p < 0.05). Furthermore, increased VEGF expression was also measured in colorectal cancer cells, HCT-15, culturing under mimicking hypoxic condition. It suggested that hypoxia induced VEGF production from cancer cells. VEGF production was significantly reduced from HCT-15 cells after exposure to HIF-1α inhibitor KC7F2, suggesting that HIF-1α regulated VEGF production. Moreover, we observed that the HO-1 inhibitor ZnPP inhibited the expressions of HIF-1α and VEGF coupled with cell proliferations of HCT-15 cells, suggesting that ZnPP blocked HIF-1α expression, and then inhibited the consequent VEGF production. In the xenograft model, we also observed that the animals exposed to ZnPP displayed much smaller tumor nodules and less degree of angiogenesis with decreased expression of the angiogenesis marker, αvß3 integrin, compared to that in normal control. CONCLUSIONS: This study demonstrated that VEGF level in serum was elevated in the patients with CRC. The HO-1 inhibitor, ZnPP, possessed the properties of anti-tumor agent by decreasing HIF-1α levels, blocking VEGF production, impairing tumor angiogenesis, and inhibiting tumor growth.

High performance liquid chromatography-tandem mass spectrometry method for ex vivo metabolic studies of a rhenium-labeled radiopharmaceutical for liver cancer.

The radio-isotope rhenium-labeled N-[2-(triphenylmethyl)thioethyl]-3-aza-19-ethyloxycarbonyl-3-[2-(triphenylmethyl)thioethyl] octadecanoate) ligand (188Re-MN-16ET) is a novel therapeutic agent under preclinical evaluation for hepatoma. A reversed-phase high performance liquid chromatography coupled with a tandem mass spectrometric analysis method and diode array detector (DAD) involving a T type splitter was developed to characterize this pharmaceutical in rat liver tissue solution and determine its biotransformation rate. The separation was accomplished on a C18 column (chromolith silica, 4.6 mm x 100 mm) using an acetonitrile-ammonium acetate buffer gradient as the mobile phase. The detection was achieved by DAD set at 250nm and tandem mass spectrometry using electrospray ionization in the positive ion mode. Re-MN-16ET displayed a retention time of 23.2 min and a transition ion pair corresponding to m/z677 --> 631 for multiple reaction monitoring. Its biotransformation reaction in rat liver homogenate proceeded for 90 min in a 37°C water bath. The characterization was conducted using aliquots that were extracted and concentrated from the reaction mixture for various incubation times. Re-MN-16ET exhibited a biotransformation half-life (t1/2) of 8-9 min in liver tissue solution and was almost completely exhausted after 90 min. Two of its metabolites, consisting of the Re-labeled carboxylic acid derivative, predominately, and its corresponding demetallized disulfide ligand were found in the liver homogenate, providing a metabolism pathway for the radio-pharmaceutical.

Development of in situ forming thermosensitive hydrogel for radiotherapy combined with chemotherapy in a mouse model of hepatocellular carcinoma.

This study evaluated a system for local cancer radiotherapy combined with chemotherapy. The delivery system is a thermosensitive hydrogel containing a therapeutic radionuclide ((188)Re-Tin colloid) and a chemotherapeutic drug (liposomal doxorubicin). The thermosensitive PCL-PEG-PCL copolymer was designed to spontaneously undergo a sol-gel phase transition in response to temperature, remaining liquid at room temperature and rapidly forming a gel at body temperature. A scanning electron microscope was used to observe the microstructure of the fully loaded hydrogel. Release of radionuclide and doxorubicin from the hydrogel was slow, and the system tended to remain stable for at least 10 days. After the intratumoral administration of Lipo-Dox/(188)Re-Tin hydrogel in mice with hepatocellular carcinoma (HCC), its retention by the tumor, spatiotemporal distribution, and therapeutic effect were evaluated. The residence time in the tumor was significantly longer for (188)Re-Tin loaded hydrogel than for Na (188)Re perrhenate (Na (188)ReO4). The hydrogel after thermal transition kept the radionuclide inside the tumor, whereas free (188)Re perrhenate ((188)ReO4) diffused quickly from the tumor. The tumor growth was more profoundly inhibited by treatment with Lipo-Dox/(188)Re-Tin hydrogel (with up to 80% regression of well-established tumors on day 32) than treatment with either (188)Re-Tin hydrogel or Lipo-Dox hydrogel. Therefore, this injectable and biodegradable hydrogel may offer the advantage of focusing radiotherapy and chemotherapy locally to maximize their effects on hepatocellular carcinoma.

Development of thermosensitive poly(n-isopropylacrylamide-co-((2-dimethylamino) ethyl methacrylate))-based nanoparticles for controlled drug release.

Thermosensitive nanoparticles based on poly(N-isopropylacrylamide-co-((2-dimethylamino)ethylmethacrylate)) (poly(NIPA-co-DMAEMA)) copolymers were successfully fabricated by free radical polymerization. The lower critical solution temperature (LCST) of the synthesized nanoparticles was 41 °C and a temperature above which would cause the nanoparticles to undergo a volume phase transition from 140 to 100 nm, which could result in the expulsion of encapsulated drugs. Therefore, we used the poly(NIPA-co-DMAEMA) nanoparticles as a carrier for the controlled release of a hydrophobic anticancer agent, 7-ethyl-10-hydroxy-camptothecin (SN-38). The encapsulation efficiency and loading content of SN-38-loaded nanoparticles at an SN-38/poly(NIPA-co-DMAEMA) ratio of 1/10 (D/P = 1/10) were about 80% and 6.293%, respectively. Moreover, the release profile of SN-38-loaded nanoparticles revealed that the release rate at 42 °C (above LCST) was higher than that at 37 °C (below LCST), which demonstrated that the release of SN-38 could be controlled by increasing the temperature. The cytotoxicity of the SN-38-loaded poly(NIPA-co-DMAEMA) nanoparticles was investigated in human colon cancer cells (HT-29) to compare with the treatment of an anticancer drug, Irinotecan(®) (CPT-11). The antitumor efficacy evaluated in a C26 murine colon tumor model showed that the SN-38-loaded nanoparticles in combination with hyperthermia therapy efficiently suppressed tumor growth. The results indicate that these thermo-responsive nanoparticles are potential carriers for controlled drug delivery.

In vivo MR/optical imaging for gastrin releasing peptide receptor of prostate cancer tumor using Gd-TTDA-NP-BN-Cy5.5.

Magnetic resonance imaging (MRI) has become the leading imaging tool for providing fine anatomical and physiology details. Optical imaging is offering a sensitive and specific method for in vivo molecular imaging of targeting molecules. The goal of this study is to design, synthesize, and characterize a new target-specific dual contrast agent for MR and optical imaging. Hence, [Gd(TTDA-NP)(H(2)O)](2-) was prepared and characterized. In addition, an 8-amino acid Bombesin analogue (BN) peptide substrate, which can target prostate, breast, and colon cancer, was synthesized by solid-phase peptide synthesis and subsequently conjugated with [Gd(TTDA-NP)(H(2)O)](2-) to form BN conjugated Gd-TTDA-NP-BN. The water-exchange rate (k(ex)(298)) for [Gd(TTDA-NP)(H(2)O)](2-) (110×10(6)s(-1)) is significantly higher than that of [Gd(DTPA)(H(2)O)](2-) complex and the rotational correlation time (τ(R)) for [Gd(TTDA-NP)(H(2)O)](2-) (145ps) is also higher than those of [Gd(TTDA)(H(2)O)](2-) (104ps) and [Gd(DTPA)(H(2)O)](2-) (103ps). The Gd-TTDA-NP-BN shows remarkable high relaxivity (7.12mM(-1)s(-1)) comparing to that of [Gd(TTDA-NP)(H(2)O)](2-). The fluorescence studies showed that the Gd-TTDA-NP-BN could efficiently enter PC-3 cells. Additionally, the human cancer cells xenografts using Gd-TTDA-NP-BN-Cy5.5 as an optical imaging probe clearly visualized subcutaneous PC-3 tumor and demonstrated its targeting ability to the gastrin releasing peptide (GRP) receptor overexpression. Furthermore, the biodistribution studies demonstrated significantly high tumor uptake (25.97±1.07% ID/g) and high tumor-to-normal tissue ratios at one hour post-injection of Gd-TTDA-NP-BN-Cy5.5 in the animal model. These results suggest that the Gd-TTDA-NP-BN-Cy5.5 is a superior probe for in vivo optical imaging. Importantly, the MR imaging studies showed notable signal enhancement (44.9±4.2%) on the tumor, indicating a high level accumulation of the contrast agent within the PC-3 tumor sites. Hence, targeting of prostate cancer cells was observed under in vitro and in vivo MR imaging studies using Gd-TTDA-NP-BN contrast agent. We conclude that Gd-TTDA-NP-BN and Gd-TTDA-NP-BN-Cy5.5 can be potentially used as the contrast agents for targeting GRP receptor overexpressing cells and tumors.

Identification of a new peptide for fibrosarcoma tumor targeting and imaging in vivo.

A 12-mer amino acid peptide SATTHYRLQAAN, denominated TK4, was isolated from a phage-display library with fibrosarcoma tumor-binding activity. In vivo biodistribution analysis of TK4-displaying phage showed a significant increased phage titer in implanted tumor up to 10-fold in comparison with normal tissues after systemic administration in mouse. Competition assay confirmed that the binding of TK4-phage to tumor cells depends on the TK4 peptide. Intravenous injection of (131)I-labeled synthetic TK4 peptide in mice showed a tumor retention of 3.3% and 2.7% ID/g at 1- and 4-hour postinjection, respectively. Tumor-to-muscle ratio was 1.1, 5.7, and 3.2 at 1-, 4-, and 24-hour, respectively, and tumors were imaged on a digital γ-camera at 4-hour postinjection. The present data suggest that TK4 holds promise as a lead structure for tumor targeting, and it could be further applied in the development of diagnostic or therapeutic agent.

Development of pH sensitive 2-(diisopropylamino)ethyl methacrylate based nanoparticles for photodynamic therapy.

Photodynamic therapy is an effective treatment for tumors that involves the administration of light-activated photosensitizers. However, most photosensitizers are insoluble and non-specific. To target the acid environment of tumor sites, we synthesized three poly(ethylene glycol) methacrylate-co-2-(diisopropylamino)ethyl methacrylate (PEGMA-co-DPA) copolymers capable of self-assembly to form pH sensitive nanoparticles in an aqueous environment, as a means of encapsulating the water-insoluble photosensitizer, meso-tetra(hydroxyphenyl)chlorin (m-THPC). The critical aggregation pH of the PEGMA-co-DPA polymers was 5.8-6.6 and the critical aggregation concentration was 0.0045-0.0089 wt% at pH 7.4. Using solvent evaporation, m-THPC loaded nanoparticles were prepared with a high drug encapsulation efficiency (approximately 89%). Dynamic light scattering and transmission electron microscopy revealed the spherical shape and 132 nm diameter of the nanoparticles. The in vitro release rate of m-THPC at pH 5.0 was faster than at pH 7.0 (58% versus 10% m-THPC released within 48 h, respectively). The in vitro photodynamic therapy efficiency was tested with the HT-29 cell line. m-THPC loaded PEGMA-co-DPA nanoparticles exhibited obvious phototoxicity in HT-29 colon cancer cells after light irradiation. The results indicate that these pH sensitive nanoparticles are potential carriers for tumor targeting and photodynamic therapy.

The new ophthalmic formulation for infection control by combining collagen/gelatin/alginate biomaterial with liposomal chloramphenicol.

Eye drops are a conventional method of drug delivery to the eye, accounting for 90% of currently accessible ophthalmic formulations. The major problem with eye drop treatments is rapid pre-corneal drug loss. Furthermore, the need for frequent administration of eye drops can profoundly affect the quality of life of ophthalmological patients. In the current study, we developed a liposomal nanoparticle encapsulated with chloramphenicol mixed with biodegradable materials against ophthalmological disease. We first established a protocol for chloramphenicol (CAP) loaded into liposomal nanoparticle (LipoCAP). We also established the collagen/gelatin/sodium alginate (CGA) as the component of biodegradable polymers and calibrated the novel drug-releasing formulation. Finally, we combined LipoCAP with CGA to generate an 8-h degradable ophthalmic chloramphenicol gel, CGA-LipoCAP-8. CGA-LipoCAP-8 reached the effective working concentration in 75 min and prolonged the drug-releasing time for at least 12 h. In addition, CGA-LipoCAP-8 could stably and continuously inhibit E. coli proliferation. The inhibiting phenomenon was more pronounced over time. Furthermore, there were no significant toxicities observed when CGA-LipoCAP-8 co-cultured with ocular epithelial cells. In conclusion, CGA-LipoCAP-8 achieved effective CAP dose concentrations in a short time and sustained CAP release for a prolonged period. Our results provide an innovative concept in relation to novel drug-release formulations, with safety and efficiency supporting use in future treatments for ophthalmological diseases.

Indium-111-labeled CD166-targeted peptide as a potential nuclear imaging agent for detecting colorectal cancer stem-like cells in a xenograft mouse model.

BACKGROUND: Cancer stem cells (CSCs) are involved in drug resistance, metastasis, and relapse of cancers, which can significantly affect tumor therapy. Hence, to develop specifically therapeutic target probe at CSCs for improvement of survival and quality of life of cancer patients is urgently needed. The CD166 protein has been suggested to be involved in colorectal cancer (CRC) tumorigenesis and to be considered a marker for colorectal CSCs (CRCSCs) detection. In this study, therefore, we attend to apply a nuclear imaging agent probe, Glycine18-Cystine-linked CD166-targeted peptides (CD166tp-G18C), to detect the changes of CD166 level in a CRC xenograft mouse model. RESULTS: We isolated the CD166-positive cells from the HCT15 CRC cell line (CD166+HCT15) and evaluated their morphology and ability of clone formation, migration, protein expression, and drug resistance. The CD166-positive HCT15 cells display the CSCs characteristics. We discovered and designed a CD166-targeted peptide (CD166tp-G18C) as a targeted probe of CRC stem-like cell for cell binding assay. The CD166tp-G18C confirmed the CD166 protein targeting ability in CD166+HCT15 cells. The diethylenetriaminopentaacetic acid (DTPA)-conjugated CD166tp-G18C further was labeled with indium-111 (111In-DTPA-CD166tp-G18C) as nuclear imaging agent for imaging and bio-distribution analysis in vivo. Finally, we observed that the 111In-DTPA-CD166tp-G18C was significantly enhanced in tumor tissues of CD166+HCT15 xenograft mice as compared to the non-CD166tp-G18C control. CONCLUSIONS: Our results indicated that the indium-111-labeled CD166tp-G18C may be served as a powerful tool for colorectal CSCs nuclear imaging in the CRC patients.

Evaluating the potential of 188Re-SOCTA-trastuzumab as a new radioimmunoagent for breast cancer treatment.

INTRODUCTION: Radioimmunotherapy, which utilizes monoclonal antibodies and therapeutic radioisotopes against antigen-expressing tumor tissues, is an attractive therapeutic approach for cancer therapy. Trastuzumab (Herceptin) is a humanized anti-HER-2/neu monoclonal antibody for breast cancer treatment. In this paper, we introduce a new radioimmunoagent, (188)Re-trastuzumab, via a bifunctional ligand, succinimidyl 3,6-diaza-5-oxo-3-[2-((triphenylmethyl)thio)ethyl]-8-[(triphenylmethyl)thio]octanoate (SOCTA), and evaluate its potential to be a therapeutic radiopharmaceutical for breast cancer treatment. METHODS: Equimolar amounts of SOCTA and trastuzumab were selected to react, and the conjugation ratio of SOCTA-trastuzumab was evaluated by the MALDI-TOF method. The immunoreactivity of SOCTA-trastuzumab was compared with nonconjugated trastuzumab in HER-2/neu overexpressing human breast cancer cell BT-474. Biodistribution experiment and microSPECT/CT images of (188)Re-SOCTA-trastuzumab being administered intravenously to SCID mice bearing xenografted BT-474 breast cancer were investigated to evaluate the tumor-targeting capability. RESULTS: The covalent attachment of SOCTA to trastuzumab (at 1:1 molar ratio) resulted in the averaged conjugation ratio of 0.27+/-0.06 (n=3). The complex could easily be labeled with (188)Re and achieve 95% radiochemical purity (RCP) after 1 h of reaction at room temperature. The in vitro stability study also revealed that the RCP of (188)Re-SOCTA-trastuzumab was at a value of more than 85% after 48 h of incubation with human serum. The immunoreactivity evaluation showed that SOCTA-trastuzumab and nonconjugated trastuzumab had similar binding capacity (B(max)) to HER-2/neu receptor in BT-474 cells. The animal experiments showed that (188)Re-SOCTA-trastuzumab accumulated more intensively in the tumor site as compared to normal tissue. CONCLUSION: We suggest that (188)Re-SOCTA-trastuzumab could be a potential candidate for radioimmunotherapy.

Biodegradable and Multifunctional Microspheres for Treatment of Hepatoma through Transarterial Embolization.

To improve the effectiveness of cancer treatment, this study aimed to develop biodegradable microspheres and to combine chemotherapy and radiotherapy via transcatheter arterial embolization/chemoembolization (TAE/TACE) with local radiation therapy for the slow release of chemotherapeutic agents. Microparticles were prepared by double emulsification using a biodegradable and biocompatible polymer Poly(D,l-lactide-co-glycolide) (PLGA). Since the microspheres contain a water-soluble Poly(vinylsulfonic acid) (PVSA) solution, the functional groups of this polymer dissociate into -SO3- in water. The positively charged doxorubicin can be loaded into beads, ensuring slow release. After 188Retin colloids were added into the microspheres, TACE was performed in a rat hepatocellular carcinoma model. Single photon emission computed tomography/computed tomography imaging and biodistribution analyses showed that the microspheres were still in the liver after 72 h. During 4 weeks of observation, ultrasound images showed that the Re/DOX@MS treatment had the most significant inhibitory effect on tumor growth. Biodegradable PLGA microspheres have the advantage of enabling local embolization therapy with reduced adverse effects. In the future, microspheres could serve as a drug delivery system for cancer treatment by combining therapeutic radionuclides and chemotherapeutic drugs, thereby improving treatment effects for hepatocellular carcinoma.

Anti-angiogenic treatment (Bevacizumab) improves the responsiveness of photodynamic therapy in colorectal cancer.

Photodynamic therapy (PDT) is a treatment utilizing the combined action of photosensitizers and light for the treatment of various cancers. The mechanisms for tumor destruction after PDT include direct tumor cell kill by singlet oxygen species (OS), indirect cell kill via vascular damage, and an elicited immune response. However, it has been reported that many cellular activators, including vascular endothelial growth factor (VEGF), are produced by tumor cells after PDT. In this study, we demonstrate that meta-tetra(hydroxyphenyl) chlorin (mTHPC)-based photodynamic therapy combined with bevacizumab (Avastin™), an anti-VEGF neutralizing monoclonal antibody that blocks the binding of VEGF to its receptor, can enhance the effectiveness of each treatment modality. We evaluated the efficacy of bevacizumab-based anti-angiogenesis in combination with PDT as well as the resulting VEGF levels and microvessel density (MVD) in a mouse model of human colon cancer. Enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC) were performed to assess VEGF concentrations and microvessel density in the various treatment groups, and confocal imaging and high performance liquid chromatography (HPLC) analyses were used to measure the distribution and concentration of mTHPC in tumors. Our results demonstrate that combination of PDT followed by bevacizumab significantly elicits a greater tumor response whereas bevacizumab treatment prior to PDT led to a reduced tumor response. Immunostaining and ELISA analyses revealed a lower expression of VEGF in tumors treated with combination therapy of PDT followed by bevacizumab. However, bevacizumab treatment decreased the accumulation of mTHPC in tumors 24 h after administration, which complemented the results of decreased anti-tumor efficacy of bevacizumab followed by PDT.

Biodistribution, pharmacokinetics and imaging of (188)Re-BMEDA-labeled pegylated liposomes after intraperitoneal injection in a C26 colon carcinoma ascites mouse model.

Nanoliposomes are important carriers capable of packaging drugs for various delivery applications through passive targeting tumor sites by enhanced permeability and retention effect. Radiolabeled liposomes have potential applications in radiotherapy and diagnostic imaging. The purpose of this study was to investigate the biodistribution, pharmacokinetics and imaging of nanotargeted (188)Re-N,N-bis (2-mercaptoethyl)-N',N'-diethylethylenediamine (BMEDA)-labeled pegylated liposomes (RBLPL) and unencapsulated (188)Re-BMEDA after intraperitoneal (ip) injection in a C26 colon carcinoma ascites mouse model. The nanopegylated liposomes were labeled with (188)Re-BMEDA. The labeling efficiency of RBLPL was 82.3+/-4.5%. In vitro stability of RBLPL in normal saline at room temperature and in rat plasma at 37 degrees C for 72 h was 92.01+/-1.31% and 82.4+/-1.64%, respectively. The biodistribution studies indicated that the radioactivity in ascites was 69.96+/-14.08 percentage injected dose per gram (% ID/g) at 1h to 5.99+/-1.97% ID/g at 48 h after ip administration of RBLPL. The levels of radioactivity in tumor were progressive accumulation to a maximum of 6.57+/-1.7% ID/g at 24 h. The radioactivity of (188)Re-BMEDA in ascites reached the maximum level of 54.89+/-5.91% ID/g at 1 h and declined rapidly with time. Pharmacokinetic studies revealed that the terminal half-life, total body clearance and area under the curve of RBLPL were 5.3-, 9.5- and 9.4-fold higher than that of (188)Re-BMEDA in blood, respectively. These results suggested that the long circulation, bioavailability and localization of RBLPL in tumor and ascites sites, which also demonstrate that the ip administration of RBLPL is a potential multifunctional nanoradiotherapeutics and imaging agents on a C26 colon carcinoma ascites mouse model.

Biodistribution, pharmacokinetics and microSPECT/CT imaging of 188Re-bMEDA-liposome in a C26 murine colon carcinoma solid tumor animal model.

Nanoliposomes are useful carriers in drug delivery. Radiolabeled nanoliposomes have potential applications in radiotherapy and diagnostic imaging. In this study, the biodistribution and pharmacokinetics of 188Re-BMEDA-labelled pegylated liposomes (RBLPL) and unencapsulated 188Re-BMEDA administered by the i.v. route in murine C26-colon tumour-bearing mice were investigated. MicroSPECT/CT images were performed to evaluate the distribution and tumor targeting of RBLPL in mice. For the biodistribution study, the highest uptake of liposome in tumors was 3.62% +/- 0.73% at 24 h after RBLPL administration, and the tumor to muscle ratio of RBLPL was 7.1-fold higher than that of 188Re-BMEDA. With image analysis, the highest SUV in tumor was 2.81 +/- 0.26 at 24 h after injection of RBLPL. The Pearson correlation analysis showed a positive correlation of tumor targeting or uptake of RBLPL between biodistribution and microSPECT semi-quantification imaging analysis (r = 0.633). The results of the pharmacokinetics revealed that the area under the tissue concentration-time curve (AUC) of RBLPL was 4.7-fold higher than that of unencapsulated 188Re-BMEDA. These results suggested the potential benefit and advantage of 188Re-labeled nanoliposomes for imaging and treatment of malignant diseases.

Reducing renal uptake of 111In-DOTATOC: a comparison among various basic amino acids.

PURPOSE: Several studies have reported significant renal toxicity after the use of a high dose of 90Y-DOTATOC. Thus, renal protection is necessary in treatments with 90Y-DOTA Tyr3-octreotide (DOTATOC). The infusion of certain positively charged amino acids has been shown to effectively reduce renal uptake of DOTATOC. In this study, we compared the effectiveness of three kinds of amino acids, D-lysine (lysine), L-arginine (arginine) and histidine, on renal protection in healthy rats and tried to determine which one was the most effective. METHODS: Twenty SD healthy male rats were divided into 4 groups: lysine, histidine, arginine, and control. The rats were injected with a dose of 400 mg/kg of amino acid or 2 ml of phosphate-buffered saline (PBS) (as control) intraperitoneally. All rats were sacrificed at 4 hrs after the injection of 1 MBq 111In-DOTATOC. Samples of the kidney were taken and weighed carefully. The counts of radioactivity were measured by a gamma counter and renal concentrations were calculated and expressed as percent injected dose per gram (% ID/g). RESULTS: The renal uptake of 111In-DOTATOC was significantly lower for all three kinds of amino acids when compared to the control group. The renal uptake of 111In-DOTATOC in the lysine group was significantly lower than those in the histidine and arginine groups. The renal uptake of 111In-DOTATOC in the histidine group was lower than that in the arginine group, but no statistical difference was noted. CONCLUSION: Among these three amino acids, lysine had the best reduction rate of renal uptake of DOTATOC. Histidine was more effective than arginine but no statistical difference was noted.

A design for automatic preparation of highly concentrated 188Re-perrhenate solutions.

Rhenium-188 is extremely suitable for the radiotherapy of balloon dilation for the coronary artery restenosis. To satisfy the need of highly concentrated (188)Re-perrhenate for the clinical applications, we designed an apparatus to achieve the purpose of concentrating (188)Re-perrhenate solution. This apparatus comprised of a concentrator, a control box and a computer with an automatic control program. A column of cation-exchange resin in Ag(+) form and an anion-exchange column in series were used in the concentration procedure. More than 90% of (188)Re isotope in the original solution could be collected with 1mL of 0.9% NaCl solution added to collect the (188)Re adsorbed in the column in this final process (90.7+/-2.2%, n=15). We also found that the radiochemical purity in the final solution remained unchanged (100%). The designed process could automatically increase the quality and efficiency of the production of highly concentrated rhenium-188 solution, and could also reduce the radiation dose absorbed by the operator.

EGFR-targeted micelles containing near-infrared dye for enhanced photothermal therapy in colorectal cancer.

The purpose of this research was to investigate the effectiveness of epidermal growth factor receptor (EGFR) targeted micelles loaded with IR-780 (Cetuximab/IR-780/micelles) for generating tumor targeting, multimodal images, and photothermal therapy (PTT). We initially studied the cellular uptake of these micelles using the HCT-116 and SW-620 cell lines. HCT-116 (high expression of EGFR) and SW-620 (low expression of EGFR) cell lines were used to examine biodistribution and antitumor effects of Cetuximab/IR-780/micelles. Time-lapse near-IR fluorescence (NIRF) images also indicated the highest IR-780 accumulation from Cetuximab/IR-780/micelles in HCT-116 tumors (p<0.05). HCT-116 tumors in tumor-bearing mice exhibited significantly higher accumulations of Cetuximab/IR-780/111In-micelles than SW-620 tumors in Micro-SPECT/CT imaging and biodistribution studies (p<0.05). Dual-radioisotope Nano-SPECT/CT imaging of Cetuximab/131I-IR-780/111In-micelles demonstrated simultaneous high accumulation of both IR-780 and micelles in HCT-116 tumors, but not in SW-620 tumors. Regarding antitumor effects, following the Cetuximab/IR-780/micelles with PPT on day 6, all HCT-116 tumor-bearing mice were cured. In contrast, SW-620 tumors relapsed at 13days after treatment. In summary, we expect that the Cetuximab/IR-780/micelles could enhance the antitumor effects by PTT in EGFR overexpression colorectal cancers through effective drug delivery nanoparticles.