Translating Research for the Radiotheranostics of Nanotargeted 188Re-Liposome.

Nanoliposomes are one of the leading potential nano drug delivery systems capable of targeting chemotherapeutics to tumor sites because of their passive nano-targeting capability through the enhanced permeability and retention (EPR) effect for cancer patients. Recent advances in nano-delivery systems have inspired the development of a wide range of nanotargeted materials and strategies for applications in preclinical and clinical usage in the cancer field. Nanotargeted 188Re-liposome is a unique internal passive radiotheranostic agent for nuclear imaging and radiotherapeutic applications in various types of cancer. This article reviews and summarizes our multi-institute, multidiscipline, and multi-functional studied results and achievements in the research and development of nanotargeted 188Re-liposome from preclinical cells and animal models to translational clinical investigations, including radionuclide nanoliposome formulation, targeted nuclear imaging, biodistribution, pharmacokinetics, radiation dosimetry, radiation tumor killing effects in animal models, nanotargeted radionuclide and radio/chemo-combination therapeutic effects, and acute toxicity in various tumor animal models. The systemic preclinical and clinical studied results suggest 188Re-liposome is feasible and promising for in vivo passive nanotargeted radionuclide theranostics in future cancer care applications.

Bi-Functional Radiotheranostics of 188Re-Liposome-Fcy-hEGF for Radio- and Chemo-Therapy of EGFR-Overexpressing Cancer Cells.

Epidermal growth factor receptor (EGFR) specific therapeutics is of great importance in cancer treatment. Fcy-hEGF fusion protein, composed of yeast cytosine deaminase (Fcy) and human EGF (hEGF), is capable of binding to EGFR and enzymatically convert 5-fluorocytosine (5-FC) to 1000-fold toxic 5-fluorocuracil (5-FU), thereby inhibiting the growth of EGFR-expressing tumor cells. To develop EGFR-specific therapy, 188Re-liposome-Fcy-hEGF was constructed by insertion of Fcy-hEGF fusion protein onto the surface of liposomes encapsulating of 188Re. Western blotting, MALDI-TOF, column size exclusion and flow cytometry were used to confirm the conjugation and bio-activity of 188Re-liposome-Fcy-hEGF. Cell lines with EGFR expression were subjected to treat with 188Re-liposome-Fcy-hEGF/5-FC in the presence of 5-FC. The 188Re-liposome-Fcy-hEGF/5-FC revealed a better cytotoxic effect for cancer cells than the treatment of liposome-Fcy-hEGF/5-FC or 188Re-liposome-Fcy-hEGF alone. The therapeutics has radio- and chemo-toxicity simultaneously and specifically target to EGFR-expression tumor cells, thereby achieving synergistic anticancer activity.

Evaluation of Nanotargeted 111In-Cyclic RGDfK-Liposome in a Human Melanoma Xenotransplantation Model.

Nanotargeted liposomes may be modified with targeting peptide on the surface of a prepared liposome to endow specificity and elevate targeting efficiency. The aim of this study was to develop a radioactive targeted nanoparticle, the 111In-cyclic RGDfK-liposome, and its advantage of recognizing the αVß3 integrin was examined. The cyclic RGDfK modified liposomes were demonstrated the ability to bind the αVß3 integrin expressed on the surface of human melanoma cell in vitro and in vivo. The effects of the cyclic RGDfK-liposome on the functioning of phagocytes was also examined, showing no considerable negative effects on the engulfment of bacteria and the generation of reactive oxygen species. Based upon these findings, the cyclic RGDfK- liposome is said to be a promising agent for tumor imaging.

A phase 0 study of the pharmacokinetics, biodistribution, and dosimetry of 188Re-liposome in patients with metastatic tumors.

BACKGROUND: Liposomes are drug nano-carriers that are capable of targeting therapeutics to tumor sites because of enhanced permeability retention (EPR). In several preclinical studies with various tumor-bearing mice models, 188Re-liposome that has been developed by the Institute of Nuclear Energy Research (INER) demonstrates favorable in vivo tumor targeting, biodistribution, pharmacokinetics, and dosimetry. It inhibits the growth of tumors, increased survival, demonstrates good synergistic combination, and was safe to use. This study conducts a phase 0 low-radioactivity clinical trial of nano-targeted radiotherapeutics 188Re-liposome to evaluate the effectiveness with which it targets tumors and the pharmacokinetics, biodistribution, dosimetry, and its safety in use. Twelve patients with metastatic cancers are studied in this trial. Serial whole-body scans and SPECT/CT are taken at 1, 4, 8, 24, 48, and 72 h after intravenous injection of 111 MBq of 188Re-liposome. The effectiveness with which tumors are targeted, the pharmacokinetics, biodistribution, dosimetry, and safety are evaluated using the VelocityAI and OLINDA/EXM software. Blood samples are collected at different time points for a pharmacokinetics study and a safety evaluation that involves monitoring changes in liver, renal, and hematological functions. RESULTS: The T½z for 188Re-liposome in blood and plasma are 36.73 ± 14.00 h and 52.02 ± 45.21 h, respectively. The doses of radiation that are absorbed to vital organs such as the liver, spleen, lung, kidney, and bone marrow are 0.92 ± 0.35, 1.38 ± 1.81, 0.58 ± 0.28, 0.32 ± 0.09, and 0.06 ± 0.01 mGy/MBq, respectively, which is far less than the reference maximum tolerance dose after injection of 188Re-liposome. 188Re-liposome is absorbed by metastatic tumor lesions and the normal reticuloendothelial (RES) system. Certain patients exhibit a therapeutic response. CONCLUSION: This phase 0 exploratory IND study shows that nanocarrier 188Re-liposome achieves favorable tumor accumulation and tumor to normal organ uptake ratios for a subset of cancer patients. The clinical pharmacokinetic, biodistribution, and dosimetry results justify a further dose-escalating phase 1 clinical trial. TRIAL REGISTRATION: Taiwan FDA MA1101G0 (Jan 31, 2012).

PEGylated liposome-encapsulated rhenium-188 radiopharmaceutical inhibits proliferation and epithelial-mesenchymal transition of human head and neck cancer cells in vivo with repeated therapy.

Human head and neck squamous cell carcinoma (HNSCC) is usually treated with chemoradiotherapy, but the therapeutic efficacy could be hampered by intrinsic radioresistance and early relapse. Repeated administrations of rhenium-188 (188Re)-conjugated radiopharmaceutical has been reported to escalate the radiation doses for better control of advanced human cancers. Here we found that high dosage of 188Re-liposome, the liposome-encapsulated 188Re nanoparticles exhibited significant killing effects on HNSCC FaDu cells and SAS cells but not on OECM-1 cells. To investigate the biological and pharmaceutical responses of high 188Re-liposomal dosage in vivo, repeated doses of 188Re-liposome was injected into the orthotopic tumor model. FaDu cells harboring luciferase reporter genes were implanted in the buccal positions of nude mice followed by intravenous injection of 188Re-liposome. The Cerenkov luminescence imaging (CLI) was performed to demonstrate an increased accumulation of 188Re-liposome in the tumor lesion of nude mice with repeated doses compared to a single dose. Repeated doses also enhanced tumor growth delay and elongated the survival of tumor-bearing mice. These observations were associated with significant loss of Ki-67 proliferative marker and epithelial-mesenchymal transition (EMT) markers in excised tumor cells. The body weights of mice were not significantly changed using different doses of 188Re-liposome, yet repeated doses led to lower blood counts than a single dose. Furthermore, the pharmacokinetic analysis showed that the internal circulation of repeated 188Re-liposomal therapy was elongated. The biodistribution analysis also demonstrated that accumulations of 188Re-liposome in tumor lesions and bone marrow were increased using repeated doses. The absorbed dose of repeated doses over a single dose was about twofold estimated for a 1 g tumor. Together, these data suggest that the radiopharmacotherapy of 188Re-liposome can enhance tumor suppression, survival extension, and internal circulation without acute toxicity using repeated administrations.

188Re-Liposome Can Induce Mitochondrial Autophagy and Reverse Drug Resistance for Ovarian Cancer: From Bench Evidence to Preliminary Clinical Proof-of-Concept.

Despite standard treatment, about 70% of ovarian cancer will recur. Cancer stem cells (CSCs) have been implicated in the drug-resistance mechanism. Several drug resistance mechanisms have been proposed, and among these, autophagy plays a crucial role for the maintenance and tumorigenicity of CSCs. Compared to their differentiated counterparts, CSCs have been demonstrated to display a significantly higher level of autophagy flux. Moreover, mitophagy, a specific type of autophagy that selectively degrades excessive or damaged mitochondria, is shown to contribute to cancer progression and recurrence in several types of tumors. Nanomedicine has been shown to tackle the CSCs problem by overcoming drug resistance. In this work, we developed a nanomedicine, 188Re-liposome, which was demonstrated to target autophagy and mitophagy in the tumor microenvironment. Of note, the inhibition of autophagy and mitophagy could lead to significant tumor inhibition in two xenograft animal models. Lastly, we presented two cases of recurrent ovarian cancer, both in drug resistance status that received a level I dose from a phase I clinical trial. Both cases developing drug resistance showed drug sensitivity to 188Re-liposome. These results suggest that inhibition of autophagy and mitophagy by a nanomedicine may be a novel strategy to overcome drug resistance in ovarian cancer.

Imaging, biodistribution and efficacy evaluation of 188Re-human serum albumin microspheres via intraarterial route in an orthotopic hepatoma model.

PURPOSE: Liver cancer is the second most common cause of death worldwide. This study was to investigate the SPECT/CT, ultrasound, biodistribution and therapeutic evaluation of 188Re-human serum albumin microspheres (188Re-HSAM) in the GP7TB orthotopic hepatoma rat model. MATERIALS AND METHODS: HSAM was labeled with 188Re by using a home-made kit and microwave system. The 188Re-HSAM was administered via intraarterial route. The in vivo distribution of 188Re-HSAM was determined by biodistribution analysis and nanoSPECT/CT system. In efficacy, tumor volumes were tracked longitudinally by three-dimensional ultrasound. RESULTS: The biodistribution and nanoSPECT/CT imaging showed that 188Re-HSAM could accumulate in liver and tumor. The correlation coefficient of tumor volumes done by three-dimensional ultrasound and at autopsy was 0.997. In efficacy, tumor volume in the normal saline-treated group was 1803.2 mm3 at 54 days after tumor inoculation. Tumor volumes in the 103.6 MBq and 240.5 MBq of 188Re-HSAM treated groups were 381 and 267.4 mm3 (p = 0.001 and 0.004), respectively. CONCLUSIONS: These results show that three-dimensional ultrasound with a high spatial resolution and contrast in soft tissue can become imaging modality in assessing tumor burden and tumor progression in an orthotopic rat model. The longitudinally therapeutic evaluation of 188Re-HSAM demonstrated dose-dependent tumor growth inhibition with increased dose in the GP7TB orthotopic hepatoma rat model.

Involvement of let-7 microRNA for the therapeutic effects of Rhenium-188-embedded liposomal nanoparticles on orthotopic human head and neck cancer model.

Human head and neck squamous cell carcinoma (HNSCC) is usually treated by surgical resection with adjuvant radio-chemotherapy. In this study, we examined whether the radiopharmaceutical 188Re-liposome could suppress the growth of HNSCC followed by an investigation of molecular mechanisms. The orthotopic HNSCC tumor model was established by human hypopharyngeal FaDu carcinoma cells harboring multiple reporter genes. The drug targeting and therapeutic efficacy of 188Re-liposome were examined using in vivo imaging, bio-distribution, pharmacokinetics, and dosimetry. The results showed that 188Re-liposome significantly accumulated in the tumor lesion compared to free 188Re. The circulation time and tumor targeting of 188Re-liposome were also longer than that of free 188Re in tumor-bearing mice. The tumor growth was suppressed by 188Re-liposome up to three weeks using a single dose treatment. Subsequently, microarray analysis followed by Ingenuity Pathway Analysis (IPA) showed that tumor suppressor let-7 microRNA could be an upstream regulator induced by 188Re-liposome to regulate downstream genes. Additionally, inhibition of let-7i could reduce the effects of 188Re-liposome on suppression of tumor growth, suggesting that let-7 family was involved in 188Re-liposome mediated suppression of tumor growth in vivo. Our data suggest that 188Re-liposome could be a novel strategy for targeting HNSCC partially via induction of let-7 microRNA.

Structure-based optimization of GRP78-binding peptides that enhances efficacy in cancer imaging and therapy.

It is more challenging to design peptide drugs than small molecules through molecular docking and in silico analysis. Here, we developed a structure-based approach with various computational and analytical techniques to optimize cancer-targeting peptides for molecular imaging and therapy. We first utilized a peptide-binding protein database to identify GRP78, a specific cancer cell-surface marker, as a target protein for the lead, L-peptide. Subsequently, we used homologous modeling and molecular docking to identify a peptide-binding domain within GRP78 and optimized a series of peptides with a new protein-ligand scoring program, HotLig. Binding of these peptides to GRP78 was confirmed using an oriented immobilization technique for the Biacore system. We further examined the ability of the peptides to target cancer cells through in vitro binding studies with cell lines and clinical cancer specimens, and in vivo tumor imaging and targeted chemotherapeutic studies. MicroSPECT/CT imaging revealed significantly greater uptake of (188)Re-liposomes linked to these peptides as compared with non-targeting (188)Re-liposomes. Conjugation with these peptides also significantly increased the therapeutic efficacy of Lipo-Dox. Notably, peptide-conjugated Lipo-Dox significantly reduced stem-cell subpopulation in xenografts of breast cancer. The structure-based optimization strategy for peptides described here may be useful for developing peptide drugs for cancer imaging and therapy.

Intraperitoneal (188)Re-Liposome delivery switches ovarian cancer metabolism from glycolysis to oxidative phosphorylation and effectively controls ovarian tumour growth in mice.

BACKGROUND AND PURPOSE: Cancer stem cells exhibit distinctive cellular metabolism compared with the more differentiated counterparts or normal cells. We aimed to investigate the impact of a novel radionuclide anti-cancer agent (188)Re-Liposome on stemness markers' expression and cellular metabolism in an ovarian cancer model. MATERIAL AND METHODS: A 2×2 factorial experiment was designed in which factor 1 represented the drug treatment comparing (188)Re-BMEDA, a free form of (188)Re, with (188)Re-Liposome, a nanoparticle-encapsulated form of (188)Re. Factor 2 represented the delivery route, comparing intravenous with intraperitoneal delivery. RESULTS: Intraperitoneal delivery of (188)Re-Liposome predominantly killed the CSCs-like cells in tumours and switched metabolism from glycolysis to oxidative phosphorylation. Further, intraperitoneal delivery of (188)Re-Liposome treatment was able to block epithelial-to-mesenchymal transition (EMT) and reactivate p53 function. Collectively, these molecular changes led to a striking tumour-killing effect. CONCLUSIONS: Radionuclides encapsulated in liposomes may represent a novel treatment for ovarian cancer when delivered intraperitoneally (a type of loco-regional delivery). In the future, this concept may be further extended for the treatment of several relevant cancers that have been proved to be suitable for loco-regional delivery of therapeutic agents, such as colon cancer, gastric cancer, and pancreatic cancer.

Cytotoxic Effects of PEGylated Anti-EGFR Immunoliposomes Combined with Doxorubicin and Rhenium-188 Against Cancer Cells.

BACKGROUND/AIM: We aimed to construct epidermal growth factor receptor (EGFR)-targeting cetuximab-immunoliposomes (IL-C225) for targeted delivery of doxorubicin and rhenium-188 (Re-188) to EGFR(+) cancer cells. MATERIALS AND METHODS: Synthesized IL-C225 was analyzed by dynamic light scattering, transmission electron microscopy, and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. Cell binding and internalization were examined using doxorubicin-loaded IL-C225 (DXR-IL-C225) with confocal microscopy. IL-C225 combined with doxorubicin and Re-188 ((188)Re-DXR-IL-C225) was synthesized, and the cytotoxic effects of (188)Re-DXR-IL-C225 were analyzed in EGFR(+) cancer cells using cell viability assays. RESULTS: IL-C225 bound to EGFR on A431 cancer cells and was rapidly internalized. Furthermore, IL-C225 localized within the tumor cells efficiently. (188)Re-DXR-IL-C225 exhibited outstanding cytotoxic effects against EGFR(+) cancer cells in vitro and showed superior cytotoxic effects compared to DXR-IL-C225 or (188)Re-IL-C225 alone. CONCLUSION: The new formulation of (188)Re-DXR-IL-C225 may be a potential theranostic vehicle for delivery of drugs in the treatment of EGFR-overexpressing human cancer.

Characteristic Comparison Between 131I-Interferon-α and 131I-Interferon-α-Immunoglobulin-Fc Hybrid Protein in Rats Using Molecular Imaging.

BACKGROUND/AIM: Interferon-α (IFN-α) is produced to act locally and transiently with a relatively short circulation half-life in vivo. Hybridization of IFN-α with human immunoglobulin Fc, renamed as IFN-α-Fc, may overcome this limitation. In the present study, (131)I-IFN-α-Fc and (131)I-IFN-α were compared in the aspects of stability, pharmacokinetics, tissue distribution and molecular imaging quality in an animal model. MATERIALS AND METHODS: Both IFN-α-Fc and IFN-α were labelled with (131)I. Biodistributions and pharmacokinetics of both labelled proteins in Sprague-Dawley rats were assayed. Micro-single-photon emission computed tomography/computed tomography was used to non-invasively monitor the longitudinal distribution of both proteins. RESULTS: (131)I-IFN-α-Fc was shown to have higher stability than (131)I-IFN-α in whole blood, plasma, kidney, liver and stomach from the biodistribution study. The area under curve analyzed from plasma in the phomacokinetics study was 10-fold higher for (131)I-IFN-α-Fc than for (131)I-IFN-α. At 0-1 h post tail-vein injection, both labelled proteins are mainly accumulated in the kidneys and liver. Notably, (131)I-IFN-α-Fc is degraded more slowly than (131)I-IFN-α. CONCLUSION: We demonstrated that (131)I-IFN-α-Fc has longer blood circulation time and better biostability than (131)I-IFN-α, suggesting the potential application of the immunoglobulin Fc-conjugated cytokine for long-term treatment of diseases.

External beam radiotherapy synergizes ¹88Re-liposome against human esophageal cancer xenograft and modulates ¹88Re-liposome pharmacokinetics.

External beam radiotherapy (EBRT) treats gross tumors and local microscopic diseases. Radionuclide therapy by radioisotopes can eradicate tumors systemically. Rhenium 188 ((188)Re)-liposome, a nanoparticle undergoing clinical trials, emits gamma rays for imaging validation and beta rays for therapy, with biodistribution profiles preferential to tumors. We designed a combinatory treatment and examined its effects on human esophageal cancer xenografts, a malignancy with potential treatment resistance and poor prognosis. Human esophageal cancer cell lines BE-3 (adenocarcinoma) and CE81T/VGH (squamous cell carcinoma) were implanted and compared. The radiochemical purity of (188)Re-liposome exceeded 95%. Molecular imaging by NanoSPECT/CT showed that BE-3, but not CE81T/VGH, xenografts could uptake the (188)Re-liposome. The combination of EBRT and (188)Re-liposome inhibited tumor regrowth greater than each treatment alone, as the tumor growth inhibition rate was 30% with EBRT, 25% with (188)Re-liposome, and 53% with the combination treatment at 21 days postinjection. Combinatory treatment had no additive adverse effects and significant biological toxicities on white blood cell counts, body weight, or liver and renal functions. EBRT significantly enhanced the excretion of (188)Re-liposome into feces and urine. In conclusion, the combination of EBRT with (188)Re-liposome might be a potential treatment modality for esophageal cancer.

Preparation and imaging of rhenium-188 labeled human serum albumin microsphere in orthotopic hepatoma rats.

OBJECTIVE: The present study relates to a method for preparing 188Re-labeled human serum albumin microspheres (HSAM) by 188Re(I)-tricarbonyl ion(188Re(OH2)3(CO)3)+). This radioactive particle can be subjected to radioembolization for liver tumor. METHODS: The particle sizes and conformations of HSA microspheres were analyzed by Particle sizes-Malvern mastersizer and Scanning Electron Microscope (SEM). For preparing 188Re(I)-tricarbonyl ion, the 188ReO4- was eluted from a 188W/188Re generator with saline. The radio labeling efficiency was analyzed with high-performance liquid chromatography (HPLC). Amino borane-reduced 188ReO4-was interacted with carbon oxide to form (188Re(OH2)3(CO)3]+). For preparing 188Re-HSA microspheres, the 188Re(I)-tricarbonyl ion was added into a vial with HSA microspheres. The in vitro stability was investigated. The rat was injected with 188Re-HSA microspheres via hepatic artery route. Nano-SPECT/CT Imaging was acquired after injection of 188Re-HSA microspheres. RESULTS: The shape of HSA microsphere was rough surfaced sphere or oval-shaped. The particle size was distributed between 20 and 35µm. In the RP-HPLC-UV chromatography, the yield of 188Re(I)-tricarbonyl ion was 75-80%. The labeling efficiency of 188Re-HSA microspheres in this method was more than 85%. After incubation, the 188Re(I)-tricarbonyl ion labeled HSA microspheres were found to be stable in vitro in normal saline and rat plasma. The result of Nano-SPECT/CT Imaging quantification analysis indicated that the percentage of injection dose %ID was maintained at 95% ID-88% ID from 2 to 72h after injection with 188Re- HSA microspheres. CONCLUSIONS: The method of 188Re(I)-tricarbonyl ion labeled HSA microspheres can proceed with high labeling yield. Furthermore, this method provided a convenient method for radio-labeling of HSA microspheres with 188Re as well as a kit for manufacturing.

Evaluation of 188Re-labeled PEGylated nanoliposome as a radionuclide therapeutic agent in an orthotopic glioma-bearing rat model.

PURPOSE: In this study, the (188)Re-labeled PEGylated nanoliposome ((188)Re-liposome) was prepared and evaluated as a therapeutic agent for glioma. MATERIALS AND METHODS: The reporter cell line, F98(luc) was prepared via Lentivector expression kit system and used to set up the orthotopic glioma-bearing rat model for non-invasive bioluminescent imaging. The maximum tolerated dose applicable in Fischer344 rats was explored via body weight monitoring of the rats after single intravenous injection of (188)Re-liposome with varying dosages before the treatment study. The OLINDA/EXM 1.1 software was utilized for estimating the radiation dosimetry. To assess the therapeutic efficacy, tumor-bearing rats were intravenously administered (188)Re-liposome or normal saline followed by monitoring of the tumor growth and animal survival time. In addition, the histopathological examinations of tumors were conducted on the (188)Re-liposome-treated rats. RESULTS: By using bioluminescent imaging, the well-established reporter cell line (F98(luc)) showed a high relationship between cell number and its bioluminescent intensity (R(2)=0.99) in vitro; furthermore, it could also provide clear tumor imaging for monitoring tumor growth in vivo. The maximum tolerated dose of (188)Re-liposome in Fischer344 rats was estimated to be 333 MBq. According to the dosimetry results, higher equivalent doses were observed in spleen and kidneys while very less were in normal brain, red marrow, and thyroid. For therapeutic efficacy study, the progression of tumor growth in terms of tumor volume and/or tumor weight was significantly slower for the (188)Re-liposome-treated group than the control group (P<0.05). As a result, the lifespan of glioma-bearing rats treated with (188)Re-liposome was prolonged 10.67% compared to the control group. CONCLUSION: The radiotherapeutic evaluation by dosimetry and survival studies have demonstrated that passive targeting (188)Re-liposome via systemic administration can significantly prolong the lifespan of orthotopic glioma-bearing rats while maintaining reasonable systemic radiation safety. Therefore, (188)Re-liposome could be a potential therapeutic agent for glioblastoma multiforme treatment.

Evaluation of the therapeutic and diagnostic effects of PEGylated liposome-embedded 188Re on human non-small cell lung cancer using an orthotopic small-animal model.

UNLABELLED: Non-small cell lung cancer (NSCLC) is a highly morbid and mortal cancer type that is difficult to eradicate using conventional chemotherapy and radiotherapy. Little is known about whether radionuclide-based pharmaceuticals can be used for treating NSCLC. Here we embedded the therapeutic radionuclide (188)Re in PEGylated (PEG is polyethylene glycol) liposomes and investigated the biodistribution, pharmacokinetics, and therapeutic efficacy of this nanoradiopharmaceutical on NSCLC using a xenograft lung tumor model and the reporter gene imaging techniques. METHODS: Human NSCLC NCI-H292 cells expressing multiple reporter genes were used in this study. (188)Re was conjugated to N,N-bis(2-mercaptoethyl)-N',N'-diethylethylenediamine (BMEDA) and loaded into the PEGylated liposome to form a (188)Re-liposome. The tumor growth rates and localizations were confirmed using bioluminescent imaging and SPECT/CT after the (188)Re-BMEDA or (188)Re-liposome was intravenously injected. The accumulation of the nanodrug in various organs was determined by the biodistribution analysis and the nano-SPECT/CT system. The pharmacokinetic and dosimetric analyses were further determined using WinNonlin and OLINDA/EXM, respectively. RESULTS: The biodistribution and nano-SPECT/CT imaging showed that PEGylated (188)Re-liposome could efficiently accumulate in xenograft tumors formed by NCI-H292 cells that were subcutaneously implanted in nude mice. Pharmacokinetic analysis also showed that the retention of (188)Re-liposome was longer than that of (188)Re-BMEDA. In an orthotopic tumor model, ex vivo γ counting revealed that the uptake of (188)Re-liposome was detected in tumor lesions but not in surrounding normal lung tissues. Moreover, we evaluated the therapeutic efficacy using bioluminescent imaging and showed that the lung tumor growth was suppressed but not eradicated by (188)Re-liposome. The life span of (188)Re-liposome-treated mice was 2-fold longer than that of untreated control mice. CONCLUSION: The results of biodistribution, pharmacokinetics, estimated dosimetry, nano-SPECT/CT, and bioluminescent imaging suggest that the PEGylated liposome-embedded (188)Re could be used for the treatment of human lung cancers.

The PEGylated liposomal doxorubicin improves the delivery and therapeutic efficiency of 188Re-Liposome by modulating phagocytosis in C26 murine colon carcinoma tumor model.

Liposome in delivering radionuclide for cancer therapy has been expansively studied; however, liposome itself can be deliberately entrapped and destroyed by the reticuloendothelial system, causing an insufficiency of the drug delivery, which in turn would restrict the effectiveness of the drug. In this study, mice with subcutaneous implantation of C26 murine colon cancer received an experimental treatment regimen in which mice took delivery of PEGylated liposomal doxorubicin (LipoDox) first, after a three-day interval, of Rhenium-188 encapsulated into PEGylated liposome ((188)Re-Liposome) subsequently and by which suppressed the functioning of reticuloendothelial system for the short term. The data showed that based upon the biodistribution assay and the evaluation of the therapeutic efficacy, (188)Re-Liposome was more sufficiently delivered to tumor sites in mice with this treatment regimen than mice without the regimen, and that cancer mortalities in mice with the treatment regimen were much lower than the mortalities in mice without the regimen. Taken together, a new strategy proposed in this study significantly improved both the (188)Re-Liposome delivery and the effectiveness of (188)Re-Liposome, suggesting that the strategy can be an ideal treatment for cancer.

Radioprotective effects of Antrodia cinnamomea are enhanced on immune cells and inhibited on cancer cells.

UNLABELLED: Abstract Purpose: The radioprotective effects of Antrodia cinnamomea (AC) were investigated for understanding the potential usefulness of AC as an adjunct treatment for reducing radiation side-effects. MATERIALS AND METHODS: In this study, we determined the ability of AC extracts (AC539) to reduce radiation side-effects by analyzing cellular viability in normal mouse spleen immune cells and human cancer cells with different radiosensitivity. We further detected the effect of AC on radiation-induced changes in cytokine- and inflammatory-related gene expressions. Furthermore, apoptosis assay was performed to determine whether AC could inhibit radiation-induced cytotoxicity. RESULTS: We found that an AC dose of 100-150 µg/ml in a time-dependent manner was the most effective in blocking radiation-induced cytotoxicity, in vitro. Radiation-induced cytotoxicity was inhibited in spleen immune cells by 37-56%; however, pretreatment of human colorectal cancer cell line HT-29 with AC did not have any effect on radiation-induced cytotoxicity, while pretreatment of radiosensitive human breast cancer cell lines BT-474 with AC caused a moderate enhancement of radiation-induced damage. Furthermore, AC pretreatment differentially regulated the mRNA expression of several important immunomodulatory genes in response to irradiation in normal and cancer cells. CONCLUSIONS: Our data indicate that AC may inhibit important immunoregulatory signaling which could be vital in the avoidance of an over-activated cytotoxic and inflammatory response of the immune system caused by radiation-induced tissue damage. Additionally, AC does not provide a radioprotective effect to tumor cells but instead enhances radiation-induced inflammation and cytotoxicity in cancer.

Combined therapeutic efficacy of 188Re-liposomes and sorafenib in an experimental colorectal cancer liver metastasis model by intrasplenic injection of C26-luc murine colon cancer cells.

Rhenium-188 (188Re) displays abundant intermediate energy ß emission and possesses a physical half-life of 16.9 h. Sorafenib is an orally available multikinase inhibitor that targets Raf kinases and vascular endothelial growth factor receptors (VEGFRs). Sorafenib has demonstrated preclinical and clinical activity against several types of tumors, such as renal cell and colorectal carcinoma. In this study, we investigated the efficacy of radiotherapeutics of 188Re-liposomes combined with sorafenib in a C26-luc metastatic colorectal liver tumour mouse model. Liver metastases were established by intrasplenic injection of C26-luc murine colon cancer cells. Based on the results of the toxicity assessment, an administration dose of 80% the maximum tolerated dose was selected. 188Re-liposomes were administered on day 1, when metastases of several hundred micrometers in diameter were observed. In the combination therapy group, 10 mg/kg sorafenib (co-developed and co-marketed by Bayer and Onyx Pharmaceuticals as Nexavar) was administered every other day for 1 week and the survival of mice was assessed. The tumor growth was more significantly inhibited in the 188Re-liposome plus sorafenib group compared with the 188Re-liposome alone, sorafenib alone and untreated normal saline groups (P=0.0000). Furthermore, 188Re-liposomes combined with sorafenib achieved higher survival rates compared with the 188Re-liposome alone, sorafenib alone and untreated normal saline groups (P=0.0000). These results support the use of combined radio-chemotherapy with 188Re-liposomes plus sorafenib as a viable treatment option in the adjuvant setting for liver metastases of colorectal cancer.

Single dose acute toxicity testing for N,N-bis(2-mercaptoethyl)-N',N' diethylethylenediamine in beagles.

N,N-Bis(2-mercaptoethyl)-N',N'-diethylenediamine (BMEDA) is used in the preparation of the (188)Re-BMEDA-liposome as a chelator to deliver rhenium 188 into liposomes. Although the safety of the (188)Re-BMEDA-liposome had been established, the use of BMEDA in preparing the liposome is of interest; however, an assessment of its safety is warranted. In this present work, we report on the acute toxicity study of BMEDA in beagles to identify doses causing no adverse effect and doses causing life-threatening toxicity. In a single dose 14-day systemic toxicity study conducted in beagles, BMEDA was without compound-related adverse effects at doses of up to 2mg/kg in a series of clinical observations and clinical pathology examinations. The results of these studies could aid in choosing doses for repeat-dose studies and in the selection of starting doses for Phase 1 human studies.