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.

Therapeutic efficacy of 188Re-liposome in a C26 murine colon carcinoma solid tumor model.

Nanoliposomes are good drug delivery systems that allow the encapsulation of drugs into vesicles for their delivery. The objective of this study is to investigate the therapeutic efficacy of a new radio-therapeutics of (188)Re-labeled pegylated liposome in a C26 murine colon carcinoma solid tumor model. The safety of (188)Re-liposome was evaluated before radiotherapy treatment. The anti-tumor effect of (188)Re-liposome was assessed by tumor growth inhibition, survival ratio and ultrasound imaging. Apoptotic marker in tumor was also evaluated by the TUNEL (terminal deoxynucleotidyl transferase biotin-dUTP nick-end labeling) method after injection of (188)Re-liposome. The group treated with (188)Re-liposome displayed slight loss in body weight and decrease in white blood cell (WBC) count 7 to 14 days post-injection. With respect to therapeutic efficacy, the tumor-bearing mice treated with (188)Re-liposome showed better mean tumor growth inhibition rate (MGI) and longer median survival time (MGI = 0.140; 80 day) than those treated with anti-cancer drug 5-FU (MGI = 0.195; 69 day) and untreated control mice (MGI = 0.413; 48 day). The ultrasound imaging showed a decrease in both tumor volume and number of blood vessels. There were significantly more apoptotic nuclei (TUNEL-positive) in (188)Re-liposome-treated mice at 8 h after treatment than in control mice. These results evidenced the potential benefits achieved by oncological application of the radio-therapeutics (188)Re-liposome for adjuvant cancer treatment.

Preliminary evaluation of acute toxicity of (188) Re-BMEDA-liposome in rats.

Liposomes can selectively target cancer sites and carry payloads, thereby improving diagnostic and therapeutic effectiveness and reducing toxicity. To evaluate therapeutic strategies, it is essential to use animal models reflecting important safety aspects before clinical application. The objective of this study was to investigate acute radiotoxicity of ¹88Re-N,N-bis (2-mercaptoethyl)-N',N'-diethylethylenediamine (BMEDA)-labeled pegylated liposomes (¹88Re-BMEDA-liposome) in Sprague-Dawley rats. Rats were administered with ¹88Re-BMEDA-liposome, normal saline as blank or non-radioactive liposome as vehicle control via intravenous injection and observed for 14 days. Examinations were conducted with respect to mortality, clinical signs, food consumption, body weight and hematological and biochemical analyses. In addition, gross necropsy, histopathological examinations and cytogenetic analyses were also performed. None of the rats died and no clinical sign was observed during the 14-day study period. Rats administered with ¹88Re-BMEDA-liposome at dosage of 185 MBq displayed a significant weight loss compared with the control from study day (SD) 1 to SD 4, and the white blood cell count reduced to 5-10% of initial value (female: 18.55 ± 6.58 to 0.73 ± 0.26 x 10³ µl⁻¹; male: 14.52 ± 5.12 to 1.43 ± 0.54 x 10³ µl⁻¹) 7 days-post injection, but were found to have recovered on SD 15. There were no significant differences in biochemical parameters and histopathological assessments between the ¹88Re-BMEDA-liposome-treated and control groups. The frequencies of dicentric chromosomes were associated with dosage of ¹88Re-BMEDA-liposome. The information generated from this study on acute toxicity will serve as a safety reference for further subacute toxicity study in rats and human clinical trials.

Pharmacokinetics, micro-SPECT/CT imaging and therapeutic efficacy of (188)Re-DXR-liposome in C26 colon carcinoma ascites mice model.

The pharmacokinetics and internal radionuclide therapy of intraperitoneally administrated (188)Re-N,N-bis(2-mercaptoethyl)-N',N'-diethylethylenediamine (BMEDA)-labeled pegylated liposomal doxorubicin ((188)Re-DXR-liposome) were investigated in the C26 murine colon carcinoma ascites mouse model. After intraperitoneal administration of the nanotargeted bimodality (188)Re-DXR-liposome, the ascites and tumor accumulation of the radioactivity were observed, the levels of radioactivity within the ascites were maintained at relatively higher levels before 48 h and the levels of radioactivity in the tumor were maintained at steady levels after 4 h. The AUC((o-->infinity)) of (188)Re-DXR-liposome in blood, ascites and tumor was 9.3-, 4.2- and 4.7-fold larger than that of (188)Re-BMEDA, respectively. The maximum tolerated dose of intraperitoneally administrated (188)Re-DXR-liposome was determined in normal BALB/c mice. The survival, tumor and ascites inhibition of mice after (188)Re-DXR-liposome (22.2 MBq of (188)Re, 5 mg/kg of DXR) treatment were evaluated. Consequently, radiochemotherapeutics of (188)Re-DXR-liposome attained better survival time, tumor and ascites inhibition (decreased by 49% and 91% at 4 days after treatment; P<.05) in mice than radiotherapeutics of (188)Re-liposome or chemotherapeutics of Lipo-Dox did. Therefore, intraperitoneal administration of novel (188)Re-DXR-liposome could provide a benefit and promising strategy for delivery of passive nanotargeted bimodality radiochemotherapeutics in oncology applications.

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.

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.

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.

Dosimetric evaluation of nanotargeted (188)Re-liposome with the MIRDOSE3 and OLINDA/EXM programs.

OBJECTIVE: The OLINDA/EXM computer code was created as a replacement for the widely used MIRDOSE3 code for radiation dosimetry in nuclear medicine. A dosimetric analysis with these codes was performed to evaluate nanoliposomes as carriers of radionuclides ((188)Re-liposomes) in colon carcinoma-bearing mice. METHODS: Pharmacokinetic data for (188)Re-N, N-bis (2-mercaptoethyl)-N',N'-diethylethylenediamine ((188)Re-BMEDA) and (188)Re-liposome were obtained for estimation of absorbed doses in normal organs. Radiation dose estimates for normal tissues were calculated using the MIRDOSE3 and OLINDA/EXM programs for a colon carcinoma solid tumor mouse model. RESULTS: Mean absorbed doses derived from(188)Re-BMEDA and (188)Re-liposome in normal tissues were generally similar as calculated by MIRDOSE3 and OLINDA/EXM programs. One notable exception to this was red marrow, wherein MIRDOSE3 resulted in higher absorbed doses than OLINDA/EXM (1.53- and 1.60-fold for (188)Re-BMEDA and (188)Re-liposome, respectively). CONCLUSIONS: MIRDOSE3 and OLINDA have very similar residence times and organ doses. Bone marrow doses were estimated by designating cortical bone rather than bone marrow as a source organ. The bone marrow doses calculated by MIRDOSE3 are higher than those by OLINDA. If the bone marrow is designated as a source organ, the doses estimated by MIRDOSE3 and OLINDA programs will be very similar.

Comparative therapeutic efficacy of rhenium-188 radiolabeled-liposome and 5-fluorouracil in LS-174T human colon carcinoma solid tumor xenografts.

Nanoliposomes are important carriers capable of packaging drugs for various delivery applications. Rhenium-188-radiolabeled liposome ((188)Re-liposome) has potential for radiotherapy and diagnostic imaging. To evaluate the targeting of (188)Re-liposome, biodistribution, microSPECT/CT, whole-body autoradiography (WBAR), and pharmacokinetics were performed in LS-174T human tumor-bearing mice. The comparative therapeutic efficacy of (188)Re-liposome and 5-fluorouracil (5-FU) was assessed according to inhibition of tumor growth and the survival ratio. The highest uptake of (188)Re-liposome in LS-174T tumor was found at 24 hours by biodistribution and microSPECT/CT imaging, showing a positive correlation for tumor targeting of (188)Re-liposome using the Pearson's correlation analysis (r=0.997). Pharmacokinetics of (188)Re-liposome showed the properties of high circulation time and high bioavailability (mean residence time [MRT]=18.8 hours, area under the curve [AUC]=1371%ID/g·h). For therapeutic efficacy, the tumor-bearing mice treated with (188)Re-liposome (80% maximum tolerated dose [MTD], 23.7 MBq) showed better tumor growth inhibition and longer survival time than those treated with 5-FU (80% MTD, 144 mg/kg). The median survival time for mice treated with (188)Re-liposome (58.5 days; p<0.05) was significantly better than those of 5-FU (48.25 days; p>0.05) and normal saline-treated mice (43.63 days). Dosimetry study revealed that the (188)Re-liposome did not lead to high absorbed doses in normal tissue, but did in small tumors. These results of imaging and biodistribution indicated the highly specific accumulation of tumor after intravenous (i.v.) injection of (188)Re-liposome. The therapeutic efficacy of radiotherapeutics of (188)Re-liposome have been confirmed in a LS-174T solid tumor animal model, which points to the potential benefit and promise of passive nanoliposome delivered radiotherapeutics for cancer treatment.

Near-infrared light-responsive core-shell nanogels for targeted drug delivery.

A near-infrared light-responsive drug delivery platform based on Au-Ag nanorods (Au-Ag NRs) coated with DNA cross-linked polymeric shells was constructed. DNA complementarity has been applied to develop a polyacrylamide-based sol-gel transition system to encapsulate anticancer drugs into the gel scaffold. The Au-Ag NR-based nanogels can also be readily functionalized with targeting moieties, such as aptamers, for specific recognition of tumor cells. When exposed to NIR irradiation, the photothermal effect of the Au-Ag NRs leads to a rapid rise in the temperature of the surrounding gel, resulting in the fast release of the encapsulated payload with high controllability. In vitro study confirmed that aptamer-functionalized nanogels can be used as drug carriers for targeted drug delivery with remote control capability by NIR light with high spatial/temporal resolution.

Pharmacokinetics and dosimetry of (111)In/(188)Re-labeled PEGylated liposomal drugs in two colon carcinoma-bearing mouse models.

PEGylated liposomes are important drug carriers for nanomedicine cancer therapy. PEGylated liposomes can encapsulate radio- and chemo-drugs and passively target tumor sites via enhanced permeability and retention effect. This study estimated the pharmacokinetics and dosimetry after administration of radio-chemotherapeutics ((111)In-labeled vinorelbine [VNB]-encapsulated liposomes, InVNBL, and (188)Re-labeled doxorubicin [DXR]-encapsulated liposomes, ReDXRL) for radionuclide therapy in two colon carcinoma-bearing mouse models. A C26 colon carcinoma tumor/ascites mouse model and a subcutaneous solid tumor-bearing mouse model were employed. Biodistribution studies of InVNBL and ReDXRL after intraperitoneal administration in tumor/ascites-bearing mice (protocol A) and intravenous administration in subcutaneous solid tumor-bearing mice (protocol B) were performed. The radiation dose to normal tissues and tumors were calculated based on the results of distribution studies in mice, using the OLINDA/EXM program. The cumulated activities in most organs after administration of InVNBL in either the tumor/ascites-bearing mice (protocol A) or the subcutaneous solid tumor-bearing mice (protocol B) were higher than those of ReDXRL. Higher tumor-to-normal-tissues absorption dose ratios (T/NTs) were observed after administration of InVNBL than those of ReDXRL for protocol A. The T/NTs for the liver, spleen, and red marrow after injection of InVNBL for protocol B were similar to those of ReDXRL. The critical organ was found to be red marrow, and thus the red marrow absorption dose defined the recommended maximum administration activity of these liposomal drugs. Characterization of pharmacokinetics and dosimetry is needed to select the appropriate radiotherapeutics for specific tumor treatment applications. The results suggest that InVNBL is a promising therapeutic agent, which is as good as ReDXRL, in two mouse tumor models.

Biodistribution and pharmacokinetics of 188Re-liposomes and their comparative therapeutic efficacy with 5-fluorouracil in C26 colonic peritoneal carcinomatosis mice.

BACKGROUND: Nanoliposomes are designed as carriers capable of packaging drugs through passive targeting tumor sites by enhanced permeability and retention (EPR) effects. In the present study the biodistribution, pharmacokinetics, micro single-photon emission computed tomography (micro-SPECT/CT) image, dosimetry, and therapeutic efficacy of (188)Re-labeled nanoliposomes ((188)Re-liposomes) in a C26 colonic peritoneal carcinomatosis mouse model were evaluated. METHODS: Colon carcinoma peritoneal metastatic BALB/c mice were intravenously administered (188)Re-liposomes. Biodistribution and micro-SPECT/CT imaging were performed to determine the drug profile and targeting efficiency of (188)Re-liposomes. Pharmacokinetics study was described by a noncompartmental model. The OLINDA|EXM computer program was used for the dosimetry evaluation. For therapeutic efficacy, the survival, tumor, and ascites inhibition of mice after treatment with (188)Re-liposomes and 5-fluorouracil (5-FU), respectively, were evaluated and compared. RESULTS: In biodistribution, the highest uptake of (188)Re-liposomes in tumor tissues (7.91% ± 2.02% of the injected dose per gram of tissue [%ID/g]) and a high tumor to muscle ratio (25.8 ± 6.1) were observed at 24 hours after intravenous administration. The pharmacokinetics of (188)Re-liposomes showed high circulation time and high bioavailability (mean residence time [MRT] = 19.2 hours, area under the curve [AUC] = 820.4%ID/g*h). Micro-SPECT/CT imaging of (188)Re-liposomes showed a high uptake and targeting in ascites, liver, spleen, and tumor. The results were correlated with images from autoradiography and biodistribution data. Dosimetry study revealed that the (188)Re-liposomes did not cause high absorbed doses in normal tissue but did in small tumors. Radiotherapeutics with (188)Re-liposomes provided better survival time (increased by 34.6% of life span; P < 0.05), tumor and ascites inhibition (decreased by 63.4% and 83.3% at 7 days after treatment; P < 0.05) in mice compared with chemotherapeutics of 5-fluorouracil (5-FU). CONCLUSION: The use of (188)Re-liposomes for passively targeted tumor therapy had greater therapeutic effect than the currently clinically applied chemotherapeutics drug 5-FU in a colonic peritoneal carcinomatosis mouse model. This result suggests that (188)Re-liposomes have potential benefit and are safe in treating peritoneal carcinomatasis of colon cancer.

MicroSPECT/CT imaging and pharmacokinetics of 188Re-(DXR)-liposome in human colorectal adenocarcinoma-bearing mice.

Nanoliposome can be designed as a drug delivery carrier to improve the pharmacological and therapeutic properties of drug administration. (188)Re-labeled nanoliposomes are useful for diagnostic imaging as well as for targeted radionuclide therapy. In this study, the in vivo nuclear imaging, pharmacokinetics and biodistribution of administered nanoliposomes were investigated as drug and radionuclide carriers for targeting solid tumor via intravenous (i.v.) administration. The radiotherapeutics ((188)Re-liposome) and radiochemotherapeutics ((188)Re-DXR-liposome) were i.v. administered to nude mice bearing human HT-29 colorectal adenocarcinoma xenografts. (188)Re-liposome and (188)Re-DXR-liposomes show similar biodistribution profile; both have higher tumor uptake, higher blood retention time, and lower excretion rate than (188)Re-N,N-bis(2-mercaptoethyl)-N',N'-diethylenediamine (BMEDA). In contrast to tumor uptake, the area under the curve (AUC) value of tumor for (188)Re-liposome and (188)Re-DXR-liposome was 16.5- and 11.5-fold higher than that of free (188)Re-BMEDA, respectively. Additionally, (188)Re-liposome and (188)Re-DXR-liposome had a higher tumor-to-muscle ratio at 24 h (14.4+/-2 .7 and 17.14+/-4.1, respectively) than (188)Re-BMEDA (1.6+/-0.1). The tumor targeting and distribution of (188)Re-(DXR)-liposome (representing (188)Re-DXR-liposome and (188)Re-liposome) can also be acquired by signal photon-emission computed tomography/computed tomography images as well as whole body autoradiograph. These results suggest that (188)Re-(DXR)-liposomes are potentially promising agents for passive targeting treatment of malignant disease.

Comparative dosimetric evaluation of nanotargeted (188)Re-(DXR)-liposome for internal radiotherapy.

UNLABELLED: A dosimetric analysis was performed to evaluate nanoliposomes as carriers of radionuclides ((188)Re-liposomes) and radiochemotherapeutic drugs [(188)Re-doxorubicin (DXR)-liposomes] in internal radiotherapy for colon carcinoma, as evaluated in mice. METHODS: Pharmacokinetic data for (188)Re-N, N-bis (2-mercaptoethyl)-N',N'-diethylethylenediamine (BMEDA), (188)Re-liposome, and (188)Re-DXR-liposome were obtained for the estimation of absorbed doses in tumors and normal organs. Two colon carcinoma mouse models were employed: subcutaneous growing solid tumor and malignant ascites pervading tumor models. Radiation-dose estimates for normal tissues and tumors were calculated by using the OLINDA/EXM program. An evaluation of a recommended maximum administered activity (MAA) for the nanotargeted drugs was also made. RESULTS: Mean absorbed doses derived from (188)Re-liposome and (188)Re-DXR-liposome in normal tissues were generally similar to those from (188)Re-BMEDA in intraperitoneal and intravenous administration. Tissue-absorbed dose in the liver was 0.24-0.40 and 0.17-0.26 (mGy/MBq) and in red marrow was 0.033-0.050 and 0.038-0.046 (mGy/MBq), respectively, for (188)Re-liposome and (188)Re-DXR-liposome. Tumor-absorbed doses for the nanotargeted (188)Re-liposome and (188)Re-DXR-liposome were higher than those of (188)Re-BMEDA for both routes of administration (4-26-fold). Dose to red marrow defined the recommended MAA. CONCLUSIONS: Our results suggest that radionuclide and chemoradiotherapeutic passive targeting delivery, using nanoliposomes as the carrier, is feasible and promising in systemic-targeted radionuclide therapy.