Systematic Review and Pharmacokinetic Meta-analysis of Doxorubicin Exposure in Transcatheter Arterial Chemoembolization and Doxorubicin-Eluted Beads Chemoembolization for Treatment of Unresectable Hepatocellular Carcinoma.

BACKGROUND: Almost 15 years after the introduction of transarterial chemoembolization (TACE) with drug-eluting beads (DEB-TACE) for hepatocellular carcinoma (HCC) therapy, the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) for doxorubicin have still not been systematically reviewed or meta-analyzed. OBJECTIVE: To conduct a systematic review and meta-analysis of available data and establish a reference range for Cmax and AUC of doxorubicin DEB-TACE and TACE, as well as explore the potential influence of microspheres' size and type on these parameters. METHODS: PubMed, EMBASE, and Web of Science were searched from August 1992 through December 2021. Studies measuring exposure parameters among HCC patients treated with doxorubicin DEB-TACE without restriction on language were included. Two independent reviewers extracted and unified data sets for pooled estimate analysis. The quality of the evidence was assessed via the Grading of Recommendations Assessment, Development and Evaluation framework. The ClinPK Statement checklist and Newcastle-Ottawa Scale (NOS) were used to determine the quality of studies. RESULTS: Out of 666 studies, 246 full-text were reviewed, and 8 studies entered the meta-analysis (120 patients). Cmax and AUC of doxorubicin were 7.52-fold (95% CI 7.65 to 7.42-fold; P < 0.0001) and 1.91-fold (95% CI 1.95 to 1.88-fold; P = 0.0001) lower with DEB-TACE compared to TACE. Significant reduction in pooled standardized mean difference (SMD) of Cmax and AUC was observed with DEB-TACE versus TACE in direct comparison analysis (- 2.93; 95% CI - 3.60 to - 2.26, P < 0.00001, and - 1.73 95% CI - 2.55 to - 0.91, P < 0.0001, respectively). Moreover, in DEB-TACE stratification analysis, small microspheres revealed higher Cmax, AUC and tumor response rate as well as lower complication rate. LIMITATION: The heterogeneity could not be completely addressed through sensitivity and stratification analysis. CONCLUSION: This meta-analysis provides exposure parameters of doxorubicin and justifies the advantage of DEB-TACE over TACE in terms of safety for patients with unresectable HCC. This study showed a marked association between the size of microsphere and exposure parameters of doxorubicin supporting the preference for small microspheres in DEB-TACE. The moderate and low quality of evidence is assigned to the Cmax and AUC, respectively.

Neutrophil depletion enhanced the Clostridium novyi-NT therapy in mouse and rabbit tumor models.

BACKGROUND: Hypoxia is a prominent feature of solid tumors and can function as fertile environment for oncolytic anaerobic bacteria such as Clostridium novyi-NT (C. novyi-NT) where it can induce tumor destruction in mice and patients. However, two major obstacles have limited its use, namely the host inflammatory response and the incomplete clearance of normoxic tumor areas. METHODS: In this study, we first used a subcutaneous tumor model of a glioblastoma (GBM) cell line in immunocompetent mice to investigate the local distribution of tumor hypoxia, kinetics of C. novyi-NT germination and spread, and the local host immune response. We subsequently applied the acquired knowledge to develop a C. novyi-NT therapy in an orthotopic rabbit brain tumor model. RESULTS: We found that local accumulation of granular leukocytes, mainly neutrophils, could impede the spread of bacteria through the tumor and prevent complete oncolysis. Depletion of neutrophils via anti-Ly6G antibody or bone marrow suppression using hydroxyurea significantly improved tumor clearance. We then applied this approach to rabbits implanted with an aggressive intracranial brain tumor and achieved long-term survival in majority of the animals without apparent toxicity. CONCLUSION: These results indicated that depleting neutrophils can greatly enhance the safety and efficacy of C. novyi-NT cancer therapy for brain tumors.

Preliminary evaluation of alpha-emitting radioembolization in animal models of hepatocellular carcinoma.

Hepatocellular carcinoma is the most common primary liver cancer and the fifth most frequently diagnosed cancer worldwide. Most patients with advanced disease are offered non-surgical palliative treatment options. This work explores the first alpha-particle emitting radioembolization for the treatment and monitoring of hepatic tumors. Furthermore, this works demonstrates the first in vivo simultaneous multiple-radionuclide SPECT-images of the complex decay chain of an [225Ac]Ac-labeled agent using a clinical SPECT system to monitor the temporal distribution. A DOTA chelator was modified with a lipophilic moiety and radiolabeled with the α-particle emitter Actinium-225. The resulting agent, [225Ac]Ac-DOTA-TDA, was emulsified in ethiodized oil and evaluated in vivo in mouse model and the VX2 rabbit technical model of liver cancer. SPECT imaging was performed to monitor distribution of the TAT agent and the free daughters. The [225Ac]Ac-DOTA-TDA emulsion was shown to retain within the HEP2G tumors and VX2 tumor, with minimal uptake within normal tissue. In the mouse model, significant improvements in overall survival were observed. SPECT-imaging was able to distinguish between the Actinium-225 agent (Francium-221) and the loss of the longer lived daughter, Bismuth-213. An α-particle emitting TARE agent is capable of targeting liver tumors with minimal accumulation in normal tissue, providing a potential therapeutic agent for the treatment of hepatocellular carcinoma as well as a variety of hepatic tumors. In addition, SPECT-imaging presented here supports the further development of imaging methodology and protocols that can be incorporated into the clinic to monitor Actinium-225-labeled agents.

Validation of a coupled electromagnetic and thermal model for estimating temperatures during magnetic nanoparticle hyperthermia.

PURPOSE: Alternating magnetic field (AMF) tissue interaction models are generally not validated. Our aim was to develop and validate a coupled electromagnetic and thermal model for estimating temperatures in large organs during magnetic nanoparticle hyperthermia (MNH). MATERIALS AND METHODS: Coupled finite element electromagnetic and thermal model validation was performed by comparing the results to experimental data obtained from temperatures measured in homogeneous agar gel phantoms exposed to an AMF at fixed frequency (155 ± 10 kHz). The validated model was applied to a three-dimensional (3D) rabbit liver built from computed tomography (CT) images to investigate the contribution of nanoparticle heating and nonspecific eddy current heating as a function of AMF amplitude. RESULTS: Computed temperatures from the model were in excellent agreement with temperatures calculated using the analytical method (error < 1%) and temperatures measured in phantoms (maximum absolute error <2% at each probe location). The 3D rabbit liver model for a fixed concentration of 5 mg Fe/cm3 of tumor revealed a maximum temperature ∼44 °C in tumor and ∼40 °C in liver at AMF amplitude of ∼12 kA/m (peak). CONCLUSION: A validated coupled electromagnetic and thermal model was developed to estimate temperatures due to eddy current heating in homogeneous tissue phantoms. The validated model was successfully used to analyze temperature distribution in complex rabbit liver tumor geometry during MNH. In future, model validation should be extended to heterogeneous tissue phantoms, and include heat sink effects from major blood vessels.

Evaluation of Hydrogen Peroxide Fumigation and Heat Treatment for Standard Emergency Arthropod Inactivation in BSL-3 Insectaries.

Climate change and global movements of people and goods have accelerated the spread of invasive species, including insects that vector infectious diseases, which threaten the health of more than half of the world's population. Increasing research efforts to control these diseases include the study of vector - pathogen interactions, involving the handling of pathogen-infected vector insects under biosafety level (BSL) 2 and 3 conditions. Like microbiology BSL-3 laboratories, BSL-3 insectaries are usually subjected to fixed-term or emergency room decontamination using recognized methods such as hydrogen peroxide (H2O2) or formaldehyde fumigation. While these procedures have been standardized and approved for the inactivation of diverse pathogens on surfaces, to date, there are no current standards for effective room-wide inactivation of insects in BSL-3 facilities in case of an emergency such as the accidental release of a large number of infected vectors. As H2O2 is often used for standard room decontamination in BSL-3 facilities, we evaluated H2O2 fumigation as a potential standard method for the safe, room-wide deactivation of insects in BSL-3 insectaries in comparison to heat treatment. To account for physiological diversity in vector insect species, six species from three different orders were tested. For the H2O2 fumigation we observed a strong but also varying resilience across all species. Lethal exposure time for the tested dipterans ranged from nine to more than 24 h. Furthermore, the coleopteran, Tribolium castaneum, did not respond to continuous H2O2 exposure for 48 h under standard room decontamination conditions. In contrast, temperatures of 50°C effectively killed all the tested species within 2 to 10 min. The response to lower temperatures (40-48°C) again showed a strong variation between species. In summary, results suggest that H2O2 fumigation, especially in cases where a gas generator is part of the laboratory equipment, may be used for the inactivation of selected species but is not suitable as a general emergency insect inactivation method under normal room decontamination conditions. In contrast, heat treatment at 48 to 50°C has the potential to be developed as an approved standard procedure for the effective inactivation of insects in BSL-3 facilities.

Combining Spectral CT Acquisition Methods for High-Sensitivity Material Decomposition.

Quantitative estimation of contrast agent concentration is made possible by spectral CT and material decomposition. There are several approaches to modulate the sensitivity of the imaging system to obtain the different spectral channels required for decomposition. Spectral CT technologies that enable this varied sensitivity include source kV-switching, dual-layer detectors, and source-side filtering (e.g., tiled spatial-spectral filters). In this work, we use an advanced physical model to simulate these three spectral CT strategies as well as hybrid acquisitions using all combinations of two or three strategies. We apply model-based material decomposition to a water-iodine phantom with iodine concentrations from 0.1 to 5.0 mg/mL. We present bias-noise plots for the different combinations of spectral techniques and show that combined approaches permit diversity in spectral sensitivity and improve low concentration imaging performance relative to the those strategies applied individually. Better ability to estimate low concentrations of contrast agent has the potential to reduce risks associated with contrast administration (by lowering dosage) or to extend imaging applications into targets with much lower uptake.

Performance Assessment of Texture Reproduction in High-Resolution CT.

Assessment of computed tomography (CT) images can be complex due to a number of dependencies that affect system performance. In particular, it is well-known that noise in CT is object-dependent. Such object-dependence can be more pronounced and extend to resolution and image textures with the increasing adoption of model-based reconstruction and processing with machine learning methods. Moreover, such processing is often inherently nonlinear complicating assessments with simple measures of spatial resolution, etc. Similarly, recent advances in CT system design have attempted to improve fine resolution details - e.g., with newer detectors, smaller focal spots, etc. Recognizing these trends, there is a greater need for imaging assessment that are considering specific features of interest that can be placed within an anthropomorphic phantom for realistic emulation and evaluation. In this work, we devise a methodology for 3D-printing phantom inserts using procedural texture generation for evaluation of performance of high-resolution CT systems. Accurate representations of texture have previously been a hindrance to adoption of processing methods like model-based reconstruction, and texture serves as an important diagnostic feature (e.g. heterogeneity of lesions is a marker for malignancy). We consider the ability of different systems to reproduce various textures (as a function of the intrinsic feature sizes of the texture), comparing microCT, cone-beam CT, and diagnostic CT using normal- and high-resolution modes. We expect that this general methodology will provide a pathway for repeatable and robust assessments of different imaging systems and processing methods.

Three-dimensional regions-of-interest-based intra-operative four-dimensional soft tissue perfusion imaging using a standard x-ray system with no gantry rotation: A simulation study for a proof of concept.

PURPOSE: Many interventional procedures aim at changing soft tissue perfusion or blood flow. One problem at present is that soft tissue perfusion and its changes cannot be assessed in an interventional suite because cone-beam computed tomography is too slow (it takes 4-10 s per volume scan). In order to address the problem, we propose a novel method called IPEN for Intra-operative four-dimensional soft tissue PErfusion using a standard x-ray system with No gantry rotation. METHODS: IPEN uses two input datasets: (a) the contours and locations of three-dimensional regions-of-interest (ROIs) such as arteries and sub-sections of cancerous lesions, and (b) a series of x-ray projection data obtained from an intra-arterial contrast injection to contrast enhancement to wash-out. IPEN then estimates a time-enhancement curve (TEC) for each ROI directly from projections without reconstructing cross-sectional images by maximizing the agreement between synthesized and measured projections with a temporal roughness penalty. When path lengths through ROIs are known for each x-ray beam, the ROI-specific enhancement can be accurately estimated from projections. Computer simulations are performed to assess the performance of the IPEN algorithm. Intra-arterial contrast-enhanced liver scans over 25 s were simulated using XCAT phantom version 2.0 with heterogeneous tissue textures and cancerous lesions. The following four sub-studies were performed: (a) The accuracy of the estimated TECs with overlapped lesions was evaluated at various noise (dose) levels with either homogeneous or heterogeneous lesion enhancement patterns; (b) the accuracy of IPEN with inaccurate ROI contours was assessed; (c) we investigated how overlapping ROIs and noise in projections affected the accuracy of the IPEN algorithm; and (d) the accuracy of the perfusion indices was assessed. RESULTS: The TECs estimated by IPEN were sufficiently accurate at a reference dose level with the root-mean-square deviation (RMSD) of 0.0027 ± 0.0001 cm-1 or 13 ± 1 Hounsfield unit (mean ± standard deviation) for the homogeneous lesion enhancement and 0.0032 ± 0.0005 cm-1 for the heterogeneous enhancement (N = 20 each). The accuracy was degraded with decreasing doses: The RMSD with homogeneous enhancement was 0.0220 ± 0.0003 cm-1 for 20% of the reference dose level. Performing 3 × 3 pixel averaging on projection data improved the RMSDs to 0.0051 ± 0.0002 cm-1 for 20% dose. When the ROI contours were inaccurate, smaller ROI contours resulted in positive biases in TECs, whereas larger ROI contours produced negative biases. The bias remained small, within ± 0.0070 cm-1 , when the Sorenson-Dice coefficients (SDCs) were larger than 0.81. The RMSD of the TEC estimation was strongly associated with the condition of the problem, which can be empirically quantified using the condition number of a matrix A z that maps a vector of ROI enhancement values z to projection data and a weighted variance of projection data: a linear correlation coefficient (R) was 0.794 (P < 0.001). The perfusion index values computed from the estimated TECs agreed well with the true values (R ≥ 0.985, P < 0.0001). CONCLUSION: The IPEN algorithm can estimate ROI-specific TECs with high accuracy especially when 3 × 3 pixel averaging is applied, even when lesion enhancement is heterogeneous, or ROI contours are inaccurate but the SDC is at least 0.81.

tRNAs and tRNA fragments as modulators of cardiac and skeletal muscle function.

Transfer RNAs (tRNAs) and their processing enzymes have long-recognized roles in cardiac and skeletal muscle pathophysiology. Recently, tRNA fragments have emerged as a new class of non-coding RNAs involved in the regulation of cell function. In this review, we provide a synopsis of the molecular processes that regulate the biogenesis, post-transcriptional regulation and functional roles of tRNAs in cardiac and skeletal muscle. In addition, we list the (dys)regulated expression profiles and putative functional roles of tRNA-derived small RNAs in the heart and skeletal muscle. Finally, the technical challenges surrounding tRNA research are discussed alongside suggestions to advance research in this field.

Increased uptake of doxorubicin by cells undergoing heat stress does not explain its synergistic cytotoxicity with hyperthermia.

Purpose: A proposed mechanism for the enhanced effectiveness of hyperthermia and doxorubicin (Dox) combinations is increased intracellular Dox concentrations resulting from heat-induced cell stress. The purpose of this study was to determine whether specific varied Dox and heat combinations produce measurable effects greater than the additive combination, and whether these effects can be attributed to heat-induced increases in intracellular Dox concentrations. Methods: HCT116, HT29 and CT26 cells were exposed to Dox and water bath heating independently. A clonogenic survival assay was used to determine cell killing and intracellular Dox concentrations were measured in HCT116 cells with mass spectrometry. Cells were exposed to heating at 42 °C (60 min) and 0.5 µg/ml of Dox at varying intervals. Synergy was determined by curve-fitting and isobologram analysis. Results: All cell lines displayed synergistic effects of combined heating and Dox. A maximum synergistic effect was achieved with simultaneous cell exposure to Dox and heat. For exposures at 42 °C, the synergistic effect was most pronounced at Dox concentrations <0.5 µg/ml. Increased intracellular concentrations of Dox in HCT116 cells caused by heat-stress did not generate a concomitant thermal enhancement. Conclusions: Simultaneous exposure of HCT116 cells to heating and Dox is more effective than sequential exposure. Heat-induced cell responses are accompanied by increased intracellular Dox concentrations; however, clonogenic survival data do not support this as the cause for synergistic cytotoxicity.

Theranostic application of lipiodol for transarterial chemoembolization in a VX2 rabbit liver tumor model.

The goal of this study was to investigate the role of Lipiodol as a tumor-specific imaging biomarker to determine therapeutic efficacy of cTACE and investigate its inter-dependency with tumor perfusion using radiological-pathological correlation in an animal model of liver cancer. METHODS: A total of N=36 rabbits were implanted in the left lobe of the liver with VX2 tumors, treated with cTACE using doxorubicin suspended in Lipiodol, and randomly sacrificed at 24 h, 7 days, or 20 days post-TACE. Unenhanced and contrast-enhanced CT scans including a perfusion protocol were obtained before cTACE and immediately before sacrifice. Tumor vascularity and Lipiodol deposition within tumors and hepatic tissue (non-target deposits) were quantified using 3D quantitative assessment tools and measurements of arterial flow, portal flow, and perfusion index (PI). After sacrifice histologic staining, including hematoxylin and eosin (H&E), CD31, and Oil Red O (ORO) were performed on tumor and liver samples to evaluate necrosis, microvascular density (MVD), and Lipiodol retention over time. Transmission electron microscopy (TEM) was performed to assess Lipiodol deposition and clearance over time. RESULTS: All cTACE procedures were carried out successfully except for one, which was excluded from further analysis. Twenty-four hours post-TACE, tumor PI (p=0.04) was significantly decreased, which was maintained at 7 days (p=0.003), but not at 20 days (p=0.4). A strong correlation (R2 = 0.894) was found between the volume of enhancing tumor tissue at baseline and Lipiodol-positive tumor volume post-TACE. Both ORO and TEM showed deposition of Lipiodol across all imaging time points within the VX2 tumors. However, gradual and ultimately near-complete Lipiodol washout was observed over time in the non-tumoral liver. MVD decreased between 24 h and 7 days post-TACE, and then increased 20 days post-TACE (both p<0.01). CONCLUSIONS: Our data provide radiology-pathology evidence for the function of Lipiodol as a theranostic, tumor-specific drug delivery agent because it is both imageable and tumor-seeking, whereby it is preferentially taken up and retained by tumor cells. Those tumor-specific functions also enable Lipiodol to act as an imaging biomarker for the therapeutic efficacy of cTACE. Together with volumetric quantification of tumor vascularization on CT, Lipiodol could be used as a predictor of a patient's response to cTACE and contribute to the therapeutic management of patients with liver cancer.

Human skin long noncoding RNA WAKMAR1 regulates wound healing by enhancing keratinocyte migration.

An increasing number of studies reveal the importance of long noncoding RNAs (lncRNAs) in gene expression control underlying many physiological and pathological processes. However, their role in skin wound healing remains poorly understood. Our study focused on a skin-specific lncRNA, LOC105372576, whose expression was increased during physiological wound healing. In human nonhealing wounds, however, its level was significantly lower compared with normal wounds under reepithelialization. We characterized LOC105372576 as a nuclear-localized, RNAPII-transcribed, and polyadenylated lncRNA. In keratinocytes, its expression was induced by TGF-ß signaling. Knockdown of LOC105372576 and activation of its endogenous transcription, respectively, reduced and increased the motility of keratinocytes and reepithelialization of human ex vivo skin wounds. Therefore, LOC105372576 was termed "wound and keratinocyte migration-associated lncRNA 1" (WAKMAR1). Further study revealed that WAKMAR1 regulated a network of protein-coding genes important for cell migration, most of which were under the control of transcription factor E2F1. Mechanistically, WAKMAR1 enhanced E2F1 expression by interfering with E2F1 promoter methylation through the sequestration of DNA methyltransferases. Collectively, we have identified a lncRNA important for keratinocyte migration, whose deficiency may be involved in the pathogenesis of chronic wounds.

Temperature-controlled power modulation compensates for heterogeneous nanoparticle distributions: a computational optimization analysis for magnetic hyperthermia.

PURPOSE: To study, with computational models, the utility of power modulation to reduce tissue temperature heterogeneity for variable nanoparticle distributions in magnetic nanoparticle hyperthermia. METHODS: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes' bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods. RESULTS: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating. CONCLUSIONS: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment.

Successful liver-directed gene delivery by ERCP-guided hydrodynamic injection (with videos).

BACKGROUND AND AIMS: A simple, safe, targeted, and efficient in vivo DNA delivery system is necessary for clinical-grade liver-targeted gene therapy in humans. Intravascular hydrodynamic gene delivery has been investigated in large animal models, but translation to humans has been hampered by its technical challenges, invasiveness, and potential for significant cardiovascular adverse events. We posited that intrabiliary delivery of DNA plasmids via ERCP-guided hydrodynamic injection could overcome these obstacles. METHODS: Twelve pigs (40-50 kg) were divided into 3 groups (4 per group) and survived 21, 30, or 60 days. ERCP was performed by inflating a balloon catheter in the common hepatic duct and creating a closed space between it and the liver parenchyma. Last, a solution composed of plasmid/sleeping beauty (SB) mix was injected under pressure through the catheter into the closed space. Swine were killed at the 3 different time points and liver tissue harvested. Plasmid DNA expression and functional translated protein expression were assessed. RESULTS: ERCP-guided hydrodynamic delivery of naked plasmid DNA facilitated by pCytomegalovirus-Sleep Beauty (pCMV-SB) transposons was technically feasible and devoid of cardiovascular and local adverse events in all 12 pigs. Furthermore, plasmid DNA (both single and combination) was successfully transferred into swine hepatocytes in all 12 pigs. Additionally, stable integration of the DNA constructs in hepatocyte genomic DNA was reliably noted at all 3 time points. In the 4 swine that were kept alive to 60 days, successful genomic integration and subsequent protein expression was observed in the targeted liver tissue. CONCLUSIONS: ERCP-guided hydrodynamic delivery of gene therapy may usher in the next chapter in gene therapy with the potential to impact a variety of single-gene, complex genetic, and epigenetic liver diseases. It also raises the possibility that other nucleic acid therapeutics (microRNA, lncRNA, siRNA, shRNA) could similarly be delivered.

Low-Dose CT Perfusion of the Liver using Reconstruction of Difference.

Liver CT perfusion (CTP) is used in the detection, staging, and treatment response analysis of hepatic diseases. Unfortunately, CTP radiation exposures is significant, limiting more widespread use. Traditional CTP data processing reconstructs individual temporal samples, ignoring a large amount of shared anatomical information between temporal samples, suggesting opportunities for improved data processing. We adopt a prior-image-based reconstruction approach called Reconstruction of Difference (RoD) to enable low-exposure CTP acquisition. RoD differs from many algorithms by directly estimating the attenuation changes between the current patient state and a prior CT volume. We propose to use a high-fidelity unenhanced baseline CT image to integrate prior anatomical knowledge into subsequent data reconstructions. Using simulation studies based on a 4D digital anthropomorphic phantom with realistic time-attenuation curves, we compare RoD with conventional filtered-backprojection, penalized-likelihood estimation, and prior image penalized-likelihood estimation. We evaluate each method in comparisons of reconstructions at individual time points, accuracy of estimated time-attenuation curves, and in an analysis of common perfusion metric maps including hepatic arterial perfusion, hepatic portal perfusion, perfusion index, and time-to-peak. Results suggest that RoD enables significant exposure reductions, outperforming standard and more sophisticated model-based reconstruction, making RoD a potentially important tool to enable low-dose liver CTP.

Demonstration of Safety and Feasibility of Hydrogel Marking of the Pancreas-Duodenum Interface for Image Guided Radiation Therapy (IGRT) in a Porcine Model: Implications in IGRT for Pancreatic Cancer Patients.

PURPOSE: To test the feasibility and safety of injecting a high-contrast hydrogel marker at the head of the pancreas (HOP) and duodenum interface and assesses the marker visibility on cone beam computed tomography (CBCT) to localize this important boundary during image guided radiation therapy in a porcine model. METHODS AND MATERIALS: This was a 2-stage study. The feasibility/visibility stage evaluated the ability to place the hydrogel using endoscopic ultrasound guidance on 8 swine (4 euthanized at post-injection day 8, 4 euthanized at post-injection day 22) and assessed the quality of visibility of the marked location on CBCT in the longer-surviving group. The risk assessment stage evaluated the toxicity of targeted intrapancreatic injections (3 swine) and intramural duodenal wall injections (3 swine) to assess toxicity of a misplaced hydrogel injection. All swine underwent postmortem examination and histopathologic studies. RESULTS: The HOP-duodenum interface was successfully marked using hydrogel in 6 of the 8 swine. Histopathologic examination of the 6 successful hydrogel injections showed mild/minimal (4 cases) or moderate (2 cases) reactive inflammation isolated to the injection site. Of the 4 swine survived to 22 days, 3 demonstrated successful hydrogel placement at the HOP-duodenum interface, and this marked location was clearly visible for positional guidance on CBCT. There was no evidence of pancreatitis or duodenal toxicity in the swine undergoing targeted intrapancreatic or intramural duodenum injections for the risk assessment stage. CONCLUSIONS: We demonstrate the feasibility and safety of injecting a hydrogel marker to highlight the HOP-duodenum interface that has acceptable visibility on CBCT. This technique, translated to humans, enables on-board visualization of this important boundary between the radiation target and dose-limiting, radiosensitive duodenum, facilitating efforts to safely deliver dose-escalated radiation therapy.

Image-guided thermal therapy with a dual-contrast magnetic nanoparticle formulation: A feasibility study.

PURPOSE/OBJECTIVE: The aim of this study was to develop and investigate the properties of a magnetic iron oxide nanoparticle-ethiodised oil formulation for image-guided thermal therapy of liver cancer. MATERIALS AND METHODS: The formulation comprises bionised nano-ferrite (BNF) nanoparticles suspended in ethiodised oil, emulsified with polysorbate 20 (BNF-lip). Nanoparticle size was measured via photon correlation spectroscopy and transmission electron microscopy. In vivo thermal therapy capability was tested in two groups of male Foxn1(nu) mice bearing subcutaneous HepG2 xenograft tumours. Group I (n = 12) was used to screen conditions for group II (n = 48). In group II, mice received one of BNF-lip (n = 18), BNF alone (n = 16), or PBS (n = 14), followed by alternating magnetic field (AMF) hyperthermia, with either varied duration (15 or 20 min) or amplitude (0, 16, 20, or 24 kA/m). Image-guided fluoroscopic intra-arterial injection of BNF-lip was tested in New Zealand white rabbits (n = 10), bearing liver VX2 tumours. The animals were subsequently imaged with CT and 3 T MRI, up to 7 days post-injection. The tumours were histopathologically evaluated for distribution of BNF-lip. RESULTS: The BNF showed larger aggregate diameters when suspended in BNF-lip, compared to clear solution. The BNF-lip formulation produced maximum tumour temperatures with AMF >20 kA/m and showed positive X-ray visibility and substantial shortening of T1 and T2 relaxation time, with sustained intratumoural retention up to 7 days post-injection. On pathology, intratumoural BNF-lip distribution correlated well with CT imaging of intratumoural BNF-lip distribution. CONCLUSION: The BNF-lip formulation has favourable thermal and dual imaging capabilities for image-guided thermal therapy of liver cancer, suggesting further exploration for clinical applications.

Evaluation of 70-150-µm doxorubicin-eluting beads for transcatheter arterial chemoembolization in the rabbit liver VX2 tumour model.

AIM: To evaluate the pharmacokinetic profile (PK) and embolization effect of 70-150-µm doxorubicin eluting beads (DEBs) following intra-arterial injection (i.a.) in the rabbit liver VX2 tumour model. MATERIALS AND METHODS: In this ACUC-approved study, 25 white New Zealand rabbits were randomly assigned into a small DEB group (SDB, n = 7, 70-150-µm DEBs), large DEB group (LDB, n = 7, 100-300-µm DEBs), untreated controls (n = 7), and doxorubicin controls (n = 4, without tumour, received i.a. 12.5 mg doxorubicin). Plasma PK was assessed up to 180 min post-injection. Drug tissue and liver enzyme levels, radiologic tumor response and histopathologic tumour necrosis were assessed at 7 days. RESULTS: Mean tumour doxorubicin concentrations were 922.83 nM (SD = 722.05) and 361.48 nM (SD = 473.23) for the SDB and LDB, respectively (p = 0.005). There was no statistically significant difference in tumour doxorubicinol, plasma doxorubicin and doxorubicinol PK values. More beads were observed in the SDB tumours (p = 0.01). Liver enzymes increased and gradually declined over the observation period, with significantly higher values in the SDB. CONCLUSION: In this preclinical study, plasma PK of i.a.-injected 70-150-µm DEBs was not different than that of 100-300-µm DEBs. More beads and higher tissue doxorubicin levels were observed in the SDB tumours. KEY POINTS: • Small and large doxorubicin-eluting beads show similar plasma pharmacokinetic profiles. • Higher tissue doxorubicin levels were observed in the small bead group. • Liver enzymes were overall significantly higher in the small bead group.

Identification of novel non-coding RNA-based negative feedback regulating the expression of the oncogenic transcription factor GLI1.

Non-coding RNAs are a complex class of nucleic acids, with growing evidence supporting regulatory roles in gene expression. Here we identify a non-coding RNA located head-to-head with the gene encoding the Glioma-associated oncogene 1 (GLI1), a transcriptional effector of multiple cancer-associated signaling pathways. The expression of this three-exon GLI1 antisense (GLI1AS) RNA in cancer cells was concordant with GLI1 levels. siRNAs knockdown of GLI1AS up-regulated GLI1 and increased cellular proliferation and tumor growth in a xenograft model system. Conversely, GLI1AS overexpression decreased the levels of GLI1, its target genes PTCH1 and PTCH2, and cellular proliferation. Additionally, we demonstrate that GLI1 knockdown reduced GLI1AS, while GLI1 overexpression increased GLI1AS, supporting the role of GLI1AS as a target gene of the GLI1 transcription factor. Activation of TGFß and Hedgehog signaling, two known regulators of GLI1 expression, conferred a concordant up-regulation of GLI1 and GLI1AS in cancer cells. Finally, analysis of the mechanism underlying the interplay between GLI1 and GLI1AS indicates that the non-coding RNA elicits a local alteration of chromatin structure by increasing the silencing mark H3K27me3 and decreasing the recruitment of RNA polymerase II to this locus. Taken together, the data demonstrate the existence of a novel non-coding RNA-based negative feedback loop controlling GLI1 levels, thus expanding the repertoire of mechanisms regulating the expression of this oncogenic transcription factor.