Transarterial Embolization of Liver Cancer in a Transgenic Pig Model

Intra-arterial Pressure-Enabled Drug Delivery Significantly Increases Penetration of Glass Microspheres in a Porcine Liver Tumor Model

PURPOSE

To test the hypothesis that Pressure-Enabled Drug Delivery (PEDD) would improve the delivery of surrogate therapeutic glass microspheres (GMs) via hepatic artery infusion to liver tumors when compared with a conventional endhole microcatheter.

MATERIALS AND METHODS

The study was conducted in transgenic pigs (Oncopigs) with induced liver tumors. Tumors were infused intra-arterially with fluorescently labeled GM. PEDD with a specialized infusion device (TriNav; TriSalus Life Sciences, Westminster, Colorado) was compared with conventional endhole microcatheter delivery in both lobar and selective infusions. Near-infrared imaging was used to detect GM fluorescent signal in tumors. Image analysis with a custom deep learning algorithm (Visiopharm A/S) was used to quantitate signal intensity in relation to the tumor border.

RESULTS

With lobar infusions, significant increases in GM signal intensity were observed in and around tumors after PEDD (n = 10) when compared with those after conventional delivery (n = 7), with PEDD increasing penetration into the tumor by 117% (P = .004). In selective infusions, PEDD (n = 9) increased penetration into the tumor by 39% relative to conventional delivery (n = 8, P = .032). Lobar PEDD of GMs to the tumor was statistically equivalent to conventional selective delivery (P = .497).

CONCLUSIONS

PEDD with a TriNav device significantly improved GM uptake in liver tumors relative to conventional infusion in both lobar and selective procedures. Lobar GM delivery with PEDD was equivalent to conventional selective delivery with an endhole device, suggesting that proximal PEDD infusions may enable effective delivery without selection of distal target vessels.

Transcatheter pseudo-vascular isolation for localization and concentration of a large molecule theranostic probe into a transgenic OncoPIG kidney tumor

INTRODUCTION

Great strides have been made identifying molecular and genetic changes expressed by various tumor types. These molecular and genetic changes are used as pharmacologic targets for precision treatment using large molecule (LM) proteins with high specificity. Theranostics exploits these LM biomolecules via radiochemistry, creating sensitive diagnostic and therapeutic agents. Intravenous (i.v.) LM drugs have an extended biopharmaceutical half-life thus resulting in an insufficient therapeutic index, permitting only palliative brachytherapy due to unacceptably high rates of systemic nontarget radiation doses to normal tissue. We employ tumor arteriole embolization isolating a tumor from the systemic circulation, and local intra-arterial (i.a.) infusion to improve uptake of a LM drug within a porcine renal tumor (RT).

METHODS

In an oncopig RT we assess the in vivo biodistribution of 99mTc-labeled macroaggregated albumin (MAA) a surrogate for a LM theranostics agent in the RT, kidney, liver, spleen, muscle, blood, and urine. Control animals underwent i.v. infusion and experimental group undergoing arteriography with pseudovascular isolation (PVI) followed by direct i.a. injection.

RESULTS

Injected dose per gram (%ID/g) of the LM at 1 min was 86.75 ± 3.76 and remained elevated up to 120 min (89.35 ± 5.77) with i.a. PVI, this increase was statistically significant (SS) compared to i.v. (13.38 ± 1.56 and 12.02 ± 1.05; p = 0.0003 p = 0.0006 at 1 and 120 min respectively). The circulating distribution of LM in the blood was less with i.a. vs i.v. infusion (2.28 ± 0.31 vs 25.17 ± 1.84 for i.v. p = 0.033 at 1 min). Other organs displayed a trend towards less exposure to radiation for i.a. with PVI compared to i.v. which was not SS.

CONCLUSION

PVI followed by i.a. infusion of a LM drug has the potential to significantly increase the first pass uptake within a tumor. This minimally invasive technique can be translated into clinical practice, potentially rendering monoclonal antibody based radioimmunotherapy a viable treatment for renal tumors.

Pigs as Clinically Relevant Models for Synergizing Interventional Oncology and Immunotherapy

Traditionally, rodent cancer models have driven preclinical oncology research. However, they do not fully recapitulate characteristics of human cancers, and their size poses challenges when evaluating tools in the interventional oncologists' armamentarium. Pig models, however, have been the gold standard for validating surgical procedures. Their size enables the study of image-guided interventions using human ultrasound (US), computed tomography (CT), and magnetic resonance (MR) imaging platforms. Furthermore, pigs have immunologic features that are similar to those of humans, which can potentially be leveraged for studying immunotherapy. Novel pig models of cancer are being developed, but additional research is required to better understand both the pig immune system and malignancy to enhance the potential for pig models in interventional oncology research. This review aims to address the main advantages and disadvantages of using a pig model for interventional oncology and outline the specific characteristics of pig models that make them more suitable for investigation of locoregional therapies.

Benefits and opportunities of the transgenic Oncopig cancer model

Cancer remains a leading cause of morbidity and mortality, and a paradigm shift is needed to fundamentally revisit drug development efforts. Pigs share close similarities to humans and may serve as an alternative model. Recently, a transgenic 'Oncopig' line has been generated to induce solid tumors with organ specificity, opening the potential of Oncopigs as a platform for developing novel therapeutic regimens.

Periphery of porcine hepatic lobes has the smallest length density of hepatic sinusoids and bile canaliculi: A stereological histological study with implications for liver biopsies

BACKGROUND

Porcine liver is widely used in hepatologic research as a large animal model with many anatomical and physiological similarities with humans. However, only limited information on porcine liver spatial microstructure has been published, especially regarding the hepatic sinusoids and bile canaliculi. The aim of our study was to quantify the sinusoidal and bile canalicular network in healthy male and female porcine livers and to map the variability of these structures with heterogenous distribution to improve the evaluability of liver biopsy samples.

METHODS

Livers from 12 healthy piglets (6 females and 6 neutered males) were sampled into 36 tissue samples per organ, representing six hepatic lobes and three different regions related to the hepatic vasculature (peripheral, paracaval and paraportal region). Histological sections were processed with a random orientation of the cutting plane. The endothelium and the bile canaliculi were stained using Ricinus communis agglutinin I lectin histochemistry. The length densities of hepatic sinusoids LV(sinusoids,liver), of bile canaliculi LV(bile canaliculi,liver) and volume fraction VV(sinusoids,liver) and surface density SV(sinusoids,liver) of sinusoids were estimated using stereological methods. The newly acquired morphometric data were compared with previously published data on density of porcine hepatocytes and fractions of connective tissue.

RESULTS

The peripheral region had smallest LV(sinusoids,liver), smallest LV(bile canaliculi,liver) and greatest VV(sinusoids,liver). The six hepatic lobes had statistically comparable length densities of both sinusoids and bile canaliculi, but the left lateral lobe had smallest VV(sinusoids,liver). Regions with greater LV(sinusoids,liver) had also greater LV(bile canaliculi,liver) and SV(sinusoids,liver) and were accompanied by greater density of smaller hepatocytes. Regions with smaller LV(sinusoids,liver) and LV(bile canaliculi,liver) contained a greater fraction of interlobular connective tissue.

CONCLUSIONS

The length density of hepatic sinusoids is smaller in the peripheral regions of the porcine liver than in other regions related to the hepatic vasculature - paracaval and paraportal regions, and smaller in castrated males than in females. Greater length density of liver sinusoids was linked with greater local density of bile canaliculi, with local increase in the density of smaller hepatocytes and, simultaneously, with smaller fractions of hepatic connective tissue. The intrahepatic and inter-sexual variability of the porcine liver morphology needs to be taken into account when designing and interpreting experiments involving the histological quantification of the microvascular network. The complete primary morphometric data describing the distribution of morphometric parameters within porcine liver were made available in a form facilitating the power analysis to justify the minimal number of tissue samples or animals required when designing further histological evaluation studies. The macroscopic map of microvessels and bile canaliculi variability facilitates their assessment in liver biopsies in the pig.

Induction and preliminary characterization of neoplastic pulmonary nodules in a transgenic pig model

OBJECTIVES

Lung cancer models in large animals are lacking. Oncopigs are transgenic pigs that carry both KRASG12D and TP53R167H Cre-inducible mutations. This study aimed to develop and histologically characterize a swine model of lung cancer that could serve for preclinical studies evaluating locoregional therapies.

MATERIALS AND METHODS

In two Oncopigs, an adenoviral vector encoding the Cre-recombinase gene (AdCre) was injected endovascularly through the pulmonary arteries or inferior vena cava. In two other Oncopigs, a lung biopsy was performed and incubated with AdCre, before reinjecting the mixture into the lungs percutaneously. Animals were clinically and biologically (complete blood count, liver enzymes and lipasemia) monitored. Obtained tumors were characterized on computed tomography (CT) and on pathology and immunohistochemistry (IHC).

RESULTS

Neoplastic lung nodules developed following 1 (1/10, 10%) endovascular inoculation, and 2 (2/6, 33%) percutaneous inoculations. All lung tumors were visible at the 1-week CT, and appeared as well-circumscribed solid nodules, with a median longest diameter of 14 mm (range: 5-27 mm). Only one complication occurred: an extravasation of the mixture into the thoracic wall during a percutaneous injection that resulted in a thoracic wall tumor. Pigs remained clinically healthy during the entire follow-up (14-21 days). On histology, tumors consisted of inflammatory undifferentiated neoplasms composed of atypical spindle and epithelioid cells and/or a fibrovascular stroma and abundant mixed leukocytic infiltrate. On IHC, atypical cells diffusely displayed expression of vimentin and some showed expression of CK WSS and CK 8/18. The tumor microenvironment contained abundant IBA1 + macrophages and giant cells, CD3 + T cells, and CD31 + blood vessels.

CONCLUSION

Tumors induced in the lungs of Oncopigs are fast growing poorly differentiated neoplasms associated with a marked inflammatory reaction that can be easily and safely induced at site specific locations. This large animal model might be suitable for interventional and surgical therapies of lung cancer.

Elevated circulating Hsp70 levels are correlative for malignancies in different mammalian species

Circulating Hsp70 levels were determined in feline and porcine cohorts using two different ELISA systems. These comparative animal models of larger organisms often reflect diseases, and especially malignant tumors, better than conventional rodent models. It is therefore essential to investigate the biology and utility of tumor biomarkers in animals such as cats and pigs. In this study, levels of free Hsp70 in the blood of cats with spontaneously occurring tumors were detected using a commercial Hsp70 ELISA (R&D Systems). Sub-analysis of different tumor groups revealed that animals with tumors of epithelial origin presented with significantly elevated circulating Hsp70 concentrations. In addition to free Hsp70 levels measured with the R&D Systems Hsp70 ELISA, levels of exosomal Hsp70 were determined using the compHsp70 ELISA in pigs. Both ELISA systems detected significantly elevated Hsp70 levels (R&D Systems: median 24.9 ng/mL; compHsp70: median 44.2 ng/mL) in the blood of a cohort of APC1311/+ pigs diagnosed with high-grade adenoma polyps, and the R&D Systems Hsp70 ELISA detected also elevated Hsp70 levels in animals with low-grade polyps. In contrast, in flTP53R167H pigs, suffering from malignant osteosarcoma, the compHsp70 ELISA (median 674.32 ng/mL), but not the R&D Systems Hsp70 ELISA (median 4.78 ng/mL), determined significantly elevated Hsp70 concentrations, indicating that in tumor-bearing animals, the dominant form of Hsp70 is of exosomal origin. Our data suggest that both ELISA systems are suitable for detecting free circulating Hsp70 levels in pigs with high-grade adenoma, but only the compHsp70 ELISA can measure elevated, tumor-derived exosomal Hsp70 levels in tumor-bearing animals.

The Oncopig as an Emerging Model to Investigate Copper Regulation in Cancer

Emerging evidence points to several fundamental contributions that copper (Cu) has to promote the development of human pathologies such as cancer. These recent and increasing identification of the roles of Cu in cancer biology highlights a promising field in the development of novel strategies against cancer. Cu and its network of regulatory proteins are involved in many different contextual aspects of cancer from driving cell signaling, modulating cell cycle progression, establishing the epithelial-mesenchymal transition, and promoting tumor growth and metastasis. Human cancer research in general requires refined models to bridge the gap between basic science research and meaningful clinical trials. Classic studies in cultured cancer cell lines and animal models such as mice and rats often present caveats when extended to humans due to inherent genetic and physiological differences. However, larger animal models such as pigs are emerging as more appropriate tools for translational research as they present more similarities with humans in terms of genetics, anatomical structures, organ sizes, and pathological manifestations of diseases like cancer. These similarities make porcine models well-suited for addressing long standing questions in cancer biology as well as in the arena of novel drug and therapeutic development against human cancers. With the emergent roles of Cu in human health and pathology, the pig presents an emerging and valuable model to further investigate the contributions of this metal to human cancers. The Oncopig Cancer Model is a transgenic swine model that recapitulates human cancer through development of site and cell specific tumors. In this review, we briefly outline the relationship between Cu and cancer, and how the novel Oncopig Cancer Model may be used to provide a better understanding of the mechanisms and causal relationships between Cu and molecular targets involved in cancer.

Animal Models of Hepatocellular Carcinoma for Local-Regional Intraarterial Therapies

Animal models play a crucial role in developing and testing new therapies for hepatocellular carcinoma (HCC), providing preclinical evidence prior to exploring human safety and efficacy outcomes. The interventional radiologist must weigh the advantages and disadvantages of various animal models available when testing a new local-regional therapy. This review highlights the currently available animal models for testing local-regional therapies for HCC and details the importance of considering animal genetics, tumor biology, and molecular mechanisms when ultimately choosing an animal model. Keywords: Animal Studies, Interventional-Vascular, Molecular Imaging-Clinical Translation, Molecular Imaging-Cancer, Chemoembolization, Liver © RSNA, 2022.

Effect of CRISPR Knockout of AXIN1 or ARID1A on Proliferation and Migration of Porcine Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is an aggressive disease lacking effective treatment. Animal models of HCC are necessary for preclinical evaluation of the safety and efficacy of novel therapeutics. Large animal models of HCC allow testing image-guided locoregional therapies, which are widely used in the management of HCC. Models with precise tumor mutations mimicking human HCC provide valuable tools for testing precision medicine. AXIN1 and ARID1A are two of the most frequently mutated genes in human HCC. Here, we investigated the effects of knockout of AXIN1 and/or ARID1A on proliferation, migration, and chemotherapeutic susceptibility of porcine HCC cells and we developed subcutaneous tumors harboring these mutations in pigs. Gene knockout was achieved by CRISPR/Cas9 and was validated by Next Generation Sequencing. AXIN1 knockout increased the migration of porcine HCC cells but did not alter the cell proliferation. Knockout of ARID1A increased both the proliferation and migration of porcine HCC cells. Simultaneous knockout of AXIN1 and ARID1A increased the migration, but did not alter the proliferation of porcine HCC cells. The effect of gene knockout on the response of porcine HCC cells to two of the most commonly used systemic and locoregional HCC treatments was investigated; sorafenib and doxorubicin, respectively. Knockout of AXIN1 and/or ARID1A did not alter the susceptibility of porcine HCC cells to sorafenib or doxorubicin. Autologous injection of CRISPR edited HCC cells resulted in development of subcutaneous tumors in pigs, which harbored the anticipated edits in AXIN1 and/or ARID1A. This study elucidates the effects of CRISPR-mediated knockout of HCC-associated genes in porcine HCC cells, and lays the foundation for development and utilization of genetically-tailored porcine HCC models for in vivo testing of novel therapeutic approaches in a clinically-relevant large animal model.

To Systematically Evaluate and Analyze the Efficacy and Safety of Transcatheter Arterial Chemoembolization (TACE) in the Treatment of Primary Liver Cancer

The efficacy and safety of transcatheter arterial chemoembolization (TACE) are systematically evaluated in the treatment of primary liver cancer, which provides a reference for clinical practice and more in-depth research. Cochrane Library, PubMed, EMbase, CBM, CNKI, VIP, and WanFang Data, supplemented by other searches, collected all randomized controlled trials (RCT) comparing TACE combined with TACE alone for HCC. The meta-analysis, after selecting the literature, extracting data, and evaluating the methodological quality of the included studies following the inclusion criteria, was performed using RevMan 5.1 software. There was statistical difference in 3-year survival rate of TACE combined with heat treatment for advanced hepatocellular carcinoma (OR = 1.72,95%CI (1.22,2.41), P=0.002, I2 = 0%, and Z = 3.12), total effective rate (OR = 1.91,95%CI (1.31,2.78), P=0.0008, I2 = 0%, and Z = 3.37), quality-of-life improvement rate (OR = 2.29,95%CI (1.62,3.23), P < 0.00001, I2 = 83%, and Z = 3.37), and complication rate (OR = 2.29,95%CI (1.62,3.23), P < 0.00001, I2 = 83%, and Z = 3.37). Compared with TACE alone, TACE combined with hyperthermia can significantly improve the survival rate and recent efficacy of patients, improve the quality of life, and have a trend to reduce the incidence of toxicity. However, its long-term efficacy and more comprehensive safety need to be verified by more sample and high-quality RCT.

Woodchuck Hepatic Anatomy and Vascular Alterations Due to Hepatocellular Carcinoma with Angiographic Atlas of the Abdomen and Pelvis

PURPOSE

To characterize the hepatic and abdominal angiographic anatomy of woodchucks and vascular changes associated with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Twenty-nine woodchucks (23 with viral-associated HCC, 6 without) underwent multiphasic computed tomography (CT). Fourteen woodchucks (8 with HCC) also underwent diagnostic angiography. Hepatic arterial diameters were measured on the CT scans. Woodchucks were divided into 3 groups: non-tumor-bearing, largest tumor supplied by the right hepatic artery (RHA), and largest tumor supplied by the left hepatic artery (LHA). Statistical analysis with a repeated measures model was performed to determine the effects of tumor location (right, left), vessel measured (RHA, LHA), and interaction between the 2 on vessel diameter. Lobar arteries supplying HCC were compared with those that did not.

RESULTS

CT anatomy and normal and variant vascular anatomy were defined. In woodchucks with HCC, LHA and RHA supplying tumors had mean diameters of 2.0 mm ± 0.3 and 1.6 mm ± 0.3 versus 1.5 mm ± 0.3 and 1.1 mm ± 0.2 for non-tumor-supplying arteries (P = .0002 and P < .0001), respectively. Lobar arteries supplying tumors were similarly ectatic. The right lateral lobe artery had the most profound increase in the mean diameter when supplying tumors, measuring 1.7 mm ± 0.1 versus 1.0 mm ± 0.1 in the non-tumor-supplying artery (P < .0001). There were no differences in the diameters of the aorta and celiac, common, and proper hepatic arteries between tumor- and non-tumor-bearing woodchucks. An angiographic atlas of the abdominal vessels was generated.

CONCLUSIONS

HCC tumoral vasculature in woodchucks was ectatic compared with normal vasculature. This phenomenon recapitulates human HCC and may facilitate investigation of transcatheter and drug delivery therapies in an HCC animal model.

Swine models for translational oncological research: an evolving landscape and regulatory considerations

Swine biomedical models have been gaining in popularity over the last decade, particularly for applications in oncology research. Swine models for cancer research include pigs that have severe combined immunodeficiency for xenotransplantation studies, genetically modified swine models which are capable of developing tumors in vivo, as well as normal immunocompetent pigs. In recent years, there has been a low success rate for the approval of new oncological therapeutics in clinical trials. The two leading reasons for these failures are either due to toxicity and safety issues or lack of efficacy. As all therapeutics must be tested within animal models prior to clinical testing, there are opportunities to expand the ability to assess efficacy and toxicity profiles within the preclinical testing phases of new therapeutics. Most preclinical in vivo testing is performed in mice, canines, and non-human primates. However, swine models are an alternative large animal model for cancer research with similarity to human size, genetics, and physiology. Additionally, tumorigenesis pathways are similar between human and pigs in that similar driver mutations are required for transformation. Due to their larger size, the development of orthotopic tumors is easier than in smaller rodent models; additionally, porcine models can be harnessed for testing of new interventional devices and radiological/surgical approaches as well. Taken together, swine are a feasible option for preclinical therapeutic and device testing. The goals of this resource are to provide a broad overview on regulatory processes required for new therapeutics and devices for use in the clinic, cross-species differences in oncological therapeutic responses, as well as to provide an overview of swine oncology models that have been developed that could be used for preclinical testing to fulfill regulatory requirements.

Cooling Effects Occur in Hepatic Microwave Ablation At Low Vascular Flow Rates and in Close Proximity to Liver Vessels - Ex Vivo

Background. The impact of vascular cooling effects in hepatic microwave ablation (MWA) is controversially discussed. The objective of this study was a systematic assessment of vascular cooling effects in hepatic MWA ex vivo. Methods. Microwave ablations were performed in fresh porcine liver ex vivo with a temperature-controlled MWA generator (902-928 MHz) and a non-cooled 14-G-antenna. Energy input was set to 9.0 kJ. Hepatic vessels were simulated by glass tubes. Three different vessel diameters (3.0, 5.0, 8.0 mm) and vessel to antenna distances (5, 10, 20 mm) were examined. Vessels were perfused with saline solution at nine different flow rates (0-500 mL/min). Vascular cooling effects were assessed at the largest cross-sectional ablation area. A quantitative and semi-quantitative/morphologic analysis was carried out. Results. 228 ablations were performed. Vascular cooling effects were observed at close (5 mm) and medium (10 mm) antenna to vessel distances (P < .05). Vascular cooling effects occurred around vessels with flow rates ≥1.0 mL/min (P < .05) and a vessel diameter ≥3 mm (P < .05). Higher flow rates did not result in more distinct cooling effects (P > .05). No cooling effects were measured at large (20 mm) antenna to vessel distances (P > .05). Conclusion. Vascular cooling effects occur in hepatic MWA and should be considered in treatment planning. The vascular cooling effect was mainly affected by antenna to vessel distance. Vessel diameter and vascular flow rate played a minor role in vascular cooling effects.