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1.  Second-generation direct-acting-antiviral hepatitis C virus treatment: Efficacy, safety, and predictors of SVR12 
World Journal of Gastroenterology  2016;22(35):8050-8059.
To gather data on the antiviral efficacy and safety of second generation direct acting antiviral (DAA) treatment with respect to sustained virological response (SVR) 12 wk after conclusion of treatment, and to determine predictors of SVR12 in this setting.
Two hundred and sixty patients treated with SOF combination partners PR (n = 51), R (n = 10), SMV (n = 30), DCV (n = 81), LDV (n = 73), or 3D (n = 15). 144/260 were pre-treated, 89/260 had liver cirrhosis, 56/260 had portal hypertension with platelets < 100/nL, 25/260 had a MELD score ≥ 10 and 17/260 were post-liver transplantation patients. 194/260 had HCV GT1, 44/260 HCV GT3.
Two hundred and forty/256 (93.7%) patients achieved SVR12 (mITT); 4/260 were lost to follow-up. SVR12 rates for subgroups were: 92% for SOF/DCV, 93% for each SOF/SMV, SOF/PR, 94% for SOF/LDV, 100% for 3D, 94% for pretreated, 87% for liver cirrhosis, 82% for patients with platelets < 100/nL, 88% post-liver transplantation, 95% for GT1a, 93% for GT1b, 90% for GT3, 100% for GT2, 4, and 6. 12 patients suffered from relapse, 6 prematurely discontinued treatment, of which 4 died. Negative predictors of SVR12 were a platelet count < 100/nL, MELD score ≥ 10 (P < 0.0001), liver cirrhosis (P = 0.005) at baseline. In Interferon-free treatment GT3 had significantly lower SVR rates than GT1 (P = 0.016). Side effects were mild.
Excellent SVR12 rates and the favorable side-effect profile of DAA-combination therapy can be well translated into “real-world”. Patients with advanced liver disease, signs of portal hypertension, especially with platelets < 100/nL and patients with GT3 are in special need for further research efforts to overcome comparatively higher rates of virological failure.
PMCID: PMC5028818  PMID: 27672299
Sofosbuvir; Simeprevir; Ledipasvir; Hepatitis C; Liver transplant; Sustained virological response; Liver cirrhosis; Side effects; Resistance; Daclatasvir
2.  Nutritional immunology: function of natural killer cells and their modulation by resveratrol for cancer prevention and treatment 
Nutrition Journal  2016;15:47.
Natural killer (NK) cells as part of the innate immune system represent the first line of defence against (virus-) infected and malignantly transformed cells. The emerging field of nutritional immunology focuses on compounds featuring immune-modulating activities in particular on NK cells, which e.g. can be exploited for cancer prevention and treatment. The plant-based nutrition resveratrol is a ternary hydroxylated stilbene, which is present in many foods and beverages, respectively. In humans it comprises a large variety of distinct biological activities. Interestingly, resveratrol strongly modulates the immune response including the activity of NK cells. This review will give an overview on NK cell functions and summarize the resveratrol-mediated modulation thereof.
PMCID: PMC4855330  PMID: 27142426
Nutritional immunology; Resveratrol; Immune modulation; NK cell activity; Innate immune system
3.  Chemovirotherapy: combining chemotherapeutic treatment with oncolytic virotherapy 
Oncolytic Virotherapy  2015;4:39-48.
Oncolytic virotherapy has made significant progress in recent years, however, widespread approval of virotherapeutics is still limited. Primarily, this is due to the fact that currently available virotherapeutics are mostly tested in monotherapeutic clinical trials exclusively (ie, not in combination with other therapies) and so far have achieved only small and often clinically insignificant responses. Given that the predominantly immunotherapeutic mechanism of virotherapeutics is somewhat time-dependent and rapidly growing tumors therefore exhibit only minor chances of being captured in time, scenarios with combination partners are postulated to be more effective. Combinatory settings would help to achieve a rapid stabilization or even reduction of onset tumor masses while providing enough time (numerous months) for achieving immuno(viro)therapeutic success. For this reason, combination strategies of virotherapy with highly genotoxic regimens, such as chemotherapy, are of major interest. A number of clinical trials bringing the concepts of chemotherapy and virotherapy together have previously been undertaken, but optimal scheduling of chemovirotherapy (maximizing the anti-tumor effect while minimizing the risk of overlapping toxicity) still constitutes a major challenge. Therefore, an overview of published as well as ongoing Phase I–III trials should improve our understanding of current challenges and future developments in this field.
PMCID: PMC4918378  PMID: 27512669
cancer; combination therapy; chemotherapy; virotherapy; oncolytic virus; clinical trials
4.  Liver-directed gene expression employing synthetic transcriptional control units 
World Journal of Gastroenterology  2005;11(34):5295-5302.
AIM: To generate and characterize the synthetic transcriptional control units for transcriptional targeting of the liver, thereby compensating for the lack of specificity of currently available gene therapeutic vector systems.
METHODS: Synthetic transcriptional control unit constructs were generated and analyzed for transcriptional activities in different cell types by FACS quantification, semi-quantitative RT-PCR, and Western blotting.
RESULTS: A new bifunctionally-enhanced green fluorescent protein (EGFP)/neor fusion gene cassette was generated, and could flexibly be used both for transcript quantification and for selection of stable cell clones. Then, numerous synthetic transcriptional control units consisting of a minimal promoter linked to “naturally” derived composite enhancer elements from liver-specific expressed genes or binding sites of liver-specific transcription factors were inserted upstream of this reporter cassette. Following liposome-mediated transfection, EGFP reporter protein quantification by FACS analysis identified constructs encoding multimerized composite elements of the apolipoprotein B100 (ApoB) promoter or the ornithin transcarbamoylase (OTC) enhancer to exhibit maximum transcriptional activities in liver originating cell lines, but only background levels in non-liver originating cell lines. In contrast, constructs encoding only singular binding sites of liver-specific transcription factors, namely hepatocyte nuclear factor (HNF)1, HNF3, HNF4, HNF5, or CAAT/enhancer binding protein (C/EBP) only achieved background levels of EGFP expression. Finally, both semi-quantitative RT-PCR and Western blotting analysis of Hep3B cells demonstrated maximum transcriptional activities for a multimeric 4xApoB cassette construct, which fully complied with the data obtained by initial FACS analysis.
CONCLUSION: Synthetic transcriptional control unit constructs not only exhibit a superb degree of structural compactness, but also provide new means for liver-directed expression of therapeutic genes.
PMCID: PMC4622798  PMID: 16149135
Liver gene therapy; Hepatoma gene therapy; Liver-directed gene expression; Synthetic liver-specific promoters
5.  A Novel Armed Oncolytic Measles Vaccine Virus for the Treatment of Cholangiocarcinoma 
Human Gene Therapy  2013;24(5):554-564.
Cholangiocarcinoma (CC) is curable only in early stages by complete surgical resection. Thus, in advanced disease stages in which a complete removal of the tumor mass is no longer possible and palliative chemotherapy achieves only modest success, therapeutics employing new methods of action are desperately needed. Oncolytic viruses employed in clinical studies have been shown to spread preferentially in cancer cells. Beyond that, virotherapeutic cell killing can be enhanced by virus-based expression of suicide genes. We engineered a measles vaccine virus (MeV) vector expressing super cytosine deaminase (SCD), a fusion protein of yeast cytosine deaminase and uracil phosphoribosyltransferase, which converts the prodrug 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU) and subsequently to 5-fluorouridine-monophosphate. This novel vector was evaluated using three different human-derived CC cell lines. In vitro, all CC cell lines were found to be permissive to MeV infection. Partial blocking of MeV-mediated oncolysis could be overcome by employment of the SCD transgene together with administration of 5-FC. In vivo, intratumoral application of SCD-armed MeV together with a systemic 5-FC treatment showed a significant reduction in tumor size in a TFK-1 xenograft mouse model when compared with virus-only treatment. In a second animal experiment employing a HuCCT1 xenograft tumor model, an enhanced SCD-armed MeV vector, in which the SCD transgene was expressed from a different genomic position, led not only to reduced tumor volumes, but also to a significant survival benefit. On the basis of these encouraging preclinical data on employment of SCD-armed MeV for the virotherapeutic treatment of chemotherapy-resistant CC, a clinical virotherapy trial is set up currently.
Lange and colleagues engineer a measles vaccine virus (MeV) vector expressing an enzyme that converts 5-fluorocytosine (5-FC) prodrug into 5-fluorouracil-monophosphate. Partial blocking of MeV-mediated oncolysis could be overcome by vector and 5–FC co-administration in cell lines. In vivo, intratumoral vector injection along with systemic 5–FC treatment resulted in significant tumor reduction in a xenograft mouse model.
PMCID: PMC3655633  PMID: 23550539
6.  Innate Immune Defense Defines Susceptibility of Sarcoma Cells to Measles Vaccine Virus-Based Oncolysis 
Journal of Virology  2013;87(6):3484-3501.
The oncolytic potential of measles vaccine virus (MeV) has been demonstrated in several tumor entities. Here, we investigated the susceptibility of eight sarcoma cell lines to MeV-mediated oncolysis and found five to be susceptible, whereas three proved to be resistant. In the MeV-resistant cell lines, we often observed an inhibition of viral replication along with a strong upregulation of the intracellular virus-sensing molecule RIG-I and of the interferon (IFN)-stimulated gene IFIT1. Not only expression of IFIT1 but also phosphorylation of IFN-stimulated Stat1 took place rapidly and were found to be persistent over time. In contrast, susceptible cell lines showed a much weaker, delayed, or completely missing expression of IFIT1 as well as a delayed or only transient phosphorylation of Stat1, whereas exogenic stimulation with beta interferon (IFN-β) resulted in a comparable profound activation of Stat1 and expression of IFIT1 in all cell lines. Pretreatment with IFN-β rendered three of the susceptible cell lines more resistant to MeV-mediated oncolysis. These data suggest that differences in the innate immune defense often account for different degrees of susceptibility of sarcoma cell lines to MeV-mediated oncolysis. From a therapeutic perspective, we were able to overcome resistance to MeV by increasing the multiplicity of infection (MOI) and by addition of the prodrug 5-fluorocytosine (FC), thereby exploiting the suicide gene function of virotherapeutic vector MeV-SCD armed with the SCD fusion protein, which consists of yeast cytosine deaminase and yeast uracil phosphoribosyltransferase.
PMCID: PMC3592150  PMID: 23302892
7.  Assessment of current virotherapeutic application schemes: “hit hard and early” versus “killing softly”? 
Over the past two decades, a considerable amount of oncolytic vector families has entered numerous clinical trials. However, to this date, the field has not yet been able to come to a common understanding regarding the best possible ways to administer oncolytic viruses to cancer patients. This is mainly due to the fact that so far clinical trials being designed for head-to-head comparisons (such as using two different virotherapeutics originating from two distinct virus families being applied via identical routes in the same types of cancer) are still missing. Hence, there is no consent (i) on the best route of virotherapeutics administration (e.g., systemic versus intratumoral), (ii) on the virus dosages to be applied, (iii) on dosing intervals, and (iv) on the numbers of repetitive courses of virus administration. As the detailed comparison of clinical virotherapy trial regimens is time-consuming and complex, we here present an overview of current state-of-the-art virotherapeutic application schemes. Notably, our comprehensive assessment culminates in raising two rough classifications of virotherapeutic strategies, i.e., “hit hard and early” versus “killing softly”. In order to find out which one of these two gross alternatives might be most successful for each and every tumor entity, we here suggest the implementation of phase 1/2 studies, which primarily aim at a repetitive sampling and analysis of tumor samples in cancer patients treated with oncolytic viruses reading out (i) virus-specific, (ii) tumor-specific as well as (iii) immunotherapeutic parameters. On this basis, a rational design of significantly improved virotherapeutic application schemes should be possible in the future.
PMCID: PMC4782955  PMID: 27119110
8.  Combination of the oral histone deacetylase inhibitor resminostat with oncolytic measles vaccine virus as a new option for epi-virotherapeutic treatment of hepatocellular carcinoma 
Epigenetic therapies such as histone deacetylase inhibitors (HDACi) not only have the capability to decrease tumor cell proliferation and to induce tumor cell death but also to silence antiviral response genes. Here, we investigated whether the combination of an oncolytic measles vaccine virus (MeV) with the novel oral HDACi resminostat (Res), being in clinical testing in patients with hepatocellular carcinoma (HCC), results in an enhanced efficacy of this epi-virotherapeutic approach compared to any of the two corresponding monotherapies. When testing a panel of human hepatoma cell lines, we found (i) a significantly improved rate of primary infections when using oncolytic MeV under concurrent treatment with resminostat, (ii) a boosted cytotoxic effect of the epi-virotherapeutic combination (Res + MeV) with enhanced induction of apoptosis, and, quite importantly, (iii) an absence of any resminostat-induced impairment of MeV replication and spread. Beyond that, we could also show that (iv) resminostat, after hepatoma cell stimulation with exogenous human interferon (IFN)-β, is able to prevent the induction of IFN-stimulated genes, such as IFIT-1. This finding outlines the possible impact of resminostat on cellular innate immunity, being instrumental in overcoming resistances to MeV-mediated viral oncolysis. Thus, our results support the onset of epi-virotherapeutic clinical trials in patients exhibiting advanced stages of HCC.
PMCID: PMC4782956  PMID: 27119111
9.  Oncolytic Viruses 
Advances in Virology  2012;2012:320206.
PMCID: PMC3384932  PMID: 22754567
10.  Epigenetic activities of flavonoids in the prevention and treatment of cancer 
Clinical Epigenetics  2015;7(1):64.
Aberrant epigenetic modifications are described in an increasing number of pathological conditions, including neurodegenerative diseases, cardiovascular diseases, diabetes mellitus type 2, obesity and cancer. The general reversibility of epigenetic changes makes them an attractive and promising target e.g. in the treatment of cancer. Thus, a growing number of epigenetically active compounds are currently tested in clinical trials for their therapeutic potential. Interestingly, many phytochemicals present in plant foods, particularly flavonoids, are suggested to be able to alter epigenetic cellular mechanisms. Flavonoids are natural phenol compounds that form a large group of secondary plant metabolites with interesting biological activities. They can be categorized into six major subclasses, which display diverse properties affecting the two best characterized epigenetic mechanisms: modulation of the DNA methylation status and histone acetylation. High dietary flavonoid intake has strongly been suggested to reduce the risk of numerous cancer entities in a large body of epidemiological studies. Established health-promoting effects of diets rich in fruit and vegetables are faced by efforts to use purified flavonoids as supplements or pharmaceuticals, whereupon data on the latter applications remain controversial. The purpose of this review is to give an overview of current research on flavonoids to further elucidate their potential in cancer prevention and therapy, thereby focusing on their distinct epigenetic activities.
PMCID: PMC4497414  PMID: 26161152
Epigenetics; HDAC; DNMT; Flavonoids; Phytochemicals; Nutrition; Cancer
11.  First-generation protease inhibitor-triple therapy: SVR 24, safety, and predictors of response in a large single center cohort 
Virology Journal  2015;12:37.
Aim of this retrospective study was to analyze the efficacy, safety, and predictors of treatment success for first-generation-PI triple therapies, including either boceprevir or telaprevir, in a mono-centric “real-life” setting with respect to SVR 24.
131 patients (102 patients telaprevir, 29 patients boceprevir) were treated. Of these, 33/131 patients were treatment naïve, 72/131 patients had been pretreated with PEG-IFN/RBV (PR) (thereof: 36 with non-response, 30 with relapse, 6 unknown), and 26/131 patients previously had received non-pegylated interferon. 96/131 patients were infected with HCV genotype 1b. 41/131 patients had liver cirrhosis.
95/131 (73%) patients achieved SVR 24. SVR rates for subgroups were: 26/33 (79%) for treatment naïve, 25/30 (83%) for PR-relapse, 20/36 (56%) for PR-non-response, 21/26 (81%) for non-PR pretreated patients, (26/41) 63% for patients with liver cirrhosis, 23/35 (66%) genotype 1a, 72/96 (75%) genotype 1b. Predictors of SVR 24 were eRVR and a negative viral load at PI-treatment week 4 (p < 0.0001), negative predictors were quantifiable HCV viral load at PI-treatment week 4 (p < 0.0001), baseline platelet count < 100/nl (p < 0.0001), and previous PR-non-response (p = 0.006). 33/131 (25%) patients discontinued treatment prematurely, of those 14/131 (11%) patients due to virological failure. Side effects were frequent (anemia 59/131 [45%], severe infections 6/131 [5%]).
According to our SVR 24 results, efficacy of PI-based triple therapy in our “real-life” cohort is comparable to the large multi-centric clinical trials. Pronounced side effects are frequent during therapy and often need complex therapeutic interventions. Since new DAA are available, it is open to discussion, if first-generation PI-triple therapy is no longer indicated at all.
PMCID: PMC4355422  PMID: 25889921
Telaprevir; Boceprevir; Hepatitis C; Sustained virological response; Liver cirrhosis; Side effects
12.  Bifunctional chimeric SuperCD suicide gene -YCD: YUPRT fusion is highly effective in a rat hepatoma model 
World Journal of Gastroenterology  2005;11(44):6910-6919.
AIM: To investigate the effects of catalytically superior gene-directed enzyme prodrug therapy systems on a rat hepatoma model.
METHODS: To increase hepatoma cell chemosensitivity for the prodrug 5-fluorocytosine (5-FC), we generated a chimeric bifunctional SuperCD suicide gene, a fusion of the yeast cytosine deaminase (YCD) and the yeast uracil phosphoribosyltransferase (YUPRT) gene.
RESULTS: In vitro stably transduced Morris rat hepatoma cells (MH) expressing the bifunctional SuperCD suicide gene (MH SuperCD) showed a clearly marked enhancement in cell killing when incubated with 5-FC as compared with MH cells stably expressing YCD solely (MH YCD) or the cytosine deaminase gene of bacterial origin (MH BCD), respectively. In vivo, MH SuperCD tumors implanted both subcutaneously as well as orthotopically into the livers of syngeneic ACI rats demonstrated significant tumor regressions (P<0.01) under both high dose as well as low dose systemic 5-FC application, whereas MH tumors without transgene expression (MH naïve) showed rapid progression. For the first time, an order of in vivo suicide gene effectiveness (SuperCD>>YCD>>BCD>>>negative control) was defined as a result of a direct in vivo comparison of all three suicide genes.
CONCLUSION: Bifunctional SuperCD suicide gene expression is highly effective in a rat hepatoma model, thereby significantly improving both the therapeutic index and the efficacy of hepatocellular carcinoma killing by fluorocytosine.
PMCID: PMC4717030  PMID: 16437592
YCD/YUPRT fusion; Cytosine deaminase; GDEPT; Suicide gene therapy; Hepatoma therapy
13.  Attenuated and Protease-Profile Modified Sendai Virus Vectors as a New Tool for Virotherapy of Solid Tumors 
PLoS ONE  2014;9(3):e90508.
Multiple types of oncolytic viruses are currently under investigation in clinical trials. To optimize therapeutic outcomes it is believed that the plethora of different tumor types will require a diversity of different virus types. Sendai virus (SeV), a murine parainfluenza virus, displays a broad host range, enters cells within minutes and already has been applied safely as a gene transfer vector in gene therapy patients. However, SeV spreading naturally is abrogated in human cells due to a lack of virus activating proteases. To enable oncolytic applications of SeV we here engineered a set of novel recombinant vectors by a two-step approach: (i) introduction of an ubiquitously recognized cleavage-motive into SeV fusion protein now enabling continuous spreading in human tissues, and (ii) profound attenuation of these rSeV by the knockout of viral immune modulating accessory proteins. When employing human hepatoma cell lines, newly generated SeV variants now reached high titers and induced a profound tumor cell lysis. In contrast, virus release from untransformed human fibroblasts or primary human hepatocytes was found to be reduced by about three log steps in a time course experiment which enables the cumulation of kinetic differences of the distinct phases of viral replication such as primary target cell infection, target cell replication, and progeny virus particle release. In a hepatoma xenograft animal model we found a tumor-specific spreading of our novel recombinant SeV vectors without evidence of biodistribution into non-malignant tissues. In conclusion, we successfully developed novel tumor-selective oncolytic rSeV vectors, constituting a new tool for virotherapy of solid tumors being ready for further preclinical and clinical development to address distinct tumor types.
PMCID: PMC3944018  PMID: 24598703
14.  Epigenetic Impacts of Ascorbate on Human Metastatic Melanoma Cells 
Frontiers in Oncology  2014;4:227.
In recent years, increasing evidence has emerged demonstrating that high-dose ascorbate bears cytotoxic effects on cancer cells in vitro and in vivo, making ascorbate a pro-oxidative drug that catalyzes hydrogen peroxide production in tissues instead of acting as a radical scavenger. This anticancer effect of ascorbate is hypoxia-inducible factor-1α- and O2-dependent. However, whether the intracellular mechanisms governing this effect are modulated by epigenetic phenomena remains unknown. We treated human melanoma cells with physiological (200 μM) or pharmacological (8 mM) ascorbate for 1 h to record the impact on DNA methyltransferase (DNMT)-activity, histone deacetylases (HDACs), and microRNA (miRNA) expression after 12 h. The results were analyzed with the MIRUMIR online tool that estimates the power of miRNA to serve as potential biomarkers to predict survival of cancer patients. FACS cell-cycle analyses showed that 8 mM ascorbate shifted BLM melanoma cells toward the sub-G1 fraction starting at 12 h after an initial primary G2/M arrest, indicative for secondary apoptosis induction. In pharmacological doses, ascorbate inhibited the DNMT activity in nuclear extracts of MeWo and BLM melanoma cells, but did not inhibit human HDAC enzymes of classes I, II, and IV. The expression of 151 miRNAs was altered 12 h after ascorbate treatment of BLM cells in physiological or pharmacological doses. Pharmacological doses up-regulated 32 miRNAs (≥4-fold) mainly involved in tumor suppression and drug resistance in our preliminary miRNA screening array. The most prominently up-regulated miRNAs correlated with a significantly increased overall survival of breast cancer or nasopharyngeal carcinoma patients of the MIRUMIR database with high expression of the respective miRNA. Our results suggest a possible epigenetic signature of pharmacological doses of ascorbate in human melanoma cells and support further pre-clinical and possibly even clinical evaluation of ascorbate for melanoma therapy.
PMCID: PMC4142417  PMID: 25202679
ascorbate; vitamin C; cancer; melanoma; epigenetics; microRNA; HDAC; DNMT
15.  Feasibility of Telaprevir-Based Triple Therapy in Liver Transplant Patients with Hepatitis C Virus: SVR 24 Results  
PLoS ONE  2013;8(11):e80528.
Management of recurrent Hepatitis C virus (HCV) infection following liver transplantation remains a major challenge. In non-transplanted HCV genotype 1 patients, the introduction of protease inhibitor-based regimens has significantly increased the rate of sustained virological response. In this follow-up study, on the first published cohort of post-liver transplant patients treated with telaprevir-based triple therapy, we investigated both efficacy and safety data in follow-up to 24 weeks (SVR 24) after end of treatment (EOT). SVR 24 efficacy and safety data from 9 liver transplant HCV patients being treated with telaprevir, pegylated interferon, and ribavirin, showed 5 of the transplanted patients accomplished the full duration of the 48 week triple therapy.
Notable were the 4 patients found to be HCV RNA-negative at week 4, and 8 patients at week 12. Upon EOT, at week 48, 6 patients were HCV RNA-negative. Importantly, at follow-up (24 weeks after EOT), a favorable sustained virological response rate was observed in 5 of these patients with HCV RNA remaining negative, including in one patient who discontinued treatment prematurely. Due to side effects, 2 patients discontinued, 2 suffered from virological breakthrough after the telaprevir treatment phase, and 1 patient had a relapse after EOT. Two thirds of patients exhibited hematological side effects requiring ribavirin dose reductions, administration of erythropoetin, or even blood transfusions.
This retrospective analysis provides evidence that - with respect to SVR 24 - liver transplant patients suffering from HCV genotype 1 recurrence may benefit from a telaprevir-based triple therapy as this new regimen showed acceptable antiviral efficacy in this small cohort of mostly pre-treated patients. Management of drug-drug interactions is challenging, but feasible. In part severe side effects are frequent during treatment and require therapeutic interventions.
PMCID: PMC3827217  PMID: 24265827
17.  Optical Detection and Virotherapy of Live Metastatic Tumor Cells in Body Fluids with Vaccinia Strains 
PLoS ONE  2013;8(9):e71105.
Metastatic tumor cells in body fluids are important targets for treatment, and critical surrogate markers for evaluating cancer prognosis and therapeutic response. Here we report, for the first time, that live metastatic tumor cells in blood samples from mice bearing human tumor xenografts and in blood and cerebrospinal fluid samples from patients with cancer were successfully detected using a tumor cell-specific recombinant vaccinia virus (VACV). In contrast to the FDA-approved CellSearch system, VACV detects circulating tumor cells (CTCs) in a cancer biomarker-independent manner, thus, free of any bias related to the use of antibodies, and can be potentially a universal system for detection of live CTCs of any tumor type, not limited to CTCs of epithelial origin. Furthermore, we demonstrate for the first time that VACV was effective in preventing and reducing circulating tumor cells in mice bearing human tumor xenografts. Importantly, a single intra-peritoneal delivery of VACV resulted in a dramatic decline in the number of tumor cells in the ascitic fluid from a patient with gastric cancer. Taken together, these results suggest VACV to be a useful tool for quantitative detection of live tumor cells in liquid biopsies as well as a potentially effective treatment for reducing or eliminating live tumor cells in body fluids of patients with metastatic disease.
PMCID: PMC3760980  PMID: 24019862
18.  Resveratrol as a Pan-HDAC Inhibitor Alters the Acetylation Status of Jistone Proteins in Human-Derived Hepatoblastoma Cells 
PLoS ONE  2013;8(8):e73097.
The polyphenolic alcohol resveratrol has demonstrated promising activities for the prevention and treatment of cancer. Different modes of action have been described for resveratrol including the activation of sirtuins, which represent the class III histone deacetylases (HDACs). However, little is known about the activity of resveratrol on the classical HDACs of class I, II and IV, although these classes are involved in cancer development or progression and inhibitors of HDACs (HDACi) are currently under investigation as promising novel anticancer drugs. We could show by in silico docking studies that resveratrol has the chemical structure to inhibit the activity of different human HDAC enzymes. In vitro analyses of overall HDAC inhibition and a detailed HDAC profiling showed that resveratrol inhibited all eleven human HDACs of class I, II and IV in a dose-dependent manner. Transferring this molecular mechanism into cancer therapy strategies, resveratrol treatment was analyzed on solid tumor cell lines. Despite the fact that hepatocellular carcinoma (HCC) is known to be particularly resistant against conventional chemotherapeutics, treatment of HCC with established HDACi already has shown promising results. Testing of resveratrol on hepatoma cell lines HepG2, Hep3B and HuH7 revealed a dose-dependent antiproliferative effect on all cell lines. Interestingly, only for HepG2 cells a specific inhibition of HDACs and in turn a histone hyperacetylation caused by resveratrol was detected. Additional testing of human blood samples demonstrated a HDACi activity by resveratrol ex vivo. Concluding toxicity studies showed that primary human hepatocytes tolerated resveratrol, whereas in vivo chicken embryotoxicity assays demonstrated severe toxicity at high concentrations. Taken together, this novel pan-HDACi activity opens up a new perspective of resveratrol for cancer therapy alone or in combination with other chemotherapeutics. Moreover, resveratrol may serve as a lead structure for chemical optimization of bioavailability, pharmacology or HDAC inhibition.
PMCID: PMC3758278  PMID: 24023672
19.  Selective Protection of Human Liver Tissue in TNF-Targeting of Cancers of the Liver by Transient Depletion of Adenosine Triphosphate 
PLoS ONE  2012;7(12):e52496.
Tumor necrosis factor alpha (TNF) is able to kill cancer cells via receptor-mediated cell death requiring adenosine triphosphate (ATP). Clinical usage of TNF so far is largely limited by its profound hepatotoxicity. Recently, it was found in the murine system that specific protection of hepatocytes against TNF's detrimental effects can be achieved by fructose-mediated ATP depletion therein. Before employing this quite attractive selection principle in a first clinical trial, we here comprehensively investigated the interdependence between ATP depletion and TNF hepatotoxicity in both in vitro and ex vivo experiments based on usage of primary patient tissue materials.
Primary human hepatocytes, and both non-tumorous and tumorous patient-derived primary liver tissue slices were used to elucidate fructose-induced ATP depletion and TNF-induced cytotoxicity.
PHH as well as tissue slices prepared from non-malignant human liver specimen undergoing a fructose-mediated ATP depletion were both demonstrated to be protected against TNF-induced cell death. In contrast, due to tumor-specific overexpression of hexokinase II, which imposes a profound bypass on hepatocytic-specific fructose catabolism, this was not the case for human tumorous liver tissues.
Normal human liver tissues can be protected transiently against TNF-induced cell death by systemic pretreatment with fructose used in non-toxic/physiologic concentrations. Selective TNF-targeting of primary and secondary tumors of the liver by transient and specific depletion of hepatocytic ATP opens up a new clinical avenue for the TNF-based treatment of liver cancers.
PMCID: PMC3525543  PMID: 23272249
20.  Efficient Colonization and Therapy of Human Hepatocellular Carcinoma (HCC) Using the Oncolytic Vaccinia Virus Strain GLV-1h68 
PLoS ONE  2011;6(7):e22069.
Virotherapy using oncolytic vaccinia virus strains is one of the most promising new strategies for cancer therapy. In this study, we analyzed for the first time the therapeutic efficacy of the oncolytic vaccinia virus GLV-1h68 in two human hepatocellular carcinoma cell lines HuH7 and PLC/PRF/5 (PLC) in cell culture and in tumor xenograft models. By viral proliferation assays and cell survival tests, we demonstrated that GLV-1h68 efficiently colonized, replicated in, and did lyse these cancer cells in culture. Experiments with HuH7 and PLC xenografts have revealed that a single intravenous injection (i.v.) of mice with GLV-1h68 resulted in a significant reduction of primary tumor sizes compared to uninjected controls. In addition, replication of GLV-1h68 in tumor cells led to strong inflammatory and oncolytic effects resulting in intense infiltration of MHC class II-positive cells like neutrophils, macrophages, B cells and dendritic cells and in up-regulation of 13 pro-inflammatory cytokines. Furthermore, GLV-1h68 infection of PLC tumors inhibited the formation of hemorrhagic structures which occur naturally in PLC tumors. Interestingly, we found a strongly reduced vascular density in infected PLC tumors only, but not in the non-hemorrhagic HuH7 tumor model. These data demonstrate that the GLV-1h68 vaccinia virus may have an enormous potential for treatment of human hepatocellular carcinoma in man.
PMCID: PMC3133637  PMID: 21779374
21.  Improved reproducibility in preparing precision-cut liver tissue slices 
Cytotechnology  2009;61(3):145-152.
Precision-cut liver tissue slices (PCLS) have been used for decades to study pharmacological metabolism as well as toxicology and efficacy of novel substances on primary material under standardized conditions. Slicing of primary liver tissue has been done using different slicing machines. Since there has been great variability in the results, we sought to compare the reproducibility of tissue slices generated using the newly developed Leica VT1200 S vibrating blade microtome with Vibrocheck (LV) and the Krumdieck tissue slicer (KD) which has been the standard apparatus for this application so far. Liver samples from five different species (human, pig, cattle, rat, mouse) were cut and the reproducibility of slice thickness was analyzed by cross sectioning the PCLS. The quality of the sliced tissue was determined via measurement of the ATP content. As a result, we found an improved accuracy and reproducibility of rat, mouse and human tissue slices using the new Leica vibrating blade microtome.
PMCID: PMC2825296  PMID: 20091220
Primary culture; Precision-cut liver slices (PCLS); Leica VT1200 S vibrating blade microtome; Krumdieck tissue slicer
22.  Early MRI response monitoring of patients with advanced hepatocellular carcinoma under treatment with the multikinase inhibitor sorafenib 
BMC Cancer  2009;9:208.
New therapeutic principles in clinical oncology require the adjustment of response criteria to govern therapy decisions. For advanced hepatocellular carcinoma (HCC) a new era has recently begun by the approval of the multikinase inhibitor sorafenib. As a unique feature, HCC usually develops in a diseased liver and current imaging technologies employing classical response criteria have not been prospectively evaluated for this new treatment.
MRI signal patterns were assessed in 21 advanced HCC patients receiving sorafenib. MRI was performed at baseline and in short-term intervals thereafter. Signal changes under therapy on T1WI, T2WI and post-gadolinium images including necrosis volume and its ratio to the entire tumor volume were compared to baseline imaging. To assess the association between the categorical variables, Fisher's exact tests were applied for a statistical analysis. Survey time ranged from 2–65 weeks, and a total of 39 target lesions were evaluated.
Signal abnormalities during sorafenib therapy were disclosed by T1WI and T2WI in 15/21 patients. The predominant tumor signal change was hyperintensity on both T1WI and T2WI. Interestingly, most patients developed MRI signal changes within 4 weeks of therapy; in contrast, two non-responders did not show any signal alteration at follow-up. Under therapy, 16/21 patients presented with new or progressive necrosis, whereas 7 patients achieved temporarily >75% tumor necrosis under sorafenib. Significantly associated MRI variables were increase in T1WI signal and tumor necrosis (p = 0.017) as well as increase of tumor necrosis with an elevated ratio of necrotic to vital tumor areas (p = 0.002). Remarkably, some (3/13) of the patients developing necrotic tumor areas showed a relevant (>20%) increase in tumor volume, which should be considered in the assessment of imaging studies.
As sorafenib induces early intralesional necrosis with profound changes in T1WI/T2WI MRI signal intensities and measurable necrotic tumor areas in most HCC patients, early MRI-based evaluation could pave the way for its rationale and cost-effective application.
PMCID: PMC2714320  PMID: 19558720

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