NLGN4X TCR transgenic T cells to treat gliomas

BACKGROUND

Neuroligin 4 X-linked (NLGN4X) harbors a human leukocyte antigen (HLA)-A*02-restricted tumor-associated antigen, overexpressed in human gliomas, that was found to induce specific cytotoxic T cell responses following multi-peptide vaccination in patients with newly diagnosed glioblastoma.

METHODS

T cell receptor (TCR) discovery was performed using droplet-based single-cell TCR sequencing of NLGN4X-tetramer-sorted T cells postvaccination. The identified TCR was delivered to Jurkat T cells and primary human T cells (NLGN4X-TCR-T). Functional profiling of NLGN4X-TCR-T was performed by flow cytometry and cytotoxicity assays. Therapeutic efficacy of intracerebroventricular NLGN4X-TCR-T was assessed in NOD scid gamma (NSG) major histocompatibility complex (MHC) I/II knockout (KO) (NSG MHC I/II KO) mice bearing NLGN4X-expressing experimental gliomas.

RESULTS

An HLA-A*02-restricted vaccine-induced T cell receptor specifically binding NLGN4X131-139 was applied for preclinical therapeutic use. Reactivity, cytotoxicity, and polyfunctionality of this NLGN4X-specific TCR are demonstrated in various cellular models. Intracerebroventricular administration of NLGN4X-TCR-T prolongs survival and leads to an objective response rate of 44.4% in experimental glioma-bearing NSG MHC I/II KO mice compared to 0.0% in control groups.

CONCLUSION

NLGN4X-TCR-T demonstrate efficacy in a preclinical glioblastoma model. On a global scale, we provide the first evidence for the therapeutic retrieval of vaccine-induced human TCRs for the off-the-shelf treatment of glioblastoma patients.Keywords cell therapy | glioblastoma | T cell receptor | tumor antigen.

Gene Augmentation of CHM Using Non-Viral Episomal Vectors in Models of Choroideremia

Choroideremia (CHM) is an X-linked chorioretinal dystrophy leading to progressive retinal degeneration that results in blindness by late adulthood. It is caused by mutations in the CHM gene encoding the Rab Escort Protein 1 (REP1), which plays a crucial role in the prenylation of Rab proteins ensuring correct intracellular trafficking. Gene augmentation is a promising therapeutic strategy, and there are several completed and ongoing clinical trials for treating CHM using adeno-associated virus (AAV) vectors. However, late-phase trials have failed to show significant functional improvements and have raised safety concerns about inflammatory events potentially caused by the use of viruses. Therefore, alternative non-viral therapies are desirable. Episomal scaffold/matrix attachment region (S/MAR)-based plasmid vectors were generated containing the human CHM coding sequence, a GFP reporter gene, and ubiquitous promoters (pS/MAR-CHM). The vectors were assessed in two choroideremia disease model systems: (1) CHM patient-derived fibroblasts and (2) chmru848 zebrafish, using Western blotting to detect REP1 protein expression and in vitro prenylation assays to assess the rescue of prenylation function. Retinal immunohistochemistry was used to investigate vector expression and photoreceptor morphology in injected zebrafish retinas. The pS/MAR-CHM vectors generated persistent REP1 expression in CHM patient fibroblasts and showed a significant rescue of prenylation function by 75%, indicating correction of the underlying biochemical defect associated with CHM. In addition, GFP and human REP1 expression were detected in zebrafish microinjected with the pS/MAR-CHM at the one-cell stage. Injected chmru848 zebrafish showed increased survival, prenylation function, and improved retinal photoreceptor morphology. Non-viral S/MAR vectors show promise as a potential gene-augmentation strategy without the use of immunogenic viral components, which could be applicable to many inherited retinal disease genes.

Successful large gene augmentation of USH2A with non-viral episomal vectors

USH2A mutations are a common cause of autosomal recessive retinitis pigmentosa (RP) and Usher syndrome, for which there are currently no approved treatments. Gene augmentation is a valuable therapeutic strategy for treating many inherited retinal diseases; however, conventional adeno-associated virus (AAV) gene therapy cannot accommodate cDNAs exceeding 4.7 kb, such as the 15.6-kb-long USH2A coding sequence. In the present study, we adopted an alternative strategy to successfully generate scaffold/matrix attachment region (S/MAR) DNA plasmid vectors containing the full-length human USH2A coding sequence, a GFP reporter gene, and a ubiquitous promoter (CMV or CAG), reaching a size of approximately 23 kb. We assessed the vectors in transfected HEK293 cells and USH2A patient-derived dermal fibroblasts in addition to ush2au507 zebrafish microinjected with the vector at the one-cell stage. pS/MAR-USH2A vectors drove persistent transgene expression in patient fibroblasts with restoration of usherin. Twelve months of GFP expression was detected in the photoreceptor cells, with rescue of Usher 2 complex localization in the photoreceptors of ush2au507 zebrafish retinas injected with pS/MAR-USH2A. To our knowledge, this is the first reported vector that can be used to express full-length usherin with functional rescue. S/MAR DNA vectors have shown promise as a novel non-viral retinal gene therapy, warranting further translational development.

Abstract 1769: A combination approach of a cellular library and single cell microfluidics analysis for the rapid selection of CAR-T cells

Within the last decade CAR-T cells have changed the landscape of treatment regimen for leukemia and myeloma, which is reflected by the first FDA approval of this class of living drugs in 2017. As of today, the clinical trial situation aims on CAR-T applicability in solid tumors, which is more arduous due to antigen heterogeneity and limited CAR-T persistence. More personalized and multi-target oriented cellular products may offer a solution to overcome these problems but then CAR identification and selection display the major bottleneck in the drug development process. Usually, matching scFvs are selected from targeting screens of a phage-display library and hits are subsequently cloned in CAR backbones and tested for functionality and possible limiting factors as the occurrence of tonic signaling. This makes the whole process very time consuming and laborious. Within this project, we propose a novel CAR-T selection method that rapidly shortens the discovery procedure. We have developed a full length CAR library in nS/MARt DNA vectors that is electroporated in a Jurkat reporter cell line reflecting entirely its full diversity. By this, we can quickly identify the amount of tonic signaling CARs and exclude them from further selection. For on-target selection we first perform a bulk pre-selection followed by a single cell functionality screening using the Berkeley Lights Lightning™ device. This allows us to export hits as clonal viable cells that undergo long length Nanopore CAR-RNA sequencing. Our findings show the feasibility of our approach and that it can shorten the timeframe needed for the full selection process from weeks to days.

Citation Format: Eren Boga, Luisa Berger, Alice De Roia, Inka Zörnig, Robert Embacher, Stefan B. Eichmüller, Dirk Jäger, Richard Harbottle, Patrick Schmidt. A combination approach of a cellular library and single cell microfluidics analysis for the rapid selection of CAR-T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1769.

Perivascular tenascin C triggers sequential activation of macrophages and endothelial cells to generate a pro-metastatic vascular niche in the lungs

Disseminated cancer cells frequently lodge near vasculature in secondary organs. However, our understanding of the cellular crosstalk invoked at perivascular sites is still rudimentary. Here, we identify intercellular machinery governing formation of a pro-metastatic vascular niche during breast cancer colonization in the lung. We show that specific secreted factors, induced in metastasis-associated endothelial cells (ECs), promote metastasis in mice by enhancing stem cell properties and the viability of cancer cells. Perivascular macrophages, activated via tenascin C (TNC) stimulation of Toll-like receptor 4 (TLR4), were shown to be crucial in niche activation by secreting nitric oxide (NO) and tumor necrosis factor (TNF) to induce EC-mediated production of niche components. Notably, this mechanism was independent of vascular endothelial growth factor (VEGF), a key regulator of EC behavior and angiogenesis. However, targeting both macrophage-mediated vascular niche activation and VEGF-regulated angiogenesis resulted in added potency to curb lung metastasis in mice. Together, our findings provide mechanistic insights into the formation of vascular niches in metastasis.

Delivery of non-viral naked DNA vectors to liver in small weaned pigs by hydrodynamic retrograde intrabiliary injection

Hepatic gene therapy by delivering non-integrating therapeutic vectors in newborns remains challenging due to the risk of dilution and loss of efficacy in the growing liver. Previously we reported on hepatocyte transfection in piglets by intraportal injection of naked DNA vectors. Here, we established delivery of naked DNA vectors to target periportal hepatocytes in weaned pigs by hydrodynamic retrograde intrabiliary injection (HRII). The surgical procedure involved laparotomy and transient isolation of the liver. For vector delivery, a catheter was placed within the common bile duct by enterotomy. Under optimal conditions, no histological abnormalities were observed in liver tissue upon pressurized injections. The transfection of hepatocytes in all tested liver samples was observed with vectors expressing luciferase from a liver-specific promoter. However, vector copy number and luciferase expression were low compared to hydrodynamic intraportal injection. A 10-fold higher number of vector genomes and luciferase expression was observed in pigs using a non-integrating naked DNA vector with the potential for replication. In summary, the HRII application was less efficient (i.e., lower luciferase activity and vector copy numbers) than the intraportal delivery method but was significantly less distressful for the piglets and has the potential for injection (or re-injection) of vector DNA by endoscopic retrograde cholangiopancreatography.

IMMU-41. HIGH-THROUGHPUT RETRIEVAL OF THERAPEUTIC T CELL RECEPTORS FROM GLIOMA

Gliomas are tumors with low mutational burden with the majority of them being resistant to checkpoint inhibition due to few immunogenic antigens. Multicenter vaccine trials targeting personalized neoantigens in gliomas demonstrated feasibility and illustrated the challenges of retrieving neoepitope-specific T cells based on the prediction of immunogenic neoepitopes. Here we took an entirely different T cell-centric approach and established a single cell sequencing-based high-throughput T cell receptor (TCR) retrieval platform, exploiting the therapeutic potential of spontaneous intratumoral T cell clonotypes for the development of adoptive cell therapy. We conducted direct ex vivo TCR single cell sequencing from freshly sorted human glioma-infiltrating T cell samples. High fidelity PCR was established to clone TCRs from single cell libraries directly into episomal expression vectors further optimized for T cell therapy. In parallel to standard therapy, patient-derived xenografts were developed and characterized. Tumor-reactivity of retrieved TCRs was demonstrated against patient-derived cell lines. Collectively, we provide a novel sequencing-based platform for high-throughput identification and validation of endogenous glioma-targeting TCRs and demonstrate their therapeutic applicability.

Abstract 4717: Ly6-neurotoxin1 knockout in PDAC cells inhibits their growth in vitro and in vivo

Ly6/neurotoxin1 (Lynx1) functions as a brake for nicotinic receptors and was defined as a tumor suppressor in lung cancer. As pancreatic cancer development may be slowed down by cholinergic signaling, we investigated the role of Lynx1 in pancreatic ductal adenocarcinoma (PDAC) cell lines, both in vitro and in vivo. Lynx1 knockout cell clones were generated by transfecting the CRISPRCas9 plasmid - (pSpCas9 (BB)-2A-Puro) into Miapacaluci and BXPC3luci PDAC cells using jet Pei and jet Prime as transfecting agents, respectively. The annealed gRNA was directed towards exon 3 of the Lynx1 gene. Control clones were transfected with the plasmid alone. Clones from both cell lines were tested by qRT-PCR and Western blot for knockout efficiency as well as by proliferation assay. In addition, the expression levels of p-MEK, p-MAPK, p-mTOR and p-Rictor were verified in two BXPC3 cell clones in relation to Lynx1 expression. Furthermore, 4x106 cells of four BXPC3 cell clones (one control, 3 knockout clones) were injected, respectively, into the portal vein of nude rats to control for a possibly reduced tumor growth in the liver. The knockdown of Lynx1 was incomplete at mRNA level and ranged from 20 to 60% in BXPC3 clones and from 0 to 30% in Miapaca clones. At protein level, the respective values ranged from 0 to 90% in BXPC3 and from 22 to 50% in Miapaca clones. However, Lynx1 protein levels increased at later time points. All BXPC3 clones proliferated less quickly than the respective control when tested by MTT assay. Miapaca clones, however, didn't show a significant difference from the respective control, although their growth was clearly disturbed shortly after transfection. Concomitantly with reduced Lynx1 protein levels, there was reduction of p-mTOR (90%), p-Rictor (30%) and p-MEK (40%) in BXPC3 cells. In vivo, the BXPC3 clones showed a lag period of 1 to 2 weeks till the appearance of a first bioluminescence signal indicating tumor growth. Rats injected with cells from the control clone showed a steady increase in the bioluminescence signal (n=7 of 10) as compared to the most sensitive knockdown clone, which didn't show any signal in any of 4 injected rats (p=0.05). Cells of 2 other BXPC3 clones showed a reduced growth rate at best in 2 of 2 rats used for each clone, respectively. In conclusion, knockout of Lynx1 was incomplete at both mRNA and protein levels. Nevertheless, the respective BXPC3 clones exhibited reduced proliferation in vitro, which was associated with diminished p-mTOR, p-Rictor and p-MEK levels. In addition, they failed to establish a tumor in vivo or showed a reduced tumor growth rate. These findings suggest that Lynx1 is a vital gene and may play an important role in the growth and establishment of PDAC cells.

Citation Format: Doaa Ali, Michael Zepp, Matthias Bozza, Maria Nikolova, Richard Harbottle, Martin R. Berger. Ly6-neurotoxin1 knockout in PDAC cells inhibits their growth in vitro and in vivo [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4717.

Abstract 4066: A non-integrating, non-viral DNA Nanovector platform for the safe, persistent, and rapid manufacture of recombinant T-cells for Adoptive cell therapy

The capability to introduce Chimeric Antigen Receptors (CARs) into naïve Human T-Cells represents one of the most promising therapeutic strategies for the treatment of cancer. However, virus mediated adoptive cell therapy (ACT) remain severely limited by two factors: the long lead time and high cost of GMP virus manufacture, and the virus safety profiles. What if the entire ACT process could be sped up, made safer and more cost-effective by at least an order of magnitude? We have invented a novel DNA Vector platform based on scaffold/matrix attachment region (S/MAR) component that provides the opportunity to efficiently generate genetically engineered T-cells. This system is based on a nanovector technology. It contains no immunogenic and comprises only clinically approved sequences. It is easy, simple and cost-efficient to produce. Critically, it does not integrate and replicates autonomously and extrachromosomally in the nuclei of dividing primary human cells, thus avoiding the inherent risk of integrative mutagenesis. Through a process of iterative CpG depletion, selection marker minimalisation, empirical promoter design and elimination of cryptic eukaryotic signals our nano-S/MARt DNA Vector (nS/MARt) can be efficiently transfected into primary human T Cells. nS/MARt vectors are designed to remain stably expressed, and in addition to having the best in class safety profile, they also demonstrate enhanced performance as a biopharmaceutical. Human T-cells engineered to express the CAR receptor against the carcinoembryonic antigen (CEA) using a nS/MARt vector provide more effective killing of human cancer cells in vitro than those engineered with integrative lentivirus. These results hold in vivo, where nS/MARt transfected CAR Tcells outperform the lentivirally transduced cells, attenuating tumour growth and extending mouse survival. Moreover, in pre-clinical studies, the comparison with the FDA approved drug Kymriah®,T cells modified with nS/MARt vectors harbouring the expression of a CD19 CAR are comparable to those engineered with the viral vector. Notably, we have also taken steps to evaluate nS/MARt's scalability and have succeeded in manufacturing a clinically relevant number of CAR-T Cells (2 × 107CAR+ T-cells per kilo, we estimate the production for an individual of 80 Kg). The extension of the results from mice to patients-scale required a 1000x scale up for the processing of T-cell transfection while halving the time for production to hit a meaningful therapeutic window. We have developed a novel manufacturing protocol where nS/MARt vectors can be used "off the shelf" for CAR-T therapy to generate a clinically relevant number of modified cells in just seven days. The delivery of our DNA to CD3+ cells, reaches ~60-70% with cell viability of 60%, that increases in the days that follow the cell electroporation. Thus, the most significant benefit will be for the patients that will be able to access the nS/MARt mediated therapy in 1 week. To translate this technology into a clinical reality a fermentation process that allows the preparation of 2.6 g/L of pure, supercoiled DNA was optimised. There is a pressing need to offer ACT to more oncology patients, and we believe that this novel DNA Vector system provides a unique and innovative approach to this therapeutic strategy for cancer therapy.

Citation Format: Matthias Bozza, Alice De Roia, Aileen Berger, Alexandra Tuch, Patrick Schmidt, Richard Harbottle. A non-integrating, non-viral DNA Nanovector platform for the safe, persistent, and rapid manufacture of recombinant T-cells for Adoptive cell therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4066.

Abstract A042: A novel nonviral, nonintegrative DNA vector system for T-cell engineering

Adoptive immunotherapy is one of the most encouraging therapeutic strategies for the treatment of a range of cancers. A particularly promising avenue of research is the functional introduction of chimeric antigen receptors (CARs) into naive human T-cells for autologous immunotherapy. Currently, the genetic engineering of these cells is achieved through the use of integrating vector systems such as lentiviruses or the sleeping beauty transposon system, which present a potential risk of genotoxicity associated with their random genomic integration. We have invented a novel DNA vector platform for the safe and efficient generation of genetically engineered T-cells for human immunotherapy. This DNA vector system contains no viral components and comprises only clinically approved sequences; it does not integrate into the target-cell’s genome but it can replicate autonomously and extrachromosomally in the nuclei of dividing human primary cells. These DNA vectors offer several advantages over currently used vector systems; they are not subject to commercial licenses, they are cheaper and easier to produce, and they can more quickly genetically modify human cells without the inherent risk of integrative mutagenesis. In preclinical experiments we have successfully generated genetically engineered human T-cells that sustain the expression of a reporter gene for over a month at persistently high levels without decline. We have also successfully modified these cells with a range of transgenic CAR receptors against several known cancer cell epitopes and we have demonstrated their viability and capability in the targeted killing of these human cancer cells. We showed that CAR-T-cells generated with our technology killed more efficiently target cells when compared to T-cells engineered with current state-of-the-art integrative lentivirus. The expression of functional CARs was detected over a period of two weeks of administration in culture and the anticancer activity of our DNA-CAR-T-cells was evaluated in vivo using xenotransplanted cell lines in immunodeficient mice. We are currently performing analyses in order to determine the molecular behavior of the vector in the cells and its impact on cellular viability. Furthermore, we are developing a protocol for large scale electroporation in order to manufacture a clinical grade CAR-T DNA product. We believe that this novel DNA vector system provides a unique and innovative approach to this exciting therapeutic strategy for cancer therapy. We estimate that this novel methodology will provide a simpler method of CAR T-cell manufacturing, resulting in a 10-fold reduction in the cost of the CAR-T product.

Citation Format: Patrick Schmidt, Matthias Bozza, Dirk Jaeger, Richard Harbottle. A novel nonviral, nonintegrative DNA vector system for T-cell engineering [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A042.

Suppression of antitumor T cell immunity by the oncometabolite (R)-2-hydroxyglutarate

The oncometabolite (R)-2-hydroxyglutarate (R-2-HG) produced by isocitrate dehydrogenase (IDH) mutations promotes gliomagenesis via DNA and histone methylation. Here, we identify an additional activity of R-2-HG: tumor cell-derived R-2-HG is taken up by T cells where it induces a perturbation of nuclear factor of activated T cells transcriptional activity and polyamine biosynthesis, resulting in suppression of T cell activity. IDH1-mutant gliomas display reduced T cell abundance and altered calcium signaling. Antitumor immunity to experimental syngeneic IDH1-mutant tumors induced by IDH1-specific vaccine or checkpoint inhibition is improved by inhibition of the neomorphic enzymatic function of mutant IDH1. These data attribute a novel, non-tumor cell-autonomous role to an oncometabolite in shaping the tumor immune microenvironment.

Abstract 3573: Novel DNA vectors encoding a chimeric antigen receptor mediate long term expression without genomic integration

Adoptive immunotherapy is one of the most encouraging therapeutic strategies for the treatment of a range of cancers. One particularly promising avenue of research is the functional introduction of Chimeric Antigen Receptors (CARs) into naive Human T-Cells for autologous-immunotherapy. Currently, the genetic engineering of these cells is achieved through the use of proprietary integrating vector systems such as lentiviruses or the sleeping beauty transposon system which present a risk of genotoxicity associated with their random genomic integration.

We have invented a novel DNA Vector platform for the safe and efficient generation of genetically engineered T-Cells for Human Immunotherapy. This DNA vector system contains no viral components and comprises only clinically approved sequences, it does not integrate into the target cell's genome but it can replicate autonomously and extrachromosomally in the nucleus of dividing human primary cells. These DNA Vectors offer several advantages over currently used vector systems; they are not subject to commercial licences, they are cheaper and easier to produce, and they can more quickly genetically modify human cells without the inherent risk of integrative mutagenesis.

In preclinical experiments we have successfully generated genetically engineered human T-Cells expressing the CAR receptor against several epitopes and have demonstrated their viability and capability in targeting and killing human cancer cells which express these epitopes. The long term anti-tumor activity of our DNA-CAR-T cells has been confirmed in vivo using xenotransplanted cell lines in immunodeficient mice.

We believe that this novel DNA Vector system provides a unique and innovative approach to this exciting therapeutic strategy for cancer therapy. We estimate that this novel methodology will provide a simpler method of CAR T-cell manufacturing, resulting in a 10-fold reduction in the cost of the CART-product.

Citation Format: Patrick Schmidt, Matthias Bozza, Aileen Berger, Claudia Luckner-Minden, Alexandra Tuch, Inka Zörnig, Dirk Jäger, Richard Harbottle. Novel DNA vectors encoding a chimeric antigen receptor mediate long term expression without genomic integration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3573.

The expression of genes contributing to pancreatic adenocarcinoma progression is influenced by the respective environment

Pancreatic adenocarcinoma is a highly aggressive malignancy with dismal prognosis and limited curative options. We investigated the influence of organ environments on gene expression in RNU rats by orthotopic and intraportal infusion of Suit2-007luc cells into the pancreas, liver and lung respectively. Tumor tissues from these sites were analyzed by chip array and histopathology. Generated data was analyzed by Chipster and Ingenuity Pathway Analysis (±1.5 expression fold change and p<0.05). Further analysis of functional annotations derived from IPA, was based on selected genes with significant modulation of expression. Comparison of groups was performed by creating ratios from the mean expression values derived from pancreas and respective in vitro values, whereas those from liver and lung were related to pancreas, respectively. Genes of interest from three functional annotations for respective organs were identified by exclusion-overlap analyses. From the resulting six genes, transglutaminase2 (TGM2) was further investigated by various assays. Its knockdown with siRNA induced dose dependent inhibitory and stimulatory effects on cell proliferation and cell migration, respectively. DNA fragmentation indicated apoptotic cell death in response to TGM2 knockdown. Cell cycle analysis by FACS showed that TGM2 knockdown induced G1/S blockade. Therefore, TGM2 and its associated genes may be promising therapeutic targets.

Beta HPV38 oncoproteins act with a hit-and-run mechanism in ultraviolet radiation-induced skin carcinogenesis in mice

Cutaneous beta human papillomavirus (HPV) types are suspected to be involved, together with ultraviolet (UV) radiation, in the development of non-melanoma skin cancer (NMSC). Studies in in vitro and in vivo experimental models have highlighted the transforming properties of beta HPV E6 and E7 oncoproteins. However, epidemiological findings indicate that beta HPV types may be required only at an initial stage of carcinogenesis, and may become dispensable after full establishment of NMSC. Here, we further investigate the potential role of beta HPVs in NMSC using a Cre-loxP-based transgenic (Tg) mouse model that expresses beta HPV38 E6 and E7 oncogenes in the basal layer of the skin epidermis and is highly susceptible to UV-induced carcinogenesis. Using whole-exome sequencing, we show that, in contrast to WT animals, when exposed to chronic UV irradiation K14 HPV38 E6/E7 Tg mice accumulate a large number of UV-induced DNA mutations, which increase proportionally with the severity of the skin lesions. The mutation pattern detected in the Tg skin lesions closely resembles that detected in human NMSC, with the highest mutation rate in p53 and Notch genes. Using the Cre-lox recombination system, we observed that deletion of the viral oncogenes after development of UV-induced skin lesions did not affect the tumour growth. Together, these findings support the concept that beta HPV types act only at an initial stage of carcinogenesis, by potentiating the deleterious effects of UV radiation.

Many epidemiological and biological findings support the hypothesis that beta HPV types cooperate with UV radiation in the induction of NMSC, the most common form of human cancer. We have previously shown that K14 HPV38 E6/E7 Tg mice, when exposed to long-term UV radiation, developed NMSC, whereas WT animals subjected to identical treatments did not develop any type of skin lesions. Here, we show that the high skin cancer susceptibility of these Tg animals tightly correlates with their tendency to accumulate UV-induced mutations in genes that are frequently mutated in human NMSC. Importantly, deletion of the HPV38 E6 and E7 genes in existing skin lesions did not affect the further growth of the cancer cells. Together, these findings support the model that beta HPV infection is a co-factor in skin carcinogenesis, facilitating the accumulation of the UV-induced DNA mutations.

Abstract 644: Utilizing a novel luciferase labeling technique to establish and validate preclinical models of pancreatic cancer

Bioluminescent-labeling imaging (BLI) allows sensitive non-invasive sequential imaging of tumor development and early metastasis. Current methods for the genetic modification of cells typically use integrating genotoxic viruses that can disrupt the molecular behavior of cancer cell lines due to their random nature of integration. A primary aim of the study was to utilize a non-integrating DNA vector that comprises an S/MAR (Scaffold/Matrix Attachment Region) element to stably genetically modify pancreatic cancer cells to persistently express the reporter gene luciferase without altering the molecular behavior of the cell or altering its sensitivity to therapeutic drug treatments. Once a novel isogenic cell line is generated the cells can subsequently be used in xenograft studies. A second aim was to validate these established models with gemcitabine and test the efficacy of VAL401, formulation of risperidone in rumenic acid. Human BxPC3, Capan-1, MiaPaCa-2 and Panc-1 pancreatic cancer cells were stably transfected with a pSMARt-UBC-Luc DNA vector and cultured for 4 weeks under selection. Colonies that formed after this period were isolated and expanded in normal medium and evaluated for luciferase expression and the molecular integrity of the DNA vector. Efficacy of gemcitabine was tested in these new luciferase expressing cell lines and VAL401 was tested in Capan-1-luc cells. For in vivo studies, BxPC3-luc cells were inoculated orthotopically into the pancreas of athymic nude mice and stratified into groups: control, gemcitabine, VAL401 (1mg/kg, p.o. daily) and VAL401 (2mg/kg, p.o. daily). In vitro validation results indicated that the luciferase transfected cells maintained their original properties with stable expression. Gemcitabine inhibited cell proliferation in all established cell lines. VAL401 inhibited cell proliferation of Capan-1-luc cells at 50 μM concentration. BxPC3-luc cells inoculated orthotopically into the pancreas were followed for 5 weeks with BLI by IVIS, and the results demonstrated high-quality follow-up of tumor growth. BxPC3-luc cells induced growth of pancreatic tumors with high take rate in all groups. Gemcitabine and both studied doses of VAL401 decreased tumor volume, and the same trend was seen in tumor weight and the BLI during the study. In conclusion, both gemcitabine and VAL401 decreased tumor volume and the same trend was observed using BLI. Our results demonstrated that S/MAR DNA vectors are able to produce genetically modified cells without the limitations of random genomic integration, whilst providing extra-chromosomal mitotic stability and high levels of sustained transgene expression. When utilized in orthotopic xenograft studies, these luciferase expressing cells formed a reliable and essentially non-invasive imaging platform that substantially improves the efficacy of testing anticancer drug candidates.

Citation Format: Jenni Bernoulli, Matthias Bozza, Katja M. Fagerlund, Johanna Tuomela, Mari I. Suominen, Suzanne Dilly, George Morris, Jussi M. Halleen, Richard Harbottle. Utilizing a novel luciferase labeling technique to establish and validate preclinical models of pancreatic cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 644.

Abstract B69: VAL401 decreases tumor volume in a xenograft model of pancreatic cancer utilizing a novel improved luciferase labelling technique

Bioluminescent-labelling allows sensitive non-invasive sequential imaging of tumor development and early metastasis. Current methods for the genetic modification of cells typically use integrating genotoxic viruses that can potentially disrupt the molecular behavior of cancer cell lines due to their random nature of integration. VAL401 is the reformulation of a clinical drug to enable use in the treatment of cancer. Preclinical data indicate potential use of the reformulated drug in lung cancer, where many subsets of patients have currently a high unmet medical need. We have utilized a non-viral DNA vector that comprises an S/MAR (Scaffold/Matrix Attachment Region) element to stably modify cells to be further used in xenograft studies to allow long term expression without affecting cell behavior or silencing over cell divisions. Human BxPC3 pancreatic cancer cells were stably transfected with a pSMARt-UBC-Luc and cultured for 4 weeks under selection. Colonies that formed after this period were isolated and expanded in normal medium and evaluated for luciferase expression and molecular integrity of the DNA vector. For in vivo studies, BxPC3 cells were inoculated orthotopically into the pancreas of athymic nude mice. Four experimental groups were included in the study: 1) Control group receiving vehicle; 2) Reference compound gemcitabine (60 mg/kg, q3dx4 i.p, one week pause, q3dx4 i.p.); 3) Test compound VAL401 (1 mg/kg, p.o. daily); 4) Test compound VAL401 (2 mg/kg, p.o. daily). The luciferase transfected cells maintained their original properties with stable expression. Luciferase-labelled BxPC3 cells inoculated orthotopically into the pancreas were successfully followed for 5 weeks with non-invasive bioluminescence imaging by IVIS, and the results demonstrated high-quality follow-up of tumor growth compared with tumor models using non-labelled cells. BxPC3-luc cells induced growth of pancreatic tumors with high take rate in all groups. Gemcitabine and both studied doses of VAL401 decreased tumor volume, and the same trend was seen in tumor weight and the BLI parameters (total flux, area and average radiance) during the study. In conclusion, both gemcitabine and VAL401 decreased tumor volume and same trend was seen in BLI. Our results demonstrated that S/MAR DNA vectors are able to produce genetically modified cells without the limitations of random genomic integration, whilst providing extra-chromosomal mitotic stability and sustained transgene expression at high level. When utilized in orthotopic xenograft studies, these luciferase expressing cells formed a reliable and essential non-invasive imaging platform that improves substantially efficacy testing of anticancer drug candidates.

Citation Format: Mari I. Suominen, Jenni Bernoulli, Suzanne Dilly, Johanna Tuomela, Matthias Bozza, Katja M. Fagerlund, George Morris, Jussi M. Halleen, Richard Harbottle. VAL401 decreases tumor volume in a xenograft model of pancreatic cancer utilizing a novel improved luciferase labelling technique. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B69.

Abstract 3246: Novel luciferase labelling technique to improve imaging of orthotopic prostate and pancreatic cancer models

Bioluminescent-labelling allows sensitive non-invasive sequential imaging of tumor development and early metastasis. However, current methods for the genetic modification of cells typically use integrating genotoxic viruses that can potentially disrupt the molecular behavior of cancer cell lines due to their random nature of integration. Here, we utilized a non-viral DNA vector that comprises an S/MAR (Scaffold/Matrix Attachment Region) element to stably modify cells to be further used in xenograft studies to allow long term expression without affecting cell behavior or silencing over cell divisions. Human PC-3 prostate cancer cells and BxPC-3 pancreatic cancer cells were stably transfected with a pCAG-LUC-S/MAR and cultured for 4 weeks under selection. Colonies that formed after this period were isolated and expanded in normal medium and evaluated for luciferase expression and molecular integrity of the DNA vector. For in vivo studies, PC-3 cells were inoculated orthotopically into the prostate, and BxPC-3 cells into the pancreas using athymic and BALB/c nude mice. For comparison, similar experiments with the corresponding study designs were performed with the non-labelled parental cell lines. The luciferase transfected cells maintained their original properties with stable expression. Luciferase-labelled PC-3 and BxPC-3 cells inoculated orthotopically into the prostate and pancreas, respectively, were successfully followed for 5 weeks with non-invasive bioluminescence imaging by IVIS. The results demonstrated high-quality follow-up of tumor growth compared with tumor models using non-labelled cells. In conclusion, S/MAR DNA vectors are able to produce genetically modified cells without the limitations of random genomic integration, whilst providing extra-chromosomal mitotic stability and sustained transgene expression at high level. When utilized in orthotopic xenograft studies, these luciferase expressing cells formed a reliable and essential non-invasive imaging platform that improves substantially efficacy testing of anticancer drug candidates.

Citation Format: Jenni Bernoulli, Johanna Tuomela, Matthias Bozza, Katja M. Fagerlund, Mari I. Suominen, George Morris, Jussi M. Halleen, Richard Harbottle. Novel luciferase labelling technique to improve imaging of orthotopic prostate and pancreatic cancer models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3246. doi:10.1158/1538-7445.AM2015-3246

pH-triggered nanoparticle mediated delivery of siRNA to liver cells in vitro and in vivo

Recently, we reported for the first time the development of pH-triggered nanoparticles for the functional delivery of small interfering RNA (siRNA) to liver for treatment of hepatitis B virus infections in vivo. Here, we report on systematic formulation and biophysical studies of three different pH-triggered nanoparticle formulations looking for ways to improve on the capabilities of our previous nanoparticle system. We demonstrate how pH-triggered, PEGylated siRNA nanoparticles stable with respect to aggregation in 80% serum can still release siRNA payload at pH 5.5 within 30 min. This capability allows functional delivery to cultured murine hepatocyte cells in vitro, despite a high degree of PEGylation (5 mol %). We also demonstrate that pH-triggered, PEGylated siRNA nanoparticles typically enter cells by clathrin-coated pit endocytosis, but functional delivery requires membrane fusion events (fusogenicity). Biodistribution studies indicate that >70% of our administered nanoparticles are found in liver hepatocytes, post intravenous administration. Pharmacodynamic experiments show siRNA delivery to murine liver effecting maximum knockdown 48 h post administration from a single dose, while control (nontriggered) nanoparticles require 96 h and two doses to demonstrate the same effect. We also describe an anti-hepatitis C virus (HCV) proof-of-concept experiment indicating the possibility of RNAi therapy for HCV infections using pH-triggered, PEGylated siRNA nanoparticles.

LDLR-Gene therapy for familial hypercholesterolaemia: problems, progress, and perspectives

Coronary artery diseases (CAD) inflict a heavy economical and social burden on most populations and contribute significantly to their morbidity and mortality rates. Low-density lipoprotein receptor (LDLR) associated familial hypercholesterolemia (FH) is the most frequent Mendelian disorder and is a major risk factor for the development of CAD. To date there is no cure for FH. The primary goal of clinical management is to control hypercholesterolaemia in order to decrease the risk of atherosclerosis and to prevent CAD. Permanent phenotypic correction with single administration of a gene therapeutic vector is a goal still needing to be achieved. The first ex vivo clinical trial of gene therapy in FH was conducted nearly 18 years ago. Patients who had inherited LDLR gene mutations were subjected to an aggressive surgical intervention involving partial hepatectomy to obtain the patient's own hepatocytes for ex vivo gene transfer with a replication deficient LDLR-retroviral vector. After successful re-infusion of transduced cells through a catheter placed in the inferior mesenteric vein at the time of liver resection, only low-level expression of the transferred LDLR gene was observed in the five patients enrolled in the trial. In contrast, full reversal of hypercholesterolaemia was later demonstrated in in vivo preclinical studies using LDLR-adenovirus mediated gene transfer. However, the high efficiency of cell division independent gene transfer by adenovirus vectors is limited by their short-term persistence due to episomal maintenance and the cytotoxicity of these highly immunogenic viruses. Novel long-term persisting vectors derived from adeno-associated viruses and lentiviruses, are now available and investigations are underway to determine their safety and efficiency in preparation for clinical application for a variety of diseases. Several novel non-viral based therapies have also been developed recently to lower LDL-C serum levels in FH patients. This article reviews the progress made in the 18 years since the first clinical trial for gene therapy of FH, with emphasis on the development, design, performance and limitations of viral based gene transfer vectors used in studies to ameliorate the effects of LDLR deficiency.

Development of a Self-assembling Nuclear Targeting Vector System Based on the Tetracycline Repressor Protein

The ultimate destination for most gene therapy vectors is the nucleus and nuclear import of potentially therapeutic DNA is one of the major barriers for nonviral vectors. We have developed a novel approach of attaching a nuclear localization sequence (NLS) peptide to DNA in a non-essential position, by generating a fusion between the tetracycline repressor protein TetR and the SV40-derived NLS peptide. The high affinity and specificity of TetR for the short DNA sequence tetO was used in these studies to bind the NLS to DNA as demonstrated by the reduced electrophoretic mobility of the TetR.tetO-DNA complexes. The protein TetR-NLS, but not control protein TetR, specifically enhances gene expression from lipofected tetO-containing DNA between 4- and 16-fold. The specific enhancement is observed in a variety of cell types, including primary and growth-arrested cells. Intracellular trafficking studies demonstrate an increased accumulation of fluorescence labeled DNA in the nucleus after TetR-NLS binding. In comparison, binding studies using the similar fusion of peptide nucleic acid (PNA) with NLS peptide, demonstrate specific binding of PNA to plasmid DNA. However, although we observed a 2-8.5-fold increase in plasmid-mediated luciferase activity with bis-PNA-NLS, control bis-PNA without an NLS sequence gave a similar increase, suggesting that the effect may not be because of a specific bis-PNA-NLS-mediated enhancement of nuclear transfer of the plasmid. Overall, we found TetRNLS-enhanced plasmid-mediated transgene expression at a similar level to that by bis-PNA-NLS or bis-PNA alone but specific to nuclear uptake and significantly more reliable and reproducible.

Integrins and angiogenesis: unlocking the route to gene therapy

Angiogenesis is defined as the process of vascularization of a tissue, involving the development of new capillary blood vessels. Both the induction and inhibition of this process can have therapeutic benefits in various pathological conditions. Integrins are a structurally elaborate family of adhesion molecules; they participate in a wide range of biological processes, including angiogenesis. Endothelial cells are intimately involved in angiogenesis and are thought to mediate this function partially through the integrins on their cell membrane, which regulate cell-cell and cell-matrix contacts. Extensive research into elucidating the mechanisms involved in the angiogenesis process have led to the discovery of a growing number of genes encoding pro- and anti-angiogenic proteins. A variety of gene therapy approaches have been used to deliver many of these genes to induce or inhibit the angiogenesis process with varying levels of success. This review investigates whether targeting gene therapy vectors to integrin receptors found on endothelial cells is a viable means to improve the efficiency of the gene transfer process.

High-throughput Pyrosequencing of a phage display library for the identification of enriched target-specific peptides

Gene therapy clinical trials have highlighted the importance of specific cellular/tissue targeting of gene delivery vectors. Phage display libraries are powerful tools for the selection of novel peptide ligands as targeting moieties because of their high-throughput screening potential. However, a severe rate-limiting step in this procedure in terms of time, numbers, and cost is the sequence identification of selected phages. Here we describe the application of Pyrosequencing technology for sequencing phage isolates after panning a random 7-mer peptide expressing phage library against the A549 bronchial epithelial cell line to search for enrichment of possible targeting peptides. Pyrosequencing allows sequencing of 96 phages at one time in approximately 45 min at only a sixth of the cost of conventional sequencing methods. Using this technology, we have identified four sequences of interest. A phage binding assay revealed that three of the four sequences show a significant increase in binding abilities and specificity for A549 cells when compared to an unrelated cell line.

Surfactant levels after reversible tracheal occlusion and prenatal steroids in experimental diaphragmatic hernia

BACKGROUND/PURPOSE

In normal lungs, fetal tracheal occlusion (TO) induces lung growth but decreases the number of type II cells; this is remedied if TO is released (TR) before delivery. In the current study, the effects of TO with or without TR on pulmonary structure and surfactant were assessed in the ovine model in which lung hypoplasia was induced by creation of a diaphragmatic hernia (CDH).

METHODS

A left-sided CDH was created in fetal lambs at 80 days gestation; TO was done at 108 days; and TR at 129 days. All ewes were given 1 dose of glucocorticoids at 135 days. At 136 days, the fetus was delivered. Lung weight to body weight ratio, mean terminal bronchiole density, type II cell density, bronchoalveolar lavage fluid (BAL) phosphatidylcholine (PC), BAL surfactant protein A (SP-A) and B (SP-B), and lung tissue SP-A and SP-B were assessed in CDH, CDH with TO, CDH with TO and TR, and controls.

RESULTS

CDH lungs were hypoplastic and structurally immature, but had increased type II cell density. TO with or without TR caused lung growth with normalization of lung parenchymal architecture and type II cell density. Although the BAL SP-A and BAL SP-B were similar in all 4 groups, the BAL PC was low in CDH with or without TO or TR. Also, lung tissue SP-B levels were low in CDH with or without TO or TR. However, lung tissue SP-A levels were normal in CDH, but low in CDH with TO with or without TR.

CONCLUSIONS

Despite the finding that lung morphology was improved in CDH with TO with or without TR animals, surfactant content and composition remained abnormal. Although surfactant secreted early by the fetus into alveolar spaces contained normal levels of BAL SP-A and BAL SP-B, the low levels of BAL PC and low lung tissue stores of SP-B indicate that these experimental lambs may experience respiratory insufficiency soon after birth. This implies that prophylactic surfactant at birth might be beneficial for CDH.

Structural requirements of thiol compounds in the inhibition of human liver iodothyronine 5'-deiodinase

2-Thiouracil and a number of its alkyl derivatives are known to inhibit the enzymic 5'-deodination of thyroxine to 3,5,3'-tri-iodothyronine. The structural requirements for inhibition of iodothyronine 5'-deiodinase were investigated by using a washed postmitochondrial particulate fraction of human liver. A series of sulphur-containing derivatives of pyrimidine, pyridine, imidazole, benzene and urea, capable of existing in a thiol form, were incubated at several concentrations with the enzyme preparation in the presence of thyroxine and dithioerythritol (cofactor). The degree of inhibition by the respective compounds of the production of 3,5,3'-tri-iodothyronine was studied in relation to their structural features. The major observations were: (i) a free thiol group is essential; (ii) compounds that do not possess a polar hydrogen atom spatially configured so that it is proximal to the thiol group are poor inhibitors; (iii) aromatic characteristics in the presence of requirements (i) and (ii) lead to the expression of potent inhibitory properties; (iv) modification of potent inhibitors by the introduction of hydrophilic substituents reduces the inhibitory potency.