Effect of gene electrotransfer on expression of cytosolic DNA sensors in tumor and normal cells in vitro and in vivo

Za vnos plazmidne DNA (pDNA) v celice ali tkiva lahko uporabimo različne dostavne metode. Ena izmed teh je elektroporacija, oz. genski elektroprenos (GEP) oz. elektrogenska terapija. Pri GEP celice izpostavimo zunanjemu električnemu polju z določeno jakostjo in trajanjem ter pri tem vplivamo na prepustnost membrane. Pri zdravljenju rakavih sprememb se pri elektrogenski terapiji uporabljajo predvsem geni, ki vplivajo na imunski odgovor ali angiogenezo tumorja. Pri predhodnjih poskusih smo na mišjem modelu z GEP uspeli regresijo tumorja doseči tudi pri kontrolni skupini, kjer smo uporabili le plazmidno DNA, brez terapevtskega gena. Upočasnjeno rast in regresijo tumorja po GEP plazmidne DNA brez terapevskega gena so opazili tudi v drugih raziskavah. Ker plazmidna DNA brez terapevtskega gena ne nosi zapisa za terapevtski protein, do regresije tumorja ni prišlo zaradi terapevtskega učinka. Predvidevamo, da plazmidna DNA z GEP vstopi v celico z endocitozo ali skozi pore v membrani, ki nastanejo po izpostavitvi celice električnim pulzom. Celice citosolno DNA zaznajo s pomočjo citosolnih senzorjev DNA v celici. Po vstopu pDNA v celico se ob njeni vezavi na senzorje DNA sproži kaskada reakcij znotrajceličnega signaliziranja, ki vodi do prepisa genov, ki kodirajo vnetne citokine in interferone. Poleg prepisovanja genov lahko pride tudi do sprožitve različnih oblik celične smrti in sicer piroptoze, nekroptoze in apotoze. Prisotnost senzorjev DNA so dokazali v imunskih in v nekaterih neimunskih celicah.For the entry of pDNA into the cells and tissues we can use different delivery methodes. One of them is electroporation, eg. gene electrotransfer (GET), eg. electrogene therapy in which the cells are exposed to electric pulses with specific intensities and durations in order to increase the permeability of the cell membrane. In cancer electrogene therapy, genes that affect the immune system or angioginesis of the tumor are used. In our laboratory, we noticed a regression of tumors after electrogene therapy of mice in control groups, where we used only pDNA without any therapeutic gene. In other laboratories tumor growth delay and regression of tumors after GET of pDNA was also determined. Because pDNA has no terapeutic genes, regression is not due to therapeutic effect. It was predicted that after GET, pDNA enters the cell with endocytosis or through pores, that are established in the membrane after exposure to the electric field. After the entery of pDNA into the cells, the DNA sensors can bind to it and this leads to dfferent signal pathways, resulting in transcription of genes coding proimmlamatory cytokines, interferons and can also lead to different triggered cell deaths, such as piroptosis and necroptosis. The presence of DNA sensors was shown in immune cells and some of the non-immune cells

Evaluation of a novel plasmid for simultaneous gene electrotransfer-mediated silencing of CD105 and CD146 in combination with irradiation

Targeting tumor vasculature through specific endothelial cell markers represents a promising approach for cancer treatment. Here our aim was to construct an antibiotic resistance gene-free plasmid encoding shRNAs to simultaneously target two endothelial cell markers, CD105 and CD146, and to test its functionality and therapeutic potential in vitro when delivered by gene electrotransfer (GET) and combined with irradiation (IR). Functionality of the plasmid was evaluated by determining the silencing of the targeted genes using qRT-PCR. Antiproliferative and antiangiogenic effects were determined by the cytotoxicity assay tube formation assay and wound healing assay in murine endothelial cells 2H-11. The functionality of the plasmid construct was also evaluated in malignant melanoma tumor cell line B16F10. Additionally, potential activation of immune response was measured by induction of DNA sensor STING and proinflammatory cytokines by qRT-PCR in endothelial cells 2H-11. We demonstrated that the plasmid construction was successful and can efficiently silence the expression of the two targeted genes. As a consequence of silencing, reduced migration rate and angiogenic potential was confirmed in 2H-11 endothelial cells. Furthermore, induction of DNA sensor STING and proinflammatory cytokines were determined, which could add to the therapeutic effectiveness when used in vivo. To conclude, we successfully constructed a novel plasmid DNA with two shRNAs, which holds a great promise for further in vivo testing

A combination of electrochemotherapy, gene electrotransfer of plasmid encoding canine IL-12 and cytoreductive surgery in the treatment of canine oral malignant melanoma

The aim of this study was to evaluate the safety and efficacy of the combination of electrochemotherapy (ECT) with bleomycin and gene electrotransfer (GET) of plasmid encoding canine interleukin 12 (IL-12) for the treatment of canine oral malignant melanoma (OMM). Our focus was to determine the effect of the treatment on achieving local tumor control and stimulation of an antitumor immune response. Nine dogs with histologically confirmed OMM stage I to III were included in a prospective, non-randomized study. The dogs were treated with a combination of cytoreductive surgery, ECT and IL-12 GET, which was repeated up to five times, depending on the clinical response to the treatment, evaluated according to the follow-up protocol (7, 14 and 28 days after, the last treatment). One month after treatment, the objective response (OR) rate was 67% (6/9). Median survival time (MST) was 6 months and, even though the disease progressed in 8/9 patients at the end of the observation period (2 to 22 months), four animals were euthanized due to tumor-unrelated reasons. In addition, we observed a decline in the percentage of regulatory T cells (Treg) in the peripheral blood in the course of the treatment, which could be attributed to a systemic antitumor response to IL-12 GET. The results of this study suggest that a combination of ECT and IL-12 GET may be beneficial for dogs with OMM, especially when other treatment approaches are not acceptable due to their invasiveness or cost

In vitro and in vivo correlation of skin and cellular responses to nucleic acid delivery

Skin, the largest organ in the body, provides a passive physical barrier against infection and contains elements of the innate and adaptive immune systems. Skin consists of various cells, including keratinocytes, fibroblasts, endothelial cells and immune cells. This diversity of cell types could be important to gene therapies because DNA transfection could elicit different responses in different cell types. Previously, we observed the upregulation and activation of cytosolic DNA sensing pathways in several non-tumor and tumor cell types as well in tumors after the electroporation (electrotransfer) of plasmid DNA (pDNA). Based on this research and the innate immuno- genicity of skin, we correlated the effects of pDNA electrotransfer to fibroblasts and keratinocytes to mouse skin using reverse transcription real-time PCR (RT-qPCR) and several types of protein quantification. After pDNA electrotransfer, the mRNAs of the putative DNA sensors DEAD (AspGlu-Ala-Asp) box polypeptide 60 (Ddx60), absent in melanoma 2 (Aim2), Z-DNA binding protein 1 (Zbp1), interferon activated gene 202 (Ifi202), and interferon-inducible protein 204 (Ifi204) were upregulated in keratinocytes, while Ddx60, Zbp1 and Ifi204 were upregulated in fibroblasts. Increased levels of the mRNAs and proteins of several cytokines and chemokines were detected and varied based on cell type. Mouse skin experiments in vivo confirmed our in vitro results with increased expression of putative DNA sensor mRNAs and of the mRNAs and proteins of several cytokines and chemokines

Non-clinical in vitro evaluation of antibiotic resistance gene-free plasmids encoding human or murine IL-12 intended for first-in-human clinical study

Interleukin 12 (IL-12) is a key cytokine that mediates antitumor activity of immune cells. To fulfill its clinical potential, the development is focused on localized delivery systems, such as gene electrotransfer, which can provide localized delivery of IL-12 to the tumor microenvironment. Gene electrotransfer of the plasmid encoding human IL-12 is already in clinical trials in USA, demonstrating positive results in the treatment of melanoma patients. To comply with EU regulatory requirements for clinical application, which recommend the use of antibiotic resistance gene-free plasmids, we constructed and developed the production process for the clinical grade quality antibiotic resistance gene-free plasmid encoding human IL-12 (p21-hIL-12-ORT) and its ortholog encoding murine IL-12 (p21-mIL-12-ORT). To demonstrate the suitability of the p21-hIL-12-ORT or p21-mIL-12-ORT plasmid for the first-in-human clinical trial, the biological activity of the expressed transgene, its level of expression and plasmid copy number were determined in vitro in the human squamous cell carcinoma cell line FaDu and the murine colon carcinoma cell line CT26. The results of the non-clinical evaluation in vitro set the basis for further in vivo testing and evaluation of antitumor activity of therapeutic molecules in murine models as well as provide crucial data for further clinical trials of the constructed antibiotic resistance gene-free plasmid in humans

Gene therapy in oncology, first steps of development in Slovenia

Genska terapija postaja čedalje bolj zanimiva tudi v onkologiji. Med aplikacijami je morda najzanimivejša imunostimulacija. Pripravimo lahko plazmidno DNA, ki nosi zapis za različne imunostimulatorne molekule, ki jih vnesemo v celice tumorjev ali normalnih tkiv. Ta tkiva postanejo proizvajalci teh molekul, ki lahko delujejo lokalno ali pa se izločajo tudi sistemsko v krvni obtok. Ker plazmidna DNA ne prehaja celične membrane, so potrebni dostavni sistemi, virusni ali nevirusni. V naših študijah uporabljamo predvsem nevirusni dostavni sistem – elektroporacijo. Interlevkin 12 (IL-12) je eden od zanimivih citokinov, za katerega je znano protitumorsko delovanje s spodbujanjem imunskega odziva in antiangiogenim delovanjem. Namen projekta SmartGene.si je bil pripraviti plazmid z zapisom za interlevkin 12 (plazmid phIL12) in pripraviti vse potrebno za njegovo klinično testiranje za zdravljenje kožnih tumorjev. V konzorciju smo združili moči s partnerji z akademskega in industrijskega področja. Treba je bilo pripraviti plazmid za uporabo v humani onkologiji po zahtevah Evropske agencije za zdravila (EMA). Za prijavo klinične študije na Javno agencijo za zdravila in medicinske pripomočke (JAZMP) smo morali izvesti tudi vse neklinične raziskave o varnosti in učinkovitosti zdravila. Nato je bilo treba razviti postopek priprave zdravila, zagotoviti primerne prostore za pripravo in izvedbo postopka priprave zdravila. V treh letih smo dosegli vse te zastavljene cilje in dobili dovoljenje za izvajanje klinične študije na kožnih tumorjih, ki ga je izdala JAZMP na osnovi pozitivnega mnenja Komisije Republike Slovenije za medicinsko etiko. Zdaj poteka klinična študija faze I preizkušanja plazmida phIL12 na kožnih tumorjih glave in vratu z namenom preveriti varnost in sprejemljivost genskega elektroprenosa plazmida v tumorje. Cilj študije je prav tako določiti primeren odmerek zdravila, ki bi ga v nadaljnji klinični študiji uporabili kot adjuvantno zdravljenje k ablativnim terapijam, kot sta radioterapija ali elektrokemoterapija.Gene therapy is also attracting interest in oncology. Probably the most interesting approach is immunostimulation. Plasmid DNA can be constructed, which is coding for a specific immunostimulatory molecule, which is then delivered into the cells, either in tumour or normal tissue. The transfected tissue then becomes the producer of the molecules encoded in the plasmid. The product is then released from the cells, either locally or systemically into the bloodstream. Since plasmids have hampered transport through the plasma membrane, delivery systems are needed that are either viral or nonviral. In our studies we predominantly use the non-viral transfection system, based on electroporation of the cells. Interleukin 12 (IL-12) is a cytokine with well-known anti-tumour and anti-angiogenic function. Therefore, in the SmartGene.si project we wanted to construct a plasmid DNA which is coding for IL-12 (plasmid phIL12), and perform all the necessary testing and prepare the documentation for its clinical testing in the treatment of skin tumours. The SmartGene.si consortium comprises partners from academia and industry. In the project it was necessary to prepare the plasmid according to the European Medicinal Agency (EMA) recommendations. For the application for the study approval submitted to the Agency for Medical Products and Medical Devices of the Republic of Slovenia (JAZMP), it was necessary to perform pharmacological, pharmacokinetic, and efficiency testing of phIL12. Thereafter, we had to develop the process and the facility, and prepare the drug. During the last three years, we have achieved all the goals and obtained the approval of the JAZMP for clinical testing of the product phIL12 in humans. We also obtained the approval of the National Ethics Committee. Currently, we are testing phIL-12 in a Phase I clinical protocol on head and neck skin tumours, with the aim to test the safety and feasibility of intratumoral gene electrotransfer of the plasmid phIL12. Another goal of the study is to determine a suitable dose of plasmid that could be used in future studies as adjuvant treatment to ablative therapies such as radiotherapy or electrochemotherapy