Electrochemotherapy combined with peritumoral interleukin-12 (IL-12) gene electrotransfer was used for treatment of mast cell tumours in 18 client-owned dogs. Local tumour control, recurrence rate, as well as safety of combined therapy were evaluated. One month after the therapy, no side effects were recorded and good local tumour control was observed with high complete responses rate which even increased during the observation period to 72%. IL-12 gene electrotransfer resulted in 78% of patients with detectable serum IFN-% and/or IL-12 levels. In the treated tumours vascular changes as well as minimal T-lymphocytes infiltration was observed. After 1 week, the plasmid DNA was not detected intra- or peritumorally and no horizontal gene transfer was observed. In summary, our study demonstrates high antitumour efficacy of electrochemotherapy combined with IL-12 electrotransfer, which also prevented recurrences or distant metastases, as well as its safety and feasibility in treatment of canine mast cell tumours.
COBISS.SI-ID: 2248059
A gene electrotransfer (GET) of interleukin 12 (IL-12) had already given good results when treating tumors in human and veterinary clinical trials. So far, plasmids used in veterinary clinical studies encoded a human or a feline IL-12 and an ampicillin resistance gene, which is not recommended by the regulatory agencies to be used in clinical trials. Therefore, the aim of the current study was to construct the plasmid encoding a canine IL-12 with kanamycin antibiotic resistance gene that could be used in veterinary clinical oncology. The validation of the newly constructed plasmid was carried out on canine malignant melanoma cells, which have not been used in GET studies so far, and on human malignant melanoma cells. Canine and human malignant melanoma cell lines were transfected with plasmid encoding enhanced green fluorescence protein at different pulse parameter conditions to determine the transfection efficiency and cell survival. The IL-12 expression of the most suitable conditions for GET of the plasmid encoding canine IL-12 was determined at mRNA level by the qRT-PCR and at protein level with the ELISpot assay. The obtained results showed that the newly constructed plasmid encoding canine IL-12 had similar or even higher expression capacity than the plasmid encoding human IL-12. Therefore, it represents a promising therapeutic plasmid for further IL-12 gene therapy in clinical studies for spontaneous canine tumors. Additionally, it also meets the main regulatory agencies% (FDA and EMA) criteria.
COBISS.SI-ID: 1989499
Electrochemotherapy (ECT) is a local approach which is used for treating solid tumors of different histologies. Its mechanism is based on cell membrane permeabilization by means of "electroporation". To achieve the "electroporation" of the cells, electric pulses are generated by a generator and delivered to the target tissue by the use of electrodes. Electroporation is a physical method which is used to introduce molecules, like cytostatic drugs, into the cells that could not pass the cell membrane on their own. In electrochemotherapy, currently, cisplatin and bleomycin are clinically used. Electrochemotherapy antitumor effectiveness is high, for example up to 100% complete response of canine mast cell tumors smaller than 2 cm3 was achieved. Additionally, electrochemotherapy can be used for the treatment of inoperable tumors. One of the important characteristics of electrochemotherapy is that it can be effective as a one-time treatment only. However, in the case of failure or partial tumor response it can be repeated several times with equal or improved effectiveness. Electrochemotherapy is already a standard treatment for cutaneous and subcutaneous tumors of various histologies in human and veterinary oncology. Furthermore, several clinical studies exploiting electrochemotherapy for deep-seated tumors are on-going.
COBISS.SI-ID: 2495867
Cancer immunotherapy is currently one of the leading approaches in cancer treatment. Gene electrotransfer of plasmids encoding interleukin 12 (IL-12) into the cells leads to the production of IL-12, which drives immune cell polarization to an antitumoral response. One of the cell types that shows great promise in targeting tumor cells under the influence of IL-12 cytokine milieu is that of macrophages. Therefore, the aim of this study was to evaluate gene electrotransfer of antibiotic resistance-free plasmid DNA-encoding murine IL-12 (mIL-12) in mice bearing aggressive B16F10 murine melanoma. IL-12 electrotransfer resulted in the complete long-term eradication of the tumors. Serum mIL-12 and murine interferon % (mIFN%) were increased after IL-12 gene electrotransfer. Further on, hematoxylin and eosin (HE) staining showed increased infiltration of immune cells that lasted from day 4 until day 14. Immunohistochemistry (IHC) staining of F4/80, MHCII, and CD11c showed higher positive staining in the IL-12 gene electrotransfer group than in the control groups. Immune cell infiltration into the tumors and the high density of MHCII- and CD11c-positive cells suggest an antitumor polarization of macrophages and the presence of antigen-presenting cells that contributes to the important antitumor effectiveness of IL-12.
COBISS.SI-ID: 2663547
The study was aimed to characterize tumor response after combined treatment employing electrochemotherapy with IL-12 gene electrotransfer in dogs with spontaneous mast cell tumors (MCT). Materials and methods. Eleven dogs with eleven MCTs were included in the study. Histological changes were investigated in biopsy specimens collected before the treatment (T0), and 4 (T1) and 8 weeks (T2) later. Cellular infiltrates were characterized immunohistochemically by using anti CD3, CD20, Foxp3 (Treg), CD68 and anti MHC-class II antibodies. Proliferation and anti-apoptotic activity of neoplastic cells were assessed using anti Ki-67 and Bcl-2 antibodies. Angiogenetic processes were investigated immunohistochemically by using anti Factor VIII and anti CD31 antibodies and micro vessel density quantification. Results. Histopathological examination of samples at T0 confirmed the diagnosis and the presence of scanty infiltrates consisted mainly of T-lymphocytes and macrophages. At T1 and T2 neoplastic cells were drastically reduced in 7/11 cases, small clusters of neoplastic cells were detected in 3/11 cases and 1/11 cases neoplastic cells were still evident. Proliferation activity of neoplastic cells was significantly reduced at T1 and T2 and expression of anti-apoptotic protein at T1. Microvessel density was drastically reduced in all samples after treatment. The number of T-lymphocytes increased at T1, although not significant, while Treg were significant higher at T1 and macrophages at T2. Conclusions. The combined electrochemotherapy and IL-12 gene electrotransfer effectively induced a cellular response against neoplastic cells characterized mainly by the recruitment of T-lymphocytes and macrophages and a fibrotic proliferation with reduction of microvessels.
COBISS.SI-ID: 2744443