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Abstract: Gene therapy has become an important approach for treating cancer, and electroporation represents a technology for introducing therapeutic genes into a cell. An example of cancer gene therapy relying on gene electrotransfer is the use of immunomodulatory cytokines, such as interleukin 2 (IL-2) and 12 (IL-12), which directly stimulate immune cells at the tumour site. The aim of our study was to determine the effects of gene electrotransfer with two plasmids encoding IL-2 and IL-12 in vitro and in vivo. Two different pulse protocols, known as EP1 (600 V/cm, 5 ms, 1 Hz, 8 pulses) and EP2 (1300 V/cm, 100 %s, 1 Hz, 8 pulses), were assessed in vitro for application in subsequent in vivo experiments. In the in vivo experiment, gene electrotransfer of pIL-2 and pIL-12 using the EP1 protocol was performed in B16.F10 murine melanoma. Combined treatment of tumours using pIL2 and pIL12 induced significant tumour growth delay and 71% complete tumour regression. Furthermore, in tumours coexpressing IL-2 and IL-12, increased accumulation of dendritic cells and M1 macrophages was obtained along with the activation of proinflammatory signals, resulting in CD4 + and CD8 + T-lymphocyte recruitment and immune memory development in the mice. In conclusion, we demonstrated high antitumour efficacy of combined IL-2 and IL-12 gene electrotransfer protocols in low-immunogenicity murine B16.F10 melanoma.
Keywords: gene therapy, gene electrotransfer, IL-12, immunotherapy, melanoma
Published in DiRROS: 23.09.2022; Views: 330; Downloads: 110
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Abstract: Electrochemotherapy (ECT) exhibits high therapeutic effectiveness in the clinic, achieving up to 80% local tumor control but without a systemic (abscopal) effect. Therefore, we designed a combination therapy consisting of ECT via intratumoral application of bleomycin, oxaliplatin or cisplatin with peritumoral gene electrotransfer of a plasmid encoding interleukin-12 (p. t. IL-12 GET). Our hypothesis was that p. t. IL-12 GET potentiates the effect of ECT on local and systemic levels and that the potentiation varies depending on tumor immune status. Therefore, the combination therapy was tested in three immunologically different murine tumor models. In poorly immunogenic B16F10 melanoma, IL-12 potentiated the antitumor effect of ECT with biologically equivalent low doses of cisplatin, oxaliplatin or bleomycin. The most pronounced potentiation was observed after ECT using cisplatin, resulting in a complete response rate of 38% and an abscopal effect. Compared to B16F10 melanoma, better responsiveness to ECT was observed in more immunogenic 4%T1 mammary carcinoma and CT26 colorectal carcinoma. In both models, p. t. IL-12 GET did not significantly improve the therapeutic outcome of ECT using any of the chemotherapeutic drugs. Collectively, the effectiveness of the combination therapy depends on tumor immune status. ECT was more effective in more immunogenic tumors, but GET exhibited greater contribution in less immunogenic tumors. Thus, the selection of the therapy, namely, either ECT alone or combination therapy with p. t. IL-12, should be predominantly based on tumor immune status.
Keywords: electrochemotherapy, gene electrotransfer, interleukin-12
Published in DiRROS: 21.09.2022; Views: 347; Downloads: 102
Full text (7,82 MB)

Abstract: In situ vaccination is a promising immunotherapeutic approach, where various local ablative therapies are used to induce an immune response against tumor antigens that are released from the therapy-killed tumor cells. We recently proposed using intratumoral gene electrotransfer for concomitant transfection of a cytotoxic cytokine tumor necrosis factor-% (TNF%) to induce in situ vaccination, and an immunostimulatory cytokine interleukin 12 (IL-12) to boost the primed immune response. Here, our aim was to test the local and systemic effectiveness of the approach in tree syngeneic mouse tumor models and associate it with tumor immune profiles, characterized by tumor mutational burden, immune infiltration and expression of PD-L1 and MHC-I on tumor cells. While none of the tested characteristic proved predictive for local effectiveness, high tumor mutational burden, immune infiltration and MHC-I expression were associated with higher abscopal effectiveness. Hence, we have confirmed that both the abundance and presentation of tumor antigens as well as the absence of immunosuppressive mechanisms are important for effective in situ vaccination. These findings provide important indications for future development of in situ vaccination based treatments, and for the selection of tumor types that will most likely benefit from it.
Keywords: in situ vaccination, gene electrotransfer, interleukin 12, tumor necrosis factor [alfa]
Published in DiRROS: 19.09.2022; Views: 323; Downloads: 110
Full text (1,78 MB)

Abstract: 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.
Keywords: interleukin 12, gene electrotransfer, antibiotic resistance, plasmids
Published in DiRROS: 07.09.2022; Views: 264; Downloads: 147
Full text (4,73 MB)
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