IL-12 Gene Electrotransfer Triggers a Change in Immune Response within Mouse Tumors

Abstract

Metastatic melanoma is an aggressive skin cancer with a relatively low survival rate. Immune-based therapies have shown promise in the treatment of melanoma, but overall complete response rates are still low. Previous studies have demonstrated the potential of plasmid IL-12 (pIL-12) delivered by gene electrotransfer (GET) to be an effective immunotherapy for melanoma. However, events occurring in the tumor microenvironment following delivery have not been delineated. Therefore, utilizing a B16F10 mouse melanoma model, we evaluated changes in the tumor microenvironment following delivery of pIL-12 using different GET parameters or injection of plasmid alone. The results revealed a unique immune cell composition after intratumoral injection of pIL-12 GET. The number of immune memory cells was markedly increased in pIL-12 GET melanoma groups compared to control group. This was validated using flow cytometry to analyze peripheral blood mononuclear cells as well as delineating immune cell content using immunohistochemistry. Significant differences in multiple cell types were observed, including CD8+ T cells, regulatory T cells and myeloid cells, which were induced to mount a CD8+PD1− T cells immune response. Taken together, these findings suggest a basic understanding of the sequence of immune activity following pIL-12 GET and also illuminates that adjuvant immunotherapy can have a positive influence on the host immune response to cancer.

Intratumoral Gene Electrotransfer of Plasmid DNA Encoding shRNA against Melanoma Cell Adhesion Molecule Radiosensitizes Tumors by Antivascular Effects and Activation of an Immune Response

“…Specifically, in B16F10 melanoma, approximately 70% of animals were cured after GET with plasmid DNA (VR1255), and 70% of them were resistant to secondary challenge, suggesting the generation of an adaptive antitumor response [50]. However, this induction of immune response was more pronounced in the GET of therapeutic plasmids, as indicated in our study and others [26,36,37,42,51,55]. In a study silencing endoglin using the GET of a plasmid-encoding shRNA against endoglin under a tissue-specific promoter in the same melanoma tumor model B16F10, complete, long-term regression was found in 44% of tumors.…”

“…A possible mechanism for this antitumor effect is the activation and upregulation of several cytosolic DNA sensors as a response to foreign DNA in the cells, acting as DAMPs (damage-associated molecular patterns) [28,29,48], inducing also the translation of several proinflammatory cytokines, such as type 1 interferons, TNF-α, and other cytokines [49]. This can enhance the non-specific killing of tumor cells by the innate immune system, enhance the presentation of tumor antigens, recruit cells of the adaptive immune system, and generate long-term memory against recurring tumor cells [50][51][52][53][54]. Specifically, in B16F10 melanoma, approximately 70% of animals were cured after GET with plasmid DNA (VR1255), and 70% of them were resistant to secondary challenge, suggesting the generation of an adaptive antitumor response [50].…”

“…Similar effects were demonstrated with GET of plasmid encoding IL-12 curing 47% of B16F10 tumors, of which 70% were resistant to secondary challenge [42], and in SA-1 sarcoma, where 50% cured animals were obtained, which were all resistant to secondary challenge [37]. Furthermore, by optimizing the electrotransfer protocol for GET of plasmid encoding IL-12 in the same tumor model (B16F10), long-term regression can be improved, resulting in around 80% cured animals, of which 50% were resistant to secondary challenge [51].…”

Multiantigenic Nanoformulations Activate Anticancer Immunity Depending on Size

“…Tumor volumes and body weights were detected every other day. Tumor volume was calculated according to Equation . To investigate the efficacy of different nanovaccine formulations in preventing tumor metastasis, on day 28, three mice of each group were sacrificed to get the major organs to detect the metastatic lesions by the H&E‐stained slices.…”

Electrotransfer of siRNA to Silence Enhanced Green Fluorescent Protein in Tumor Mediated by a High Intensity Pulsed Electromagnetic Field

“…Applying electroporation to facilitate intracellular delivery of cytotoxic drugs, such as bleomycin and cisplatin, is known as electrochemotherapy [8]. Besides enabling delivery of genes with immunomodulatory effects or drugs to target cells, gene electrotransfer and electrochemotherapy are able to induce immune response, leading to an antitumor effectiveness [9][10][11]. Over the past several years, electroporation was successfully translated to veterinary and human clinics [12][13][14].…”