In vivo electroporation of plasmids encoding GM-CSF or interleukin-2 into existing B16 melanomas combined with electrochemotherapy induces long-term antitumour immunity

Abstract

When cancer cells, including melanoma cells, are genetically altered to secrete cytokines, irradiated and injected into subjects, long-term antitumour immunity is induced. Optimally, existing melanomas induced to produce cytokines in vivo could stimulate this same immune response. Although in vivo electroporation enhances plasmid expression, electroporation of plasmids encoding granulocyte-monocyte colony stimulating factor (GM-CSF) and interleukin-2 (IL2) into B16 mouse melanomas did not significantly alter tumour growth at the concentration tested. Electrochemotherapy, which causes short-term, complete regressions of treated tumour but no resistance to challenge, was combined with plasmid delivery. The combination treatment resulted in the induction of long-term immunity to recurrence and resistance to challenge in up to 25% of mice.

Local gene therapy of solid tumors with GM-CSF and B7-1 eradicates both treated and distal tumors

“…This suggests that electroporation of the solid tumors is not unduly traumatic and that the GM-CSF produced by the tumors did not induce systemic toxicity. This is in keeping with the observations of Heller et al, 5 who found that the level of GM-CSF resulting from delivered gene, while increased within the tumor, was not measurable in peripheral blood and did not induce systemic toxicity. It is also noteworthy that on observation of the mice for greater than 3 months after eradication of the tumors, there was no evidence of autoimmune disease, suggesting that, in this model, at least immune clearance of bulky tumors could be achieved while maintaining autoimmune control.…”

“…4 Other groups have examined the in vivo effects of coexpression of immune stimulatory molecules such as interleukin-2 (IL-2), GM-CSF and CD80 in various murine tumor models, with immune peptides either being expressed in vivo from genes, or by direct delivery of pharmaceutically derived molecules. 2,[5][6][7][8][9] The B7-1 (CD80) costimulatory molecule is usually expressed on the membrane of professional APCs, such as dendritic cells or B cells, initially binding to CD28 on CD4 þ (helper) T cells, and subsequently acting as a second signal following antigen-TCR engagement. 10,11 Tumor cells usually lack expression of CD80 and without this costimulatory signal, T cells may become clonally anergic when the TCR signal is delivered.…”

DNA electrotransfer: its principles and an updated review of its therapeutic applications

“…83,85 Noticeable concentrations of the cytokines Interleukin-2 and GM-CSF in tumours transfected with the corresponding genes have been measured. 59 The biological effects observed in the publications listed in Table 1 demonstrate the efficacy of the electrogenetherapy for the treatment of various diseases. Finally, DNA electrotransfer has also been used for biotechnological purposes.…”

Electroporation-mediated and EBV LMP1-regulated gene therapy in a syngenic mouse tumor model

“…19,29 Earlier data show that use of in vivo electroporation enhances plasmid DNA uptake in tumor tissue, resulting in expression within the tumor. [30][31][32][33] Furthermore, in vivo electroporation is a safe and nontoxic delivery system. 34 This has been used for the efficient delivery of plasmid DNA encoding chemotherapeutic agents, such as cytokine IL12, resulting in tumor regression, long-term animal survival, and resistance to challenge.…”