IL-12 Gene Therapy Using an Electrically Mediated Nonviral Approach Reduces Metastatic Growth of Melanoma

Abstract

Interleukin-12 (IL-12) has been evaluated in both preclinical and clinical immunotherapy protocols as a potential therapy for melanoma. However, delivery of IL-12 in the form of recombinant protein can result in severe toxicity, and gene therapy has had limited success against B16.F10 murine melanoma. This study investigated the therapeutic effect of delivering a plasmid encoding IL-12 followed by electroporation on primary and secondary tumors. Three treatments of intratumoral (i.t.) plasmid injection and electroporation resulted in 80% of mice with B16.F10 melanoma tumors being tumor free for >100 days (cure). The "cured animals" were resistant to challenge with B16 cells. In a separate experiment, B16 cells were injected on the opposite flank of the treated tumor on the day of treatment. Eighty-seven percent of control mice developed a distant tumor while only 43.8% of mice receiving two or three i.t. electroporation treatments developed a distant tumor. For examination of tumor development in the lungs, mice were injected intravenously with B16.F10 cells then treated with i.m. injections of plasmid with or without electroporation. Only 37.5% of mice receiving i.m. injections and electroporation developed nodules in the lungs compared to 87.5% of mice in the no-treatment group. The results show that administration of a plasmid encoding IL-12 with electroporation has a therapeutic effect on primary tumors as well as distant tumors and metastases.

Nanosecond pulsed electric fields cause melanomas to self-destruct

“…When the electric field across a cellular membrane exceeds about 1 V (2 kV/cm for a cell 10 μm in diameter), water-filled pores form in the membrane's lipid bilayer and the size and lifetime of these pores are dependent on the strength and duration of the electric field pulse. For amplitudes exceeding 2 kV/cm and pulse durations in the millisecond range, large pores form resulting in electroporation of the membrane that has been used to introduce normally impermeant anticancer drugs into targeted tissues [3][4][5]16]. For these long pulses, the pulse amplitude is limited to about 2 kV/cm to avoid thermal effects.…”

“…Some of these involve radiofrequency or microwave devices that heat the tumor to greater than 43 °C to kill the cells via hyperthermia [1,2]. Others use pulsed electric fields to permeabilize the tumor cells to allow the introduction of toxic drugs or DNA [3][4][5]. We have discovered that ultrashort electrical pulses can be used as a purely electrical cancer therapy that kills tumors without hyperthermia or drugs.…”

Control by pulse parameters of DNA electrotransfer into solid tumors in mice

“…7,8 Classically, electrically mediated gene delivery is obtained by submitting the target to a train of pulses lasting a few milliseconds or 100 microseconds at a 1 Hz frequency, and adjusting the voltage to the electrode width. [10][11][12][13][14][15][16] A new protocol with high transfection efficacy in muscle and skin has recently been described, consisting of a combination of one high-field (HV, B1000 V cm À1 ) and one (or several) low-field (LV, B100 V cm À1 ) pulse. [17][18][19][20][21][22][23] For simplicity, we called all along the paper 'field' what indeed is the voltage to electrode width ratio, that is, an experimentally controlled parameter.…”

Melanoma Treatment with Intratumoral Electroporation of Tavokinogene Telseplasmid (pIL-12, Tavokinogene Telseplasmid)

“…Electroporation of pIL-12 DNA has been demonstrated to yield high levels of IL-12 expression [41] leading to IFN-γ-mediated tumor cell killing [42,43], immune cell recruitment [41] and objective tumor regressions in animal models [43][44][45] including regression of untreated lesions [46]. In vivo tumor regressions have been durable and treated animals may be resistant to tumor reimplantation suggesting that intratumoral electroporation of pIL-12 DNA induces memory immune responses in these models [47,48]. Although intramuscular electroporation of pIL-12 has been examined, intratumoral therapy leads to more elaboration of cytokines in the tumor microenvironment and higher rates of tumor regressions [49,50].…”

“…Administration of intratumoral pIL-12-EP as a single treatment cycle was shown to significantly delay tumor growth [61]. Complete tumor regression was achieved with two and three treatment cycles [47,62]. Mice treated with pIL-12-EP experienced prolonged survival, and in some studies showed complete regression and remained disease-free for 50 days post treatment.…”