Antitumor in situ vaccination effect of TNF\u03b1 and IL-12 plasmid DNA electrotransfer in a murine melanoma model

Urska Kamensek,Katja Ursic,Gregor Sersa,Ursa Lampreht Tratar,Maja Cemazar

doi:10.1007/s00262-018-2133-0

Abstract

Gene electrotransfer (GET) is one of the most efficient non-viral gene therapy approaches for the localized transfer of multiple genes into tumors in vivo; therefore, it is especially promising for delivering different cytokines that are toxic if administered systemically. In this study, we used concomitant intratumoral GET of two cytokines: tumor necrosis factor alpha (TNFα), a potent cytotoxic cytokine to induce in situ vaccination, and interleukin 12 (IL-12), an immunostimulatory cytokine to boost the primed local immune response into a systemic one. After performing GET in murine melanoma tumors, both TNFα and IL-12 mRNA levels were significantly increased, which resulted in a pronounced delay in tumor growth of 27 days and a prolonged survival time of mice. An antitumor immune response was confirmed by extensive infiltration of immune cells in the tumor site, and expansion of the effector immune cells in the sentinel lymph nodes. Furthermore, the effect of in situ vaccination was indicated by the presence of vitiligo localized to the treatment area and resistance of the mice to secondary challenge with tumor cells. Intratumoral GET of two cytokines, one for in situ vaccination and one for an immune boost, proved feasible and effective in eliciting a potent and durable antitumor response; therefore, further studies of this approach are warranted.

Highlights

Gene electrotransfer (GET) is one of the most efficient non-viral gene therapy approaches that has already reached clinical evaluation
This study examined the concomitant intratumoral GET of TNFα and interleukin 12 (IL-12) plasmids
The tested treatments were: TNFα GET monotherapy (TNF), interleukin 12 monotherapy (IL-12) that consisted of two IL-12 GET treatments performed twice, with an interval of 6 days, and a combination in which both cytokines were first delivered concomitantly in one GET session, followed 6 days later by IL-12 GET (TNFα + IL-12) (Fig. 1)

Summary

Introduction

Gene electrotransfer (GET) is one of the most efficient non-viral gene therapy approaches that has already reached clinical evaluation (https://clinicaltrials.gov) Using this approach, genetic material encoded on plasmid vectors can be transferred across the cell membrane by applying electric pulses to the system (i.e., electroporation) [1]. In addition to a good safety profile, one of the advantages of GET is its ability to deliver genes directly into various target tissues, including tumors. Since it allows for local delivery, GET has proven itself as an especially effective method to deliver different cytokines that are toxic if delivered systemically as recombinant proteins. We wanted to test if local ablative therapy via GET of a gene encoding a cytotoxic product could be used for in situ vaccination in combination with IL-12 boost

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Conclusion