ID: 2208

• Title:
  Enhanced Electrotransfer Approach for Delivery of Therapeutic Molecules to Tumors
  
  Authors:
  

  Heller, Richard, University of South Florida
  Heller, Loree, University of South Florida
  Shi, Guilan, University of South Florida
  Synowiec, Jody, University of South Florida
  Singh, Julie, University of South Florida
  Mannarino, Samantha, University of South Florida
  Otten, Alex, University of South Florida
  Jaroszeski, Mark J., University of South Florida

  
  
  Abstract:
  Background and objectives of the study: Gene electrotransfer (GET) has been used to successfully deliver plasmid DNA to multiple tissue targets. GET has been utilized as the delivery tool in over 100 clinical trials evaluating its use for multiple indications. While this demonstrates the utility of the approach, there is still room to improve the technology and enhance the results. Our research group has developed new concepts to the electrotransfer approach to enhance its utilization in multiple applications. The new approach incorporates the application of moderate heat (43oC) to the target tissue as well as the ability to monitor the tissue in a manner that provides a signal indicating when cells have been permeabilized. The addition of moderate heat has multiple advantages including enabling a reduced voltage which in turn would enable either a direct reduction in the applied voltage or treating a larger area with the same voltage. Heat also makes the application of the therapy more uniform across the tissue. In addition, when electric pulses are applied, the impedance of the tissue is reduced. We have developed a means to utilize this aspect to determine when the tissue has been sufficiently permeabilized based on a specific reduction in the impedance. Current work has been focused on using the system to develop immunotherapy protocols for solid tumors.
  
  
  
  Methods: The system includes a pulse generator, heat source and a means to measure impedance. The system also includes an array that incorporates independently addressable electrodes. The application of heat, electric pulses and impedance monitoring are all applied through this novel array. The system was tested in C57Bl/6 mice. Melanoma tumors were induced by injecting 1X106 B16.F10 melanoma cells into the flank of the mice. Once tumors were of sufficient size (4-7 mm diameter), treatment was initiated. Various aspects were tested including applied voltage and the use of heat and/or impedance.
  
  
  
  Results: While the new system can be used to deliver nucleic acid-based vaccines and protein replacement therapy in addition to other applications, we focused on testing its potential for immunotherapy applications for the treatment of solid tumors. We have previously demonstrated that GET could be used to deliver a plasmid encoding IL-12 (pIL-12). This documented the potential of the basic technology. Delivery was performed utilizing 1300 V/cm, 100 us pulses. We focused on reduced the necessary field to achieve complete response. Delivery of pIL-12 with the new approach resulted in 100% long-term complete regression and 100% protection from challenge using electric fields that are less than half (600 V/cm) of what was used previously. In addition, monitoring impedance within each independent section reveals different pulse numbers are needed to achieve delivery in each section. This has increased the reliability and reproducibility of the approach. Combining this approach with the delivery of checkpoint inhibitors has also increased response rates of secondary tumors.
  
  
  
  Conclusions: The results obtained in this study demonstrated the effectiveness of this device to deliver plasmid DNA to solid tumors and to induce a robust immune response. In addition, the utilization of this enhanced approach enables a more controlled delivery and application of the pulse fields that could be utilized in other electrically based therapeutics applications. This would include in normal tissue.
  
  
  
  Keywords:
  Gene Transfer, Immunotherapy, Electrotransfer
  
  Refs:
  
  
  Topic 1:
  12. Biomedical applications
  
  Topic 2:
  6. Cancer treatment and tumor ablation