CHANGING ELECTRODE ORIENTATION IMPROVES THE EFFICACY OF ELECTROCHEMOTHERAPY OF SOLID TUMORS IN MICE

Electrochemotherapy is a new and promising approach in treatment of tu mors employing locally applied high voltage d.c. electric pulses in co mbination with chemotherapeutic drugs. Increased permeability of the p lasma membrane, induced by electric pulses, enables the chemotherapeut ic drugs to enter into the cytosol, thus potentiating their anti-tumor effectiveness. In most of the studies published until now, trains of pulses were delivered via percutaneous parallel plate electrodes, so t hat the tumor was situated in between the electrodes. In our study the train of electric pulses was divided into two trains, the second one oriented perpendicularly to the first one. This changing of the electr ode orientation resulted in improved anti-tumor efficacy of the electr ochemotherapy: prolonged tumor growth delay and higher percentage of s hea and long term complete responses of the tumors. In this paper we a lso suggest a possible explanation for the observed effect, based on t he knowledge of electric field distribution in the tissue and induced transmembrane potential.