CONICET | Buscador de Institutos y Recursos Humanos

Electrochemotherapy is a novel technique in medicine widely spread for treating superficial tumors regardless of its histology. One of the main limitations of this procedure is the difficulty in reaching deep-seated tumors with the proper electric field, this means a field that produces cell permeabilization. Usually, to achieve a permeabilization area of a considerable size, in the standard treatment multiple needles are placed around the tumor. The positioning of the needles is difficult and prone to errors due to electrode misalignment possibly leaving areas untreated that could lead to a relapse. According to the ESOPE study, the standard parameters are: 8 pulses of 1000 V/cm 100µs long at 1-5000Hz. In this work, we explore the increment of the permeabilized area when the number of pulses is augmented. For this end, we used the Single Needle Electrode (SiNE), an electrode that is easy to place in the tumor and can treat large portions of tissue, in a vegetal model (potato slices). Moreover, pH contribution for each set of pulses was studied using pH indicator dyes in gels. Results showed that optimum pulse parameters of 1000 V/cm 32 pulses 100µs long at 1 Hz induce a round permeabilization area 4.7 times the diameter of the electrode; extreme pH conditions in the surroundings of the needle were 2 times the diameter of the electrode. These results were tested in two canine patients with spontaneous occurring nasal tumors obtaining an objective response. In conclusion, the area of treatment can be increased by means of increasing the number of pulses. At the same time, this renders possible the use of lower voltages, thus induce less intense muscle contractions. This allows the treatment of an internal tumor of a considerable size with a single needle electrode using lower voltages depending on tumor size.