Treatment of multiple spontaneous breast tumors in mice using electrochemotherapy

Electrochemotherapy has been developed on the basis of in vitro data showing the huge increase of bleomycin cytotoxicity observed after cell electropermeabilization. Electrochemotherapy has been proven to be highly efficient as a local antitumor treatment on transplanted tumors (1). Indeed, electrochemotherapy resulted in high rates of tumor responses and even cures in preclinical trials on different experimental murine tumors (2). Treatment efficacy results from the local application of adequate electric pulses able to permeabilize the tumor cells located in the tissue volume crossed by the electric field, which allows the bleomycin present in tumor interstitial fluids to enter these cells and to kill them (3). Since the electric pulse delivery is designed to only reversibly permeabilize the tumor cells, electrochemotherapy is almost devoid of any side effects, and it can be safely proposed as a new antitumor treatment to be used in human clinics. Actually, a phase I-II clinical trial of electrochemotherapy has already given very satisfactory results on cutaneous tumors (4).