Bases and rationale of the electrochemotherapy

Abstract

Electrochemotherapy (ECT) is a non-thermal tumour ablation modality. ECT is safe and effective on any type of solid tumour. ECT is based on the achievement of in vivo tumor cell electropermeabilization by means of electric pulses locally delivered to the tumors. ECT is also based on the use of non-permeant drugs possessing high intrinsic cytotoxicity (such as bleomycin), or low-permeant drugs with known efficacy (such as cisplatin), which act directly on the cellular DNA. These drugs have to be injected before the electric pulses delivery. Cell electropermeabilisation, a physical procedure that affects all tumor cell types, allows these anticancer drugs to enter the cells, thus magnifying their cytotoxicity by orders of magnitude. However, there are other reasons explaining why this treatment is simple, safe and efficient. Selectivity towards the dividing tumour cells and safety of the procedure are due to the fact that, at least for the bleomycin injected intravenously, treatment causes a mitotic cell death that rapidly kills the dividing tumor cells and spares the neighboring non-dividing normal cells. Safety is also due to the vascular effects of the electric pulses: ECT provokes a transient vascular lock which prevents further bleeding, and even stops previous bleeding in the case of hemorrhagic nodules. As for efficacy, ECT efficacy is also sustained by a response of the host immune system, probably due to the type of cell death caused by the ECT. ECT is very well tolerated by the patients, and why its efficacy is very high on the treated nodules, whatever the tumour histological origin. Its use is presently standardized to skin and subcutaneous localisations.