Bases and rationale of the electrochemotherapy

Electrochemotherapy (ECT) is a non-thermal tumour ablation modality, safe and effective on any type of solid tumour. Its use is presently standardized to skin and subcutaneous localisations. ECT is 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. ECT is also based on the achievement of in vivo tumor cell electropermeabilization by means of electric pulses locally delivered to the tumors after bleomycin or cisplatin injection. 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. Efficacy is also sustained by a response of the host immune system, probably due to the type of cell death caused by the ECT. 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, explaining selectivity towards the dividing tumour cells and safety of the procedure. 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. These bases explain why ECT is safe and very well tolerated by the patients, and why its efficacy is very high on the treated nodules, whatever the tumour histological origin.