Clinical Applications and Immunological Aspects of Electroporation-Based Therapies

Reversible electropermeabilization (RE) is an ultrastructural phenomenon that transiently increases the permeability of the cell membrane upon application of electrical pulses. The technique was described in 1972 by Neumann and Rosenheck and is currently used in a variety of applications, from medicine to food processing. In oncology, RE is applied for the intracellular transport of chemotherapeutic drugs as well as the delivery of genetic material in gene therapies and vaccinations. This review summarizes the physical changes of the membrane, the particularities of bleomycin, and the immunological aspects involved in electrochemotherapy and gene electrotransfer, two important EP-based cancer therapies in human and veterinary oncology.

Electrochemotherapy as a New Modality in Interventional Oncology: A Review

Electroporation is a well-known phenomenon that occurs at the cell membrane when cells are exposed to high-intensity electric pulses. Depending on electric pulse amplitude and number of pulses, applied electroporation can be reversible with membrane permeability recovery or irreversible. Reversible electroporation is used to introduce drugs or genetic material into the cell without affecting cell viability. Electrochemotherapy refers to a combined treatment: electroporation and drug injection to enhance its cytotoxic effect up to 1000-fold for bleomycin. Since several years, electrochemotherapy is gaining popularity as minimally invasive oncologic treatment. The adoption of electrochemotherapy procedure in interventional oncology poses several unsolved questions, since suitable tumor histology and size as well as therapeutic efficacy still needs to be deepen. Electrochemotherapy is usually applied in palliative settings for the treatment of patients with unresectable tumors to relieve pain and ameliorate quality of life. In most cases, it is used in the treatment of advanced stages of neoplasia when radical surgical treatment is not possible (eg, due to lesion location, size, and/or number). Further, electrochemotherapy allows treating tumor nodules in the proximity of important structures like vessels and nerves as the treatment does not involve tissue heating. Overall, the safety profile of electrochemotherapy is favorable. Most of the observed adverse events are local and transient, moderate local pain, erythema, edema, and muscle contractions during electroporation. The aim of this article is to review the recent published clinical experiences of electrochemotherapy use in deep-seated tumors with particular focus on liver cases. The principle of electrochemotherapy as well as the application to cutaneous metastases is briefly described. A short insight in the treatment of bone metastases, unresectable pancreas cancer, and soft tissue sarcoma will be given. Preclinical and clinical studies on treatment efficacy with electrochemotherapy of hepatic lesions and safety of the procedure adopted are discussed.