Biological factors of the tumour response to electrochemotherapy: Review of the evidence and a research roadmap.

The beneficial effects of electrochemotherapy (ECT) for superficial tumours and, more recently, deep-seated malignancies in terms of local control and quality of life are widely accepted. However, the variability in responses across histotypes needs to be explored. Currently, patient selection for ECT is based on clinical factors (tumour size, histotype, and exposure to previous oncological treatments), whereas there are no biomarkers to predict the response to treatment. In this field, two major areas of investigation can be identified, i.e., tumour cell characteristics and the tumour microenvironment (vasculature, extracellular matrix, and immune infiltrate). For each of these areas, we describe the current knowledge and discuss how to foster further investigation. This review aims to provide a summary of the currently used guiding clinical factors and delineates a research roadmap for future studies to identify putative biomarkers of response to ECT. These biomarkers may allow researchers to improve ECT practice by customising treatment parameters, manipulating the tumour and its microenvironment, and exploring novel therapeutic combinations. • Electrochemotherapy is widely accepted therapeutic approach in terms of local tumor control and quality of life. • Currently the patient selecton is based on clinical factors, tumor size, histotype and exposure to previous treatments. • Biomarkers to predict tumor response to electrochemotherapy are needed. • For identification of potential biomarkers research on tumor cell characteristics and tumor stroma is needed. • Knowledge of putative biomarkers could improve electrochemotherapy practice, customize the treatment parameters and explore novel therapeutic combinations. [ABSTRACT FROM AUTHOR]