## 4 Preclinical Studies  
A study by [PERSON] et al. revealed that electroporation augments the cytotoxicity of some anti-cancer drugs by increased uptake due to plasma membrane permeabilization. The experiment was conducted on carcinoma cells using chemotherapeutic agents--bleomycin, carboplatin, and cisplatin. The results are very auspicious because the cytotoxic effect of some drugs was remarkably heightened. For example, it was shown that the IC50 of bleomycin is significantly diminished (100-5000 times) when exposed to electric pulses. Cisplatin also showed immense progress--while transfected with electrical pulses, it presented improved cytotoxicity, and its IC50 was decreased in six of seven used cell lines. Carboplatin might also be considered as a choice due to its enhanced outcome in four of five examined carcinoma cell types [64]. Likewise, the study conducted by [PERSON] et al. showed superior cytotoxicity against human microvascular endothelial cells (HMEC-1) while cells were being exposed to electric pulses in comparison without them. A utilization of electroporation resulted in a 5000-fold curtailed IC50 value of bleomycin and a 10-fold diminished IC50 value of cisplatin [65]. Furthermore, [PERSON] et al. and [PERSON] et al. found the analog effect. The first research on uveal melanoma cells revealed elevated chemotherapeutic drugs' cytotoxicity and simultaneously highly diminished cancer cell viability. Additionally, it was proven that electroporation alone is capable of reducing melanoma cells' feasibility of survival by 25-29% [65]. The latter showed that the usage of electric fields on two different lines of pancreatic cancer cells--PANC1 and MiaPaCa2--resolved their heightened sensitivity for desired drugs along with decreased IC50 of them and lower cell's viability as well [66]. Another engaging study advocating the use of electrochemotherapy was performed by [PERSON] et al. The research group tried to determine the effect of cisplatin's action on mouse skin cell melanoma (B16-F1) with and without an electric field. They proved that with the force used, cisplatin's effect on cells was stronger, even though the used therapeutic dosage was small. Furthermore, the higher the concentration of the drug was, the less neoplasm's cells survived, whereas the same increase of chemotherapeutic dose without the electric field barely changed the survival ratio. Additionally, they found that a few different types  
Figure 3: Schematic visualization of the chain of events that arises while deploying intratumoral ECT and peritumoral immunogen electrotransfer [63]. The Figure was partly generated using Servier Medical Art, provided by Servier, licensed under a Creative Commons Attribution 3.0 unported license. of electric pulses (like short bipolar (HF-EP) or monopolar pulses) are able to effectively increase cell membrane permeability and decrease cell's survival as well [67]. Numerous in vitro and in vivo studies also successfully demonstrated the efficiency of immunogen electrotransfer. The in vitro research concerning GET of plasmid encoding IL-12 in combination with IL-2 in the B16.F10 murine melanoma cell line substantiated its feasibility. The EP led to lowered survival of the melanoma cells, whereas the cytotoxicity of the IL-2 and IL-12 plasmids was comparable to control plasmids, by using it can be stated that the presence of external DNA mainly induces the cytotoxic effect. Moreover, IL-12 and IL-2 mRNA and proteins were ascertained only in cells subjected to GET of these plasmids. The level of transcripts and proteins was more elevated after using EP1 protocol with longer and lower voltage pulses. These pulses are more noxious to the cells and augment the uptake of the plasmids. Due to the high cytotoxicity of EP1, it may be more efficient in tumor elimination than the EP2 protocol, based on short and high voltage pulses commonly used in ECT. However, the cytotoxicity and expression efficacy estimated in vitro may differ from the in vivo results [68].