Percutaneous Irreversible Electroporation: Long-term survival analysis of 71 patients with inoperable malignant hepatic tumors

Clinical and safety outcomes in unresectable, very early and early-stage hepatocellular carcinoma following Irreversible Electroporation (IRE) and Transarterial Chemoembolization (TACE): A systematic literature review and meta-analysis

BACKGROUND

Locoregional treatments for early-stage unresectable hepatocellular carcinoma (HCC) are widely used, with irreversible electroporation (IRE) and transarterial chemoembolization (TACE) representing two non-thermal treatment options. However, to date, no systematic evaluations of these technologies have been conducted. This study sought to comparatively assess the safety and effectiveness of IRE and TACE for the treatment of very early and early-stage, inoperable HCC via systematic literature reviews (SLRs) and meta-analyses.

METHODOLOGY

Searches were conducted targeting English-language publications and congress proceedings of clinical trials and observational studies from January 1, 2012 to December 21, 2023 that reported effectiveness and safety outcomes (tumor response, progression-free survival (PFS), adverse events (AE)) for IRE and TACE. Two reviewers independently assessed eligibility and abstracted data. For each procedure, meta-analyses were conducted to assess tumor response by follow-up time point, as data permitted, and other outcomes were descriptively analyzed; Quality and risk of bias assessments were performed.

RESULTS

12 IRE publications (195 patients) and 33 TACE publications (6,899 patients) met eligibility criteria. During 0 to < 3 month follow-up, complete response was achieved in 84% of IRE patients vs. 68% for TACE (all results at 1-month); a proportion that increased at 3 to < 6 months (91% IRE vs. 41% TACE). Median PFS was 10.4 months for IRE and 19-30 months for TACE. Serious AEs (SAEs) were experienced by 4% vs. 5% of IRE and TACE patients, respectively.

CONCLUSION

Both IRE and TACE are safe and effective non-thermal treatments for unresectable, very early and early-stage HCC. The high rate of short-term complete response observed for IRE, coupled with a low SAE rate, may support the broader adoption of this procedure in this patient population.

Optimizing Treatment Selection for Early Hepatocellular Carcinoma Based on Tumor Biology, Liver Function, and Patient Status

Early-stage hepatocellular carcinoma (HCC) represents a critical window for curative treatment. However, treatment selection is complicated by significant heterogeneity in tumor biology, liver function, and patient performance status. This review provides a comprehensive overview of current curative-intent strategies for early-stage HCC, including liver transplantation, surgical resection, and local ablative therapies. We emphasize the importance of integrating tumor-specific characteristics-such as microvascular invasion, size, and anatomical location-with liver reserve metrics, including portal hypertension, Child-Pugh classification, and novel indices like albumin-bilirubin and albumin-indocyanine green evaluation grades. Furthermore, we discuss recent advances in non-thermal ablation techniques (eg, high-intensity focused ultrasound and irreversible electroporation), and technical innovations in radiofrequency ablation and cryoablation that are expanding the therapeutic landscape. By combining macro-level functional assessments with micro-level biological indicators, this review advocates for a personalized, evidence-based framework to optimize long-term outcomes in early HCC. The future of HCC management lies in standardizing individualized therapy.

Pulsed field ablation in medicine: irreversible electroporation and electropermeabilization theory and applications

BACKGROUND

Focal ablation techniques are integral in the surgical intervention of diseased tissue, where it is necessary to minimize damage to the surrounding parenchyma and critical structures. Irreversible electroporation (IRE) and high-frequency IRE (H-FIRE), colloquially called pulsed-field ablation (PFA), utilize high-amplitude, low-energy pulsed electric fields (PEFs) to nonthermally ablate soft tissue. PEFs induce cell death through permeabilization of the cellular membrane, leading to loss of homeostasis. The unique nonthermal nature of PFA allows for selective cell death while minimally affecting surrounding proteinaceous structures, permitting treatment near sensitive anatomy where thermal ablation or surgical resection is contraindicated. Further, PFA is being used to treat tissue when tumor margins are not expected after surgical resection, termed margin accentuation. This review explores both the theoretical foundations of PFA, detailing how PEFs induce cell membrane destabilization and selective tissue ablation, the outcomes following treatment, and its clinical implications across oncology and cardiology.

CONCLUSIONS

Clinical experience is still progressing, but reports have demonstrated that PFA reduces complications often seen with thermal ablation techniques. Mounting oncology data also support that PFA produces a robust immune response that may prevent local recurrences and attenuate metastatic disease. Despite promising outcomes, challenges such as optimizing field delivery and addressing variations in tissue response require further investigation. Future directions include refining PFA protocols and expanding its application to other therapeutic areas like benign tissue hyperplasia and chronic bronchitis.

The debate between electricity and heat, efficacy and safety of irreversible electroporation and radiofrequency ablation in the treatment of liver cancer: A meta-analysis

Both irreversible electroporation (IRE) and radiofrequency ablation (RFA) are viable ablation methods for localized treatment of liver tumors. We conducted a meta-analysis to access the efficacy and safety of IRE and RFA in liver cancer treatment. Clinical studies on IRE and RFA for the treatment of liver cancer were collected from PubMed and CNKI until June 2023. We screened the literature for ablation success rates at 1 month post-operation, extracting keywords such as "ablation success rate," "technical success rate," "recurrence rate," and "complication" for meta-analysis. A total of 37 articles were included: 24 related to RFA involving 1,685 cases and 13 related to IRE involving 524 cases. The results demonstrate that ablation success rates at post-operative 1 month for IRE and RFA were 86% (95% CI: 82-89%) and 87% (95% CI: 81-92%), respectively. Technical success rates were 96% (95% CI: 88-100%) and 99% (95% CI: 96-100%). In addition, the recurrence rate was 16% (95% CI: 12-22%) in RFA group and 16% (95% CI: 9-23%) in IRE group. In terms of safety, the RFA had a complication rate of 28% (95% CI: 10-50%) and the IRE had a rate of 26% (95% CI: 13-43%). In conclusion, IRE and RFA exhibit similar ablation success rates at 1 month post-operation and comparable complication rates, making them both safe and effective treatment options.

Advances in irreversible electroporation for prostate cancer

Irreversible electroporation is a nonthermal ablation technique that uses a high-voltage electric current to create nanosized pores in the cell membrane of a malignant tumor, thus resulting in cell death. In recent years, an increasing number of clinical studies have shown that irreversible electroporation is a safe and effective treatment for prostate cancer. We describe the progress of irreversible electroporation in prostate cancer in recent years in terms of its mechanism of action, clinical studies, advantages and disadvantages and summarize the gaps in existing studies and directions for future research.

Comparison of Chemotherapy Combined with Percutaneous Electroporation and Chemotherapy Alone in the Management of Locally Advanced Gallbladder Carcinoma (GBC): A Study Protocol

PURPOSE

This study aims to evaluate the feasibility and efficacy of chemotherapy combined with irreversible electroporation (IRE) in patients with locally advanced gallbladder carcinoma (GBC) presenting as gallbladder masses.

MATERIALS AND METHODS

Patients with unresectable GBC masses of size greater than 2 cm and less than 6 cm without evidence of distant metastases and with no contraindication to general anaesthesia will be enrolled in the study. They will be randomized using computer generated table into two arms with 1:1 allocation ratio to include 15 patients in each group. Group I will be the chemotherapy alone arm and Group II will be the combined image-guided irreversible electroporation of the tumour and chemotherapy arm. The primary outcome assessed shall be the clinical benefit rate (complete response, CR; partial response, PR and stable disease, SD) based on the mRECIST criteria and overall survival. The secondary outcome shall be feasibility and safety of the procedure and quality of life pre and post procedure. The quality of life will be assessed by a questionnaire as given by EORTC-Quality of Life Group before starting therapy and 4 weeks after completion of therapy.

EXPECTED GAIN OF KNOWLEDGE

The combined local and systemic effects of irreversible electroporation and systemic chemotherapy respectively may improve the outcomes in inoperable cases of gallbladder carcinoma.

TRIAL REGISTRATION

Clinical Trials Registry - India ( https://ctri.nic.in/Clinicaltrials/advancesearchmain.php ). Identifier: CTRI/2021/05/033803. Primary Register of the International Clinical Trials Registry Platform (WHO ICTRP) ( http://www.who.int/ictrp/search/en/ ).

Integrated Time Nanosecond Pulse Irreversible Electroporation (INSPIRE): Assessment of Dose, Temperature, and Voltage on Experimental and Clinical Treatment Outcomes

OBJECTIVE

This study sought to investigate a novel strategy using temperature-controlled delivery of nanosecond pulsed electric fields as an alternative to the 50-100 microsecond pulses used for irreversible electroporation.

METHODS

INSPIRE treatments were carried out at two temperatures in 3D tumor models using doses between 0.001 s and 0.1 s. The resulting treatment zones were quantified using viability staining and lethal electric field intensities were determined numerically. Computational modeling was then used to determine parameters necessary for INSPIRE treatments to achieve equivalent treatment zones to clinical electroporation treatments and evaluate the potential for these treatments to induce deleterious thermal damage.

RESULTS

Lethal thresholds between 1109 and 709 V/cm were found for nominal 0.01 s treatments with pulses between 350 ns and 2000 ns at physiological temperatures. Further increases in dose resulted in significant decreases in lethal thresholds. Given these experimental results, treatment zones comparable to clinical electroporation are possible by increasing the dose and voltage used with nanosecond duration pulses. Temperature-controlled simulations indicate minimal thermal cell death while achieving equivalent treatment volumes to clinical electroporation.

CONCLUSION

Nanosecond electrical pulses can achieve comparable outcomes to traditional electroporation provided sufficient electrical doses or voltages are applied. The use of temperature-controlled delivery may minimize thermal damage during treatment.

SIGNIFICANCE

Intense muscle stimulation and the need for cardiac gating have limited irreversible electroporation. Nanosecond pulses can alleviate these challenges, but traditionally have produced significantly smaller treatment zones. This study suggests that larger ablation volumes may be possible with the INSPIRE approach and that future in vivo studies are warranted.

Ultrasound-guided percutaneous high-frequency irreversible electroporation in porcine livers using four electrode needles: A feasibility and safety study

BACKGROUND

Malignant liver tumors seriously endanger human health. Among different therapeutic approaches, high-frequency irreversible electroporation (H-FIRE) is a recently emerging tumor ablation technique. The objective of this study was to evaluate the feasibility and safety of ultrasound-guided percutaneous H-FIRE using four electrode needles in porcine livers.

METHODS

Twelve experimental pigs underwent percutaneous H-FIRE ablation using a compound steep-pulse therapeutic device. Liver tissues adjacent to the gallbladder, blood vessels, and bile ducts were selected as the ablation targets. Pigs were randomly divided into three groups: (1) immediately after ablation (N = 4), (2) 2 days after ablation (N = 4), and (3) 7 days after ablation (N = 4). Blood routine, liver and kidney function, and myocardial enzyme levels were measured before and after ablation. Ultrasound, contrast-enhanced ultrasound (CEUS), contrast-enhanced magnetic resonance imaging (MRI), and hematoxylin-eosin staining were performed to evaluate the ablation performance.

RESULTS

Ultrasound-guided percutaneous H-FIRE ablations using four electrode needles were successfully performed in all 12 experimental pigs. The general conditions of the pigs, including postoperative activities and feeding behaviors, were normal, with no significant changes compared with the preoperative conditions. The imaging features of ultrasound, CEUS, and MRI demonstrated no significant changes in the gallbladder walls, bile ducts, or blood vessels close to the ablation areas. Laboratory tests showed that liver function indices and myocardial enzymes increased temporarily after H-FIRE ablation, but decreased to normal levels at 7 days after ablation. Histopathological examinations of porcine liver specimens showed that this technique could effectively ablate the target areas without damaging the surrounding or internal vascular systems and gallbladder.

CONCLUSIONS

This study demonstrated the feasibility and safety of ultrasound-guided percutaneous H-FIRE ablation in porcine livers in vivo, and proposed a four-needle method to optimize its clinical application.

The Emerging Landscape for Combating Resistance Associated with Energy-Based Therapies via Nanomedicine

Cancer represents a serious disease with significant implications for public health, imposing substantial economic burden and negative societal consequences. Compared to conventional cancer treatments, such as surgery and chemotherapy, energy-based therapies (ET) based on athermal and thermal ablation provide distinct advantages, including minimally invasive procedures and rapid postoperative recovery. Nevertheless, due to the complex pathophysiology of many solid tumors, the therapeutic effectiveness of ET is often limited. Nanotechnology offers unique opportunities by enabling facile material designs, tunable physicochemical properties, and excellent biocompatibility, thereby further augmenting the outcomes of ET. Numerous nanomaterials have demonstrated the ability to overcome intrinsic therapeutic resistance associated with ET, leading to improved antitumor responses. This comprehensive review systematically summarizes the underlying mechanisms of ET-associated resistance (ETR) and highlights representative applications of nanoplatforms used to mitigate ETR. Overall, this review emphasizes the recent advances in the field and presents a detailed account of novel nanomaterial designs in combating ETR, along with efforts aimed at facilitating their clinical translation.

Irreversible Electroporation of the Hepatobiliary System: Current Utilization and Future Avenues

Liver cancer remains a leading cause of cancer-related deaths worldwide despite numerous advances in treatment. While surgical resection remains the gold standard for curative treatment, it is only possible for a minority of patients. Thermal ablation is an effective option for the treatment of smaller tumors; however, its use is limited to tumors that are not located in proximity to sensitive structures due to the heat sink effect and the potential of thermal damage. Irreversible electroporation (IRE) is a non-thermal ablative modality that can deliver targeted treatment and the effective destruction of tumors that are in close proximity to or even surrounding vascular or biliary ducts with minimal damage to these structures. IRE produces short pulses of high-frequency energy which opens pores in the lipid bilayer of cells leading to apoptosis and cell death. IRE has been utilized clinically for over a decade in the treatment of liver cancers with multiple studies documenting an acceptable safety profile and high efficacy rates.

Irreversible electroporation of hepatocellular carcinoma and colorectal cancer liver metastases: A nationwide multicenter study with short- and long-term follow-up

INTRODUCTION

A nationwide multicenter study was performed to examine short- and long-term effects of irreversible electroporation (IRE) for hepatocellular carcinoma (HCC) and colorectal cancer liver metastases (CRCLM). IRE is an alternative method when thermal ablation is contraindicated because of risk for serious thermal complications.

METHODS

All consecutive patients in Sweden treated with IRE because of HCC or CRCLM, were included between 2011 and 2018. We evaluated medical records and radiological imaging to obtain information regarding patient-, tumor-, and treatment characteristics. We also assessed local tumor progression, and survival.

RESULTS

In total 206 tumors in 149 patients were treated with IRE. Eighty-seven patients (58.4%) had colorectal cancer liver metastases, and 62 patients (41.6%) had hepatocellular carcinoma. Median tumor size was 20 mm (i.q.r. 14-26 mm). Median overall survival for CRCLM and HCC, were 27.0 months (95% CI 22.2-31.8 months), and 35.0 months (95% CI 13.8-56.2 months), respectively. Median follow-up time was 58 months (95% CI 50.6-65.4). Local ablation success at six and twelve months for HCC was 58.3% and 40.3%, and for CRCLM 37.7% and 25.4%. The median time to local tumor progression (LTP) for HCC was 21.0 months (95% CI: 9.5-32.5 months), and for CRCLM 6.0 months (95% CI: 4.5-7.5 months). At 30-day follow-up, 15.4% (n = 23) of patients suffered from a complication rated as Clavien-Dindo grade 1-3a. Three patients (2.0%) had grade 3b-5 with one death in a thromboembolic event.

CONCLUSION

IRE is a safe ablation modality for patients with liver tumors that are located in such a way that other treatment options are unsuitable.

Clinical consensus statement: Establishing the roles of locoregional and systemic therapies for the treatment of intermediate-stage hepatocellular carcinoma in Canada

BACKGROUND

Hepatocellular carcinoma (HCC) a leading cause of cancer mortality worldwide and approximately one-third of patients present with intermediate-stage disease. The treatment landscape of intermediate-stage HCC is rapidly evolving due to developments in local, locoregional and systemic therapies. Treatment recommendations focused on this heterogenous disease stage and that take into account the Canadian reality are lacking. To address this gap, a pan-Canadian group of experts in hepatology, transplant, surgery, radiation therapy, nuclear medicine, interventional radiology, and medical oncology came together to develop consensus recommendations on management of intermediate-stage HCC relevant to the Canadian context.

METHODS

A modified Delphi framework was used to develop consensus statements with strengths of recommendation and supporting levels of evidence graded using the AHA/ACC classification system. Tentative consensus statements were drafted based on a systematic search and expert input in a series of iterative feedback cycles and were then circulated via online survey to assess the level of agreement.

RESULTS & CONCLUSION

The pre-defined ratification threshold of 80 % agreement was reached for all statements in the areas of multidisciplinary treatment (n = 4), intra-arterial therapy (n = 14), biologics (n = 5), radiation therapy (n = 3), surgical resection and transplantation (n = 7), and percutaneous ablative therapy (n = 4). These generally reflected an expansion in treatment options due to developments in previously established or emergent techniques, introduction of new and more active therapies and increased therapeutic flexibility. These developments have allowed for greater treatment tailoring and personalization as well as a paradigm shift toward strategies with curative intent in a wider range of disease settings.

Advances of Electroporation-Related Therapies and the Synergy with Immunotherapy in Cancer Treatment

Electroporation is the process of instantaneously increasing the permeability of a cell membrane under a pulsed electric field. Depending on the parameters of the electric pulses and the target cell electrophysiological characteristics, electroporation can be either reversible or irreversible. Reversible electroporation facilitates the delivery of functional genetic materials or drugs to target cells, inducing cell death by apoptosis, mitotic catastrophe, or pseudoapoptosis; irreversible electroporation is an ablative technology which directly ablates a large amount of tissue without causing harmful thermal effects; electrotherapy using an electric field can induce cell apoptosis without any aggressive invasion. Reversible and irreversible electroporation can also activate systemic antitumor immune response and enhance the efficacy of immunotherapy. In this review, we discuss recent progress related to electroporation, and summarize its latest applications. Further, we discuss the synergistic effects of electroporation-related therapies and immunotherapy. We also propose perspectives for further investigating electroporation and immunotherapy in cancer treatment.

Irreversible electroporation and electrochemotherapy in oncology: State of the art

Thermal tumor ablation techniques including radiofrequency, microwave, LASER, high-intensity focused ultrasound and cryoablation are routinely used to treated liver, kidney, bone, or lung tumors. However, all these techniques are thermal and can therefore be affected by heat sink effect, which can lead to incomplete ablation, and thermal injuries of non-targeted tissues are possible. Under certain conditions, high voltage pulsed electric field can induce formation of pores in the cell membrane. This phenomenon, called electropermeabilization, is also known as "electroporation". Under certain conditions, electroporation can be irreversible, leading to cell death. Irreversible electroporation has demonstrated efficacy for the treatment of liver and prostate cancers, whereas data are scarce regarding pancreatic and renal cancers. During reversible electroporation, transient cell permeability can be used to introduce cytotoxic drugs into tumor cells (commonly bleomycin or cisplatin). Reversible electroporation used in conjunction with cytotoxic drugs shows promise in terms of oncological response, particularly for solid cutaneous and subcutaneous tumors such as melanoma. Irreversible and reversible electroporation are both not thermal ablation techniques and therefore open a new promising horizon for tumor ablation.

Emerging nanobiotechnology for precise theranostics of hepatocellular carcinoma

Primary liver cancer has become the second most fatal cancer in the world, and its five-year survival rate is only 10%. Most patients are in the middle and advanced stages at the time of diagnosis, losing the opportunity for radical treatment. Liver cancer is not sensitive to chemotherapy or radiotherapy. At present, conventional molecularly targeted drugs for liver cancer show some problems, such as short residence time, poor drug enrichment, and drug resistance. Therefore, developing new diagnosis and treatment methods to effectively improve the diagnosis, treatment, and long-term prognosis of liver cancer is urgent. As an emerging discipline, nanobiotechnology, based on safe, stable, and efficient nanomaterials, constructs highly targeted nanocarriers according to the unique characteristics of tumors and further derives a variety of efficient diagnosis and treatment methods based on this transport system, providing a new method for the accurate diagnosis and treatment of liver cancer. This paper aims to summarize the latest progress in this field according to existing research and the latest clinical diagnosis and treatment guidelines in hepatocellular carcinoma (HCC), as well as clarify the role, application limitations, and prospects of research on nanomaterials and the development and application of nanotechnology in the diagnosis and treatment of HCC.

An overview of the irreversible electroporation for the treatment of liver metastases: When to use it

Tumour ablation is an established therapy for local treatment of liver metastases and hepatocellular carcinoma. Most commonly two different kind of thermic ablation, radiofrequency ablation and microwave ablation, are used in clinical practice. The aim of both is to induce thermic damage to the malignant cells in order to obtain coagulative necrosis of the neoplastic lesions. Our main concerns about these procedures are the collateral thermic damage to adjacent structures and heat-sink effect. Irreversible electroporation (IRE) is a recently developed, non-thermal ablation procedure which works applying short pulses of direct current that generate an electric field in the lesion area. The electric field increase the transmembrane potential, changing its permeability to ions.Irreversible electroporation does not generate heat, giving the chance to avoid the heat-sink effect and opening the path to a better treatment of all the lesions located in close proximity to big vessels and bile ducts. Electric fields produced by the IRE may affect endothelial cells and cholangiocytes but they spare the collagen matrix, preserving re-epithelization process as well as the function of the damaged structures. Purpose of the authors is to identify the different scenarios where CT-guided percutaneous IRE of the liver should be preferred to other ablative techniques and why.

Recent Perspectives on the Mechanism of Recurrence After Ablation of Hepatocellular Carcinoma: A Mini-Review

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Hepatectomy, liver transplantation, and ablation are the three radical treatments for early-stage hepatocellular carcinoma (ESHCC), but not all patients are fit for or can tolerate surgery; moreover, liver donors are limited. Therefore, ablation plays an important role in the treatment of ESHCC. However, some studies have shown that ablation has a higher local recurrence (LR) rate than hepatectomy and liver transplantation. The specific mechanism is unknown. The latest perspectives on the mechanism of recurrence after ablation of HCC were described and summarized. In this review, we discussed the possible mechanisms of recurrence after ablation of HCC, including epithelial–mesenchymal transition (EMT), activating autophagy, changes in non-coding RNA, and changes in the tumor microenvironment. A systematic and comprehensive understanding of the mechanism will contribute to the research and development of related treatment, combined with ablation to improve the therapeutic effect in patients with ESHCC.

The Safety and Efficacy of Nanosecond Pulsed Electric Field in Patients With Hepatocellular Carcinoma: A Prospective Phase 1 Clinical Study Protocol

BACKGROUND

Hepatocellular carcinoma (HCC) is a highly aggressive malignancy. Irreversible electroporation (IRE) is an ablative modality that uses high-voltage electrical pulses to permeabilize the cell membrane leading to cell necrosis. Unlike traditional thermal ablation, IRE is hardly affected by the "heat-sink" effect and can prevent damage of the adjacent vital structures. Nanosecond pulsed electric field (nsPEF) is a new IRE technique using ultra-short pulses (nanosecond duration), can not only penetrate the cell membranes, but also act on the organelles. Sufficient preclinical researches have shown that nsPEF can eliminate HCC without damaging vital organs, and elicit potent anti-tumor immune response.

OBJECTIVE

This is the first clinical study to evaluate feasibility, efficacy, and safety of nsPEF for the treatment of HCC, where thermal ablation is unsuitable due to proximity to critical structures.

METHODS AND ANALYSIS

We will conduct an open-labeled, single-arm, prospective, multicenter, and objective performance criteria trial. One hundred and ninety-two patients with HCC, in which the tumor is located immediately (<0.5 cm) adjacent to the portal vein, hepatic veins, bile duct, gastrointestinal tract, or diaphragm, will be enrolled among 4 academic medical centers. The primary outcomes are the rate of complete ablation at 1 month and adverse events. Secondary outcomes include technical success, technique efficacy, nsPEF procedural characteristics, local tumor progression, and local progression-free survival.

ETHICS AND DISSEMINATION

The trial will be conducted according to the ethical principles of the Declaration of Helsinki and has been approved by the ethics committee of all participating centers. The results of this study will be published in peer-reviewed scientific journals and presented at relevant academic conferences.

CONCLUSIONS

This study is the Phase 1 clinical trial to evaluate the efficacy and safety of nsPEF in patients with HCC at high-risk locations where thermal ablation is contra-indicated. The results may expand the options and offer an alternative therapy for HCC.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier NCT04309747.

High-Frequency Irreversible Electroporation (H-FIRE) Induced Blood-Brain Barrier Disruption Is Mediated by Cytoskeletal Remodeling and Changes in Tight Junction Protein Regulation

Glioblastoma is the deadliest malignant brain tumor. Its location behind the blood-brain barrier (BBB) presents a therapeutic challenge by preventing effective delivery of most chemotherapeutics. H-FIRE is a novel tumor ablation method that transiently disrupts the BBB through currently unknown mechanisms. We hypothesized that H-FIRE mediated BBB disruption (BBBD) occurs via cytoskeletal remodeling and alterations in tight junction (TJ) protein regulation. Intracranial H-FIRE was delivered to Fischer rats prior to sacrifice at 1-, 24-, 48-, 72-, and 96 h post-treatment. Cytoskeletal proteins and native and ubiquitinated TJ proteins (TJP) were evaluated using immunoprecipitation, Western blotting, and gene-expression arrays on treated and sham control brain lysates. Cytoskeletal and TJ protein expression were further evaluated with immunofluorescent microscopy. A decrease in the F/G-actin ratio, decreased TJP concentrations, and increased ubiquitination of TJP were observed 1-48 h post-H-FIRE compared to sham controls. By 72-96 h, cytoskeletal and TJP expression recovered to pretreatment levels, temporally corresponding with increased claudin-5 and zonula occludens-1 gene expression. Ingenuity pathway analysis revealed significant dysregulation of claudin genes, centered around claudin-6 in H-FIRE treated rats. In conclusion, H-FIRE is capable of permeating the BBB in a spatiotemporal manner via cytoskeletal-mediated TJP modulation. This minimally invasive technology presents with applications for localized and long-lived enhanced intracranial drug delivery.

Irreversible electroporation versus radiofrequency ablation for malignant hepatic tumor: A prospective single-center double-arm trial

Objective

Irreversible electroporation (IRE) is a nonthermal ablation technique for the treatment of malignant liver tumors. IRE has demonstrated efficacy and safety in the treatment of malignant liver tumors and its unique advantages in the treatment of nearby vascular lesions. This study aimed to compare the efficacy, safety, and intermediate-term outcomes of IRE and radiofrequency (RF) therapy in malignant liver tumors.

Methods

Twenty-four patients with primary or secondary liver malignancies were included in this prospective, double-arm clinical trial. Patients were randomly divided into the IRE and RF groups. The primary outcome was the efficacy (local ablation control evaluation at 90 days). The secondary outcomes were safety (procedure-related complications at ​≤ ​90 days) and intermediate-term survival (at 24 months).

Results

The ablation assessment at 90 days after surgery with mRECIST for IRE versus RF were 70%, 20%, 0%, and 10% versus 92.9%, 7.1%, 0%, and 0% (CR, PR, SD, and PD, respectively). The complication rates of IRE versus RF with Clavien-Dindo classification were 16.7%, 25%, 0%, 8.3%, and 8.3% versus 8.3%, 50%, 0%, 0%, and 0% (Grade I, II, III, IV, and V, respectively). The average overall survival (OS) was 17.55 months in the IRE group (95% CI 15.13-22.37) and 18.75 months in the RF group (95% CI 12.48-22.61). There was no statistical difference between the IRE and RF groups in terms of efficacy (p ​= ​0.48), safety(p ​= ​0.887), or 24-month OS (p ​= ​0.959).

Conclusions

IRE ablation revealed similar efficacy and safety in a short-term follow-up, and similar OS in mid-term survival as RF ablation in treating malignant hepatic tumors.

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A prospective single-center double-arm clinical trial of IRE/RF.

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Study compared efficacy, safety in short-term and intermediate-term overall survival of IRE and RF in liver malignant tumors.

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All procedures were performed with CT-guided percutaneous ablation..

Modeling of a single bipolar electrode with tines for irreversible electroporation delivery

Irreversible electroporation (IRE) is a non-thermal tumor ablation technology employed to treat solid tumors not amenable to resection or thermal ablation. The IRE systems currently in clinical use deliver electrical pulses via multiple monopolar electrodes. This approach can present significant technical challenges due to the requirement for accurate placement of multiple electrodes and maintenance of parallel electrode alignment during pulse delivery. In this study, we sought to evaluate a novel IRE electrode configuration consisting of a single bipolar electrode with deployable tines. Using commercial finite element software predicted ablation outcomes, thermal damage, ablation sphericity, and energy delivery were calculated for existing monopolar and bipolar electrodes, and bipolar electrodes with either 4 or 8 deployable tines. The bipolar electrodes with tines generated larger predicted ablations compared to existing monopolar (>100%) and bipolar (>10%) arrangements, and the ablation shape using bipolar electrodes with tines were more spherical than those modeled for bipolar electrodes. Thermal damage modeled for bipolar electrodes and bipolar electrodes with tines was less than that of monopolar electrodes (using identical pulse parameters), and bipolar electrodes with tines delivered less energy than monopolar or bipolar electrodes. These studies using a single point of device insertion suggest the potential for developing alternative IRE delivery techniques, and may simplify clinical use and increase the predicted ablation shape/volume.

Irreversible Electroporation: An Emerging Immunomodulatory Therapy on Solid Tumors

Irreversible electroporation (IRE), a novel non-thermal ablation technique, is utilized to ablate unresectable solid tumors and demonstrates favorable safety and efficacy in the clinic. IRE applies electric pulses to alter the cell transmembrane voltage and causes nanometer-sized membrane defects or pores in the cells, which leads to loss of cell homeostasis and ultimately results in cell death. The major drawbacks of IRE are incomplete ablation and susceptibility to recurrence, which limit its clinical application. Recent studies have shown that IRE promotes the massive release of intracellular concealed tumor antigens that become an "in-situ tumor vaccine," inducing a potential antitumor immune response to kill residual tumor cells after ablation and inhibiting local recurrence and distant metastasis. Therefore, IRE can be regarded as a potential immunomodulatory therapy, and combined with immunotherapy, it can exhibit synergistic treatment effects on malignant tumors, which provides broad application prospects for tumor treatment. This work reviewed the current status of the clinical efficacy of IRE in tumor treatment, summarized the characteristics of local and systemic immune responses induced by IRE in tumor-bearing organisms, and analyzed the specific mechanisms of the IRE-induced immune response. Moreover, we reviewed the current research progress of IRE combined with immunotherapy in the treatment of solid tumors. Based on the findings, we present deficiencies of current preclinical studies of animal models and analyze possible reasons and solutions. We also propose possible demands for clinical research. This review aimed to provide theoretical and practical guidance for the combination of IRE with immunotherapy in the treatment of malignant tumors.

Irreversible electroporation for liver cancer ablation: A meta analysis

OBJECTIVE

To evaluate the efficacy and safety of IRE in the treatment of hepatic malignant tumors, especially the damage to the gastrointestinal tract, bile ducts, and vital vessels.

METHODS

The relevant literatures published from January 1, 2010 to July 1, 2021 were searched from PubMed and Embase databases. The following keywords were applied: "irreversible electroporation", "IRE", "unresectable Hepa∗ cancer", "ablation" and "ablation therapy".

RESULTS

Twenty-six studies were identified covering 807 participants and 1115 lesions. The complete ablation rate of liver cancer by IRE was 86% (95% CI: 81%-90%). The incidence of IRE-related complications was 23% (95% CI: 17%-28%), but most of them were minor, major complications such as biliary fistula, intestinal fistula and massive hemorrhage were rare.

CONCLUSION

Meta-analysis showed that IRE ablation is safe and effective for liver cancer treatment. Bile duct, intestine and blood vessels adjacent to the tumors are rarely damaged by IRE ablation.

Image-guided locoregional non-intravascular interventional treatments for hepatocellular carcinoma: Current status

Hepatocellular carcinoma (HCC) is one of the most deadly and frequent cancers worldwide, although great advancement in the treatment of this malignancy have been made within the past few decades. It continues to be a major health issue due to an increasing incidence and a poor prognosis. The majority of patients have their HCC diagnosed at an intermediate or advanced stage in theUSA or China. Curative therapy such as surgical resection or liver transplantation is not considered anoption of treatment at these stages.

Transarterial chemoembolization (TACE), the most widely used locoregional therapeutic approach, used to be the mainstay of treatment for cases with unresectable cancer entities. However, for those patients with hypovascular tumors or impaired liver function reserve, TACE is a suboptimal treatment option. For example, embolization does not result in complete coverage of a hypovascular tumor, and may rather promotes postoperative tumor recurrence, or leave residual tumor, in these TACE-resistance patients. In addition, TACE carries a higher risk of hepatic decompensation in patients with poor liver function or reserve.

Non-vascular interventional locoregional therapies for HCC include radiofrequency ablation (RFA), microwave ablation (MWA), high-intensity focused ultrasound (HIFU), laser-induced thermotherapy (LITT), cryosurgical ablation (CSA), irreversible Electroporation (IRE), percutaneous ethanol injection (PEI), and brachytherapy. Recent advancements in these techniques have significantly improved the treatment efficacy of HCC and expanded the population of patients who qualify for treatment. This review embraces the current status of imaging-guided locoregional non-intravascular interventional treatments for HCCs, with a primary focus on the clinical evaluation and assessment of the efficacy of combined therapies using these interventional techniques.

Chemotherapy plus concurrent irreversible electroporation improved local tumor control in unresectable hilar cholangiocarcinoma compared with chemotherapy alone

INTRODUCTION

Unresectable hilar cholangiocarcinoma (UHC) is a malignant tumor and has a poor prognosis. IRE is a novel non-thermal ablative therapy that causes cellular apoptosis via electrical impulses. To compare the curative effect for UHC, chemotherapy plus concurrent IRE and chemotherapy alone were set up.

MATERIALS AND METHODS

From July 2015 to May 2019, 47 patients with UHC were analyzed to chemotherapy + IRE group (n = 23) or chemotherapy alone group (n = 24) in this study. Treatment response was assessed with computed tomography (CT) or magnetic resonance imaging (MRI) 1 month after treatment and every 3 months thereafter. Local tumor progression (LTP), time to LTP, overall survival (OS) and procedure-related complications were compared between the two groups.

RESULTS

Chemotherapy plus concurrent IRE group showed a tendency toward a decreased rate of LTP (16.7% vs. 39.5%; p = 0.039) and an increased complete response rate (52.2% vs. 12.5%; p = 0.011) compared with chemotherapy alone group. Time to LTP was significantly longer in the chemotherapy plus concurrent IRE group compared to chemotherapy alone group (11.2 months vs. 4.2 months; p = 0.001). Median OS was significantly longer in the chemotherapy plus concurrent IRE group compared to chemotherapy alone group (19.6 months vs. 10.2 months; p = 0.001).

CONCLUSIONS

Chemotherapy plus concurrent IRE improved local control and prolonged time to LTP and OS in patients with UHC.

Engineering nanotheranostic strategies for liver cancer

The incidence and mortality of hepatocellular carcinoma have continued to increase over the last few years, and the medicine-based outlook of patients is poor. Given great ideas from the development of nanotechnology in medicine, especially the advantages in the treatments of liver cancer. Some engineering nanoparticles with active targeting, ligand modification, and passive targeting capacity achieve efficient drug delivery to tumor cells. In addition, the behavior of drug release is also applied to the drug loading nanosystem based on the tumor microenvironment. Considering clinical use of local treatment of liver cancer, in situ drug delivery of nanogels is also fully studied in orthotopic chemotherapy, radiotherapy, and ablation therapy. Furthermore, novel therapies including gene therapy, phototherapy, and immunotherapy are also applied as combined therapy for liver cancer. Engineering nonviral polymers to function as gene delivery vectors with increased efficiency and specificity, and strategies of co-delivery of therapeutic genes and drugs show great therapeutic effect against liver tumors, including drug-resistant tumors. Phototherapy is also applied in surgical procedures, chemotherapy, and immunotherapy. Combination strategies significantly enhance therapeutic effects and decrease side effects. Overall, the application of nanotechnology could bring a revolutionary change to the current treatment of liver cancer.

Efficacy and safety of irreversible electroporation for malignant liver tumors: a systematic review and meta-analysis

OBJECTIVE

The data regarding overall survival (OS) and progression-free survival (PFS) following irreversible electroporation (IRE) is scarce. We performed a systematic review of the safety and efficacy of IRE for liver malignancies.

METHODS

Searches of MEDLINE, EMBASE, and SCOPUS databases were performed through September 1, 2019. Studies reporting the survival data (OS and PFS) and complications (graded according to the Society of interventional Radiology classification) were included. A generalized linear mixed method with a random-effects model was used for assessing pooled incidence rates and corresponding 95% confidence intervals (CIs).

RESULTS

A total of 25 studies (n = 776, 15 prospective, 10 retrospective) were included. Metastasis, hepatocellular carcinoma, and cholangiocarcinoma were present in 354, 285, and 100 patients, respectively. The pooled OS at 6, 12, 24, and 36 months was 93.28% (95% CI: 63.23-99.12, I2= 67%), 81.29% (95% CI: 69.80-89.22, I2 = 73%), 61.47% (95% CI: 52.81-69.46, I2 = 0%), and 40.88% (95% CI: 28.43-54.61, I2 = 64%), respectively. The pooled PFS at 6, 12, and 24 months was 79.72% (95% CI: 67.88-87.97, I2 = 70%), 64.19% (95% CI: 56.68-71.06, I2 = 57%), 49.05% (95% CI: 11.47-87.73, I2 = 96%), respectively. Overall complication rate was 23.7%. Major complications (grade C-F) occurred in 6.9% patients.

CONCLUSION

IRE is associated with favorable OS and PFS. Although the overall complication rate is high, most complications are graded as minor.

KEY POINTS

• The pooled OS and PFS at 6, 12, and 24 months for all the tumor types was 93.28% and 79.72%, 81.29% and 64.19%, and 61.47% and 49.05%, respectively. • HCC was associated with a better OS at 12 and 36 months. • The overall complication rate was 23.7%, with major complications (SIR grade C-F) comprising 6.9%.

Image-Guided Peri-Tumoral Radiofrequency Hyperthermia-Enhanced Direct Chemo-Destruction of Hepatic Tumor Margins

Purpose

To validate the feasibility of using peri-tumoral radiofrequency hyperthermia (RFH)-enhanced chemotherapy to obliterate hepatic tumor margins.

Method and Materials

This study included in vitro experiments with VX2 tumor cells and in vivo validation experiments using rabbit models of liver VX2 tumors. Both in vitro and in vivo experiments received different treatments in four groups (n=6/group): (i) RFH-enhanced chemotherapy consisting of peri-tumoral injection of doxorubicin plus RFH at 42°C; (ii) RFH alone; (iii) doxorubicin alone; and (iv) saline. Therapeutic effect on cells was evaluated using different laboratory examinations. For in vivo experiments, orthotopic hepatic VX2 tumors in 24 rabbits were treated by using a multipolar radiofrequency ablation electrode, enabling simultaneous delivery of both doxorubicin and RFH within the tumor margins. Ultrasound imaging was used to follow tumor growth overtime, correlated with subsequent histopathological analysis.

Results

In in vitro experiments, MTS assay demonstrated the lowest cell proliferation, and apoptosis analysis showed the highest apoptotic index with RFH-enhanced chemotherapy, compared with the other three groups (p<0.01). In in vivo experiments, ultrasound imaging detected the smallest relative tumor volume with RFH-enhanced chemotherapy (p<0.01). The TUNEL assay further confirmed the significantly increased apoptotic index and decreased cell proliferation in the RFH-enhanced therapy group (p<0.01).

Conclusion

This study demonstrates that peri-tumoral RFH can specifically enhance the destruction of tumor margins in combination with peri-tumoral injection of a chemotherapeutic agent. This new interventional oncology technique may address the critical clinical problem of frequent marginal tumor recurrence/persistence following thermal ablation of large (>3 cm) hepatic cancers.

Combination of irreversible electroporation with sustained release of a synthetic membranolytic polymer for enhanced cancer cell killing

Irreversible electroporation (IRE) is used clinically as a focal therapy to ablate solid tumors. A critical disadvantage of IRE as a monotherapy for cancer is the inability of ablating large tumors, because the electric field strength required is often too high to be safe. Previous reports indicate that cells exposed to certain cationic small molecules and surfactants are more vulnerable to IRE at lower electric field strengths. However, low-molecular-weight IRE sensitizers may suffer from suboptimal bioavailability due to poor stability and a lack of control over spatiotemporal accumulation in the tumor tissue. Here, we show that a synthetic membranolytic polymer, poly(6-aminohexyl methacrylate) (PAHM), synergizes with IRE to achieve enhanced cancer cell killing. The enhanced efficacy of the combination therapy is attributed to PAHM-mediated sensitization of cancer cells to IRE and to the direct cell killing by PAHM through membrane lysis. We further demonstrate sustained release of PAHM from embolic beads over 1 week in physiological medium. Taken together, combining IRE and a synthetic macromolecular sensitizer with intrinsic membranolytic activity and sustained bioavailability may present new therapeutic opportunities for a wide range of solid tumors.

Intratumoral STING Agonist Injection Combined with Irreversible Electroporation Delays Tumor Growth in a Model of Hepatocarcinoma

BACKGROUND/AIM

Irreversible electroporation (IRE) showed promising results for small-size tumors and very early cancers. However, further development is needed to evolve this procedure into a more efficient ablation technique for long-term control of tumor growth. In this work, we show that it is possible to increase the antitumor efficiency of IRE by simmultaneously injecting c-di-GMP, a STING agonist, intratumorally.

MATERIALS AND METHODS

Intratumoral administration of c-di-GMP simultaneously to IRE was evaluated in murine models of melanona (B16.OVA) and hepatocellular carcinoma (PM299L).

RESULTS

The combined therapy increased the number of tumor-infiltrating IFN-γ/TNF-α-producing CD4 and CD8 T cells and delayed tumor growth, as compared to the effect observed in groups treated with c-di-GMP or IRE alone.

CONCLUSION

These results can lead to the development of a new therapeutic strategy for the treatment of cancer patients refractory to other therapies.

Thermochromic Tissue Phantoms for Evaluating Temperature Distribution in Simulated Clinical Applications of Pulsed Electric Field Therapies

Background: Irreversible electroporation (IRE) induces cell death through nonthermal mechanisms, however, in extreme cases, the treatments can induce deleterious thermal transients. This study utilizes a thermochromic tissue phantom to enable visualization of regions exposed to temperatures above 60°C. Materials and Methods: Poly(vinyl alcohol) hydrogels supplemented with thermochromic ink were characterized and processed to match the electrical properties of liver tissue. Three thousand volt high-frequency IRE protocols were administered with delivery rates of 100 and 200 μs/s. The effect of supplemental internal applicator cooling was then characterized. Results: Baseline treatments resulted thermal areas of 0.73 cm2, which decreased to 0.05 cm2 with electrode cooling. Increased delivery rates (200 μs/s) resulted in thermal areas of 1.5 and 0.6 cm2 without and with cooling, respectively. Conclusions: Thermochromic tissue phantoms enable rapid characterization of thermal effects associated with pulsed electric field treatments. Active cooling of applicators can significantly reduce the quantity of tissue exposed to deleterious temperatures.

Electroporation as the Immunotherapy Strategy for Cancer in Veterinary Medicine: State of the Art in Latin America

Electroporation is a technology that increases cell membrane permeability by the application of electric pulses. Electrochemotherapy (ECT), the best-known application of electroporation, is a very effective local treatment for tumors of any histology in human and veterinary medicine. It induces a local yet robust immune response that is responsible for its high effectiveness. Gene electrotransfer (GET), used in research to produce a systemic immune response against cancer, is another electroporation-based treatment that is very appealing for its effectiveness, low cost, and simplicity. In this review, we present the immune effect of electroporation-based treatments and analyze the results of the vast majority of the published papers related to immune response enhancement by gene electrotransfer in companion animals with spontaneous tumors. In addition, we present a brief history of the initial steps and the state of the art of the electroporation-based treatments in Latin America. They have the potential to become an essential form of immunotherapy in the region. This review gives insight into the subject and helps to choose promising research lines for future work; it also helps to select the adequate treatment parameters for performing a successful application of this technology.

Effectiveness and safety of irreversible electroporation for recurrent hepatocellular carcinoma ineligible for thermal ablation after surgery

Objectives

To preliminarily evaluate the clinical effectiveness and safety of computed tomography (CT) image-guided irreversible electroporation (IRE) for the treatment of recurrent hepatocellular carcinoma (HCC) after surgical resection.

Methods

From January 2016 to February 2018, 18 patients diagnosed with recurrent HCC after surgical resection received IRE under CT image guidance for 22 tumors. Patients were enrolled for IRE when ineligible for thermal ablation due to tumor location. Clinical records and imaging data were reviewed to assess complete ablation rate, local tumor progression free rate (LTPFR), local tumor progression free survival (LTPFS) and complications after a median follow-up time of 14 months.

Results

Successful complete ablations were achieved in 20/22 (90.1%) tumors. Mean LTPFS was 10.5 ​± ​9.4 months. Overall 3-, 6- and 12-months LTPFR in 22 tumors following IRE were 68.2% (95% confidence interval [CI]: 45%–83%), 59.1% (95% CI: 33%–76%) and 36.4% (95% CI: 17%–56%), respectively. Complications included pneumothorax (2/18, 11.1%), localized pain (3/18, 16.7%), bile duct dilation (1/18, 5.6%) and transient hypertension (1/18, 5.6%). No major complications or treatment-related deaths were observed. The alpha-fetoprotein levels of two patients decreased to the normal range at 3 and 4 months, respectively.

Conclusions

This study showed that percutaneous CT image-guided IRE can serve as a safe and effective treatment for recurrent HCC not suitable for thermal ablation.

Electro-Thermal Therapy Algorithms and Active Internal Electrode Cooling Reduce Thermal Injury in High Frequency Pulsed Electric Field Cancer Therapies

Thermal tissue injury is an unintended consequence in current irreversible electroporation treatments due to the induction of Joule heating during the delivery of high voltage pulsed electric fields. In this study active temperature control measures including internal electrode cooling and dynamic energy delivery were investigated as a process for mitigating thermal injury during treatment. Ex vivo liver was used to examine the extent of thermal injury induced by 5000 V treatments with delivery rates up to five times faster than current clinical practice. Active internal cooling of the electrode resulted in a 36% decrease in peak temperature vs. non-cooled control treatments. A temperature based feedback algorithm (electro-thermal therapy) was demonstrated as capable of maintaining steady state tissue temperatures between 30 and 80 °C with and without internal electrode cooling. Thermal injury volumes of 2.6 cm³ were observed for protocols with 60 °C temperature set points and electrode cooling. This volume reduced to 1.5 and 0.1 cm³ for equivalent treatments with 50 °C and 40 °C set points. Finally, it was demonstrated that the addition of internal electrode cooling and active temperature control algorithms reduced ETT treatment times by 84% (from 343 to 54 s) vs. non-cooled temperature control strategies with equivalent thermal injury volumes.

Electro-thermal therapy: Microsecond duration pulsed electric field tissue ablation with dynamic temperature control algorithms

Electro-thermal therapy (ETT) is a new cancer treatment modality which combines the use of high voltage pulsed electric fields, dynamic energy delivery rates, and closed loop thermal control algorithms to rapidly and reproducibly create focal ablations. This study examines the ablative potential and profile of pulsed electric field treatments delivered in conjunction with precise temperature control algorithms. An ex vivo perfused liver model was utilized to demonstrate the capability of 5000 V 2 μs duration bipolar electrical pulses and dynamic temperature control algorithms to produce ablations. Using a three applicator array, 4 cm ablation zones were created in under 27 min. In this configuration, the algorithms were able to rapidly achieve and maintain temperatures of 80 °C at the tissue-electrode interface. A simplified single applicator and grounding pad approach was used to correlate the measured ablation zones to electric field isocontours in order to determine lethal electric field thresholds of 708 V/cm and 867 V/cm for 45 °C and 60 °C treatments, respectively. These results establish ETT as a viable method for hepatic tumor treatment with ablation profiles equivalent to other energy based techniques. The single applicator and multi-applicator approaches demonstrated may enable the treatment of complex tumor geometries. The flexibility of ETT temperature control yields a malleable intervention which gives clinicians robust control over the ablation modality, treatment time, and safety profile.

High-Voltage Electrical Pulses in Oncology: Irreversible Electroporation, Electrochemotherapy, Gene Electrotransfer, Electrofusion, and Electroimmunotherapy

This review summarizes the use of high-voltage electrical pulses (HVEPs) in clinical oncology to treat solid tumors with irreversible electroporation (IRE) and electrochemotherapy (ECT). HVEPs increase the membrane permeability of cells, a phenomenon known as electroporation. Unlike alternative ablative therapies, electroporation does not affect the structural integrity of surrounding tissue, thereby enabling tumors in the vicinity of vital structures to be treated. IRE uses HVEPs to cause cell death by inducing membrane disruption, and it is primarily used as a radical ablative therapy in the treatment of soft-tissue tumors in the liver, kidney, prostate, and pancreas. ECT uses HVEPs to transiently increase membrane permeability, enhancing cellular cytotoxic drug uptake in tumors. IRE and ECT show immunogenic effects that could be augmented when combined with immunomodulatory drugs, a combination therapy the authors term electroimmunotherapy. Additional electroporation-based technologies that may reach clinical importance, such as gene electrotransfer, electrofusion, and electroimmunotherapy, are concisely reviewed. HVEPs represent a substantial advancement in cancer research, and continued improvement and implementation of these presented technologies will require close collaboration between engineers, interventional radiologists, medical oncologists, and immuno-oncologists.

Irreversible Electroporation: Background, Theory, and Review of Recent Developments in Clinical Oncology

Irreversible electroporation (IRE) has established a clinical niche as an alternative to thermal ablation for the eradication of unresectable tumors, particularly those near critical vascular structures. IRE has been used in over 50 independent clinical trials and has shown clinical success when used as a standalone treatment and as a single component within combinatorial treatment paradigms. Recently, many studies evaluating IRE in larger patient cohorts and alongside other novel therapies have been reported. Here, we present the basic principles of reversible electroporation and IRE followed by a review of preclinical and clinical data with a focus on tumors in three organ systems in which IRE has shown great promise: the prostate, pancreas, and liver. Finally, we discuss alternative and future developments, which will likely further advance the use of IRE in the clinic.

Percutaneous cryoablation for the treatment of liver cancer at special sites: an assessment of efficacy and safety

Background

To assess the safety and efficacy of cryoablation (CA) devices for the treatment of liver cancer at special sites in a retrospective study.

Methods

Special site liver cancer was defined as the tumors directly abutting surrounding structures (such as the liver capsule, gallbladder, vessel, diaphragm, intestine, and adrenal gland) with a maximum distance of 1.0 cm between the tumor and these organs. Sixty-six patients (49 men, 17 women; mean age, 60.8 years; age range, 27-82 years) were included. CA procedure was performed to treat 69 tumors under the guidance of computed tomography or ultrasound. Local tumor progression was assessed during the follow-up. A visual analog scale (VAS) evaluated the pain degree. Complications were assessed during and after every procedure.

Results

The number of tumors under the liver capsule and adjacent to the gallbladder, portal or hepatic vein, diaphragm, intestine, and adrenal gland were 29, 5, 8, 14, 7, and 6, respectively. The median follow-up time was 14 months (range, 2-28 months). In the 69 procedures, the technical success rate was 100%. The cumulative local tumor progression rates at 6, 9, 15, and 24 months were 10.2%, 16.5%, 20.9%, and 30.5%, respectively. No cases of serious complications occurred. During operation, the occurrence rates of subcapsular hemorrhage and pneumothorax were 2.9% and 1.4%, respectively. After the operation, the occurrence rate of biloma, capsular injury, subcapsular planting metastasis, and pneumothorax were 1.4%, 18.8%, 1.4%, and 2.8%, respectively. The average score of 66 patients with a VAS was 2.15±0.63 during the operation.

Conclusions

Percutaneous CA is safe and effective for patients with special site liver cancer.

Simplified Non-Thermal Tissue Ablation With a Single Insertion Device Enabled by Bipolar High-Frequency Pulses

OBJECTIVE

To demonstrate the feasibility of a single electrode and grounding pad approach for delivering high frequency irreversible electroporation treatments (H-FIRE) in in-vivo hepatic tissue.

METHODS

Ablations were created in porcine liver under surgical anesthesia by adminstereing high frequency bursts of 0.5-5.0 μs pulses with amplitudes between 1.1-1.7 kV in the absence of cardiac synchronization or intraoperative paralytics. Finite element simulations were used to determine the electric field strength associated with the ablation margins (E_Lethal) and predict the ablations feasible with next generation electronics.

RESULTS

All animals survived the procedures for the protocol duration without adverse events. E_Lethal of 2550, 1650, and 875 V/cm were found for treatments consisting of 100x bursts containing 0.5 μs pulses and 25, 50, and 75 μs of energized-time per burst, respectively. Treatments with 1 μs pulses consisting of 100 bursts with 100 μs energized-time per burst resulted in E_Lethal of 650 V/cm.

CONCLUSION

A single electrode and grounding pad approach was successfully used to create ablations in hepatic tissue. This technique has the potential to reduce challenges associated with placing multiple electrodes in anatomically challenging environments.

SIGNIFICANCE

H-FIRE is an in situ tumor ablation approach in which electrodes are placed within or around a targeted region to deliver high voltage electrical pulses. Electric fields generated around the electrodes induce irrecoverable cell membrane damage leading to predictable cell death in the relative absence of thermal damage. The sparing of architectural integrity means H-FIRE offers potential advantages compared to thermal ablation modalities for ablating tumors near critical structures.

Normal and fibrotic liver parenchyma respond differently to irreversible electroporation

BACKGROUND

The safety and efficacy of irreversible electroporation (IRE) in treating hepatic, biliary, and pancreatic malignancies are active areas of clinical investigation. In addition, recent studies have shown that IRE may enable regenerative surgery and in vivo tissue engineering. To use IRE effectively in these clinical applications, it is important to understand how different tissue microenvironments impact the response to IRE. In this study, we characterize the electrical and histological properties of non-fibrotic and fibrotic liver parenchyma before and after IRE treatment.

METHODS

Electrical resistivity and histology of fibrotic liver from C57BL/6 mice fed a 0.1% 3,5-diethylcarbonyl-1,4-dihydrocollidine (DDC) diet were compared to those of non-fibrotic liver from matched control mice before and after IRE treatment.

RESULTS

At baseline, the electrical resistivity of fibrotic liver was lower than that of non-fibrotic liver. Post-IRE, resistivity of non-fibrotic liver declined and then recovered back to baseline with time, correlating with hepatocyte repopulation of the ablated parenchyma without deposition of fibrotic scar. In contrast, resistivity of fibrotic liver remained depressed after IRE treatment, correlating with persistent inflammation.

CONCLUSION

Non-fibrotic and fibrotic liver respond to IRE differently. The underlying tissue microenvironment is an important modifying factor to consider when designing IRE protocols for tissue ablation.

DWI and DCE-MRI approaches for differentiating reversibly electroporated penumbra from irreversibly electroporated ablation zones in a rabbit liver model

The purpose of our study was to investigate the hypothesis that DWI-MRI and DCE-MRI cab be used to distinguish between IRE and RE zones of IRE treatment in a rabbit liver model. 6 rabbits underwent baseline and post-procedure MR imaging with DWI and DCE-MRI as well as IRE (10 pulses, 2000 V, 10 µs/pulse, 10 ms between pulses). Rabbits were euthanized immediately after post-procedure MRI to acquire liver tissue for histology. Liver tissues were fixed and then stained with HE and TUNEL. T1w and T2w intensities in different treatment zones were calculated and normalized to paraspinal muscle signal. ADC maps were generated from DWI. AUC, PE, TTP, WIS, K_trans, K_ep, and V_E were calculated from DCE-MRI. Apoptosis index was calculated from TUNEL stained tissues. P<0.05 was considered statistically significant. Entire IRE treated region was hyperintense compared with untreated tissues on T1w, with the RE zone having a higher signal intensity. On DWI, IRE treated tissue had decreased ΔADC. The IRE zone has a lower ΔADC than the RE zone within the treated region. On DCE-MRI, IRE zone demonstrated the highest TTP and the lowest PE, WIS, K_trans, K_ep, and V_E, followed by the RE zone then the untreated tissue. TUNEL staining of liver tissues showed that the IRE zone had the highest apoptosis index, followed by the RE zone and then untreated tissue. In conclusion, DCE-MRI and DWI parameters allow differentiation between RE and IRE zones in a rabbit liver model.

Multidisciplinary management of liver metastases in patients with colorectal cancer: a consensus of SEOM, AEC, SEOR, SERVEI, and SEMNIM

Colorectal cancer (CRC) has the second-highest tumor incidence and is a leading cause of death by cancer. Nearly 20% of patients with CRC will have metastases at the time of diagnosis, and more than 50% of patients with CRC develop metastatic disease during the course of their disease. A group of experts from the Spanish Society of Medical Oncology, the Spanish Association of Surgeons, the Spanish Society of Radiation Oncology, the Spanish Society of Vascular and Interventional Radiology, and the Spanish Society of Nuclear Medicine and Molecular Imaging met to discuss and provide a multidisciplinary consensus on the management of liver metastases in patients with CRC. The group defined the different scenarios in which the disease can present: fit or unfit patients with resectable liver metastases, patients with potential resectable liver metastases, and patients with unresectable liver metastases. Within each scenario, the different strategies and therapeutic approaches are discussed.

Irreversible Electroporation For Liver Tumors: A Review Of Literature

The prevalence of liver tumors is increasing worldwide. These can be broadly classified into primary and secondary types, depending upon the origin of the tumor. Multiple modalities are available for the management of these tumors. Ablative techniques are becoming the cornerstone of management especially for the tumors which are unresectable. Thermal ablative techniques include radiofrequency ablation (RFA), microwave ablation (MWA), and cryotherapy. Recently, a non-thermal technique known as irreversible electroporation (IRE) is gaining importance owing to its better clinical outcome and a good safety profile. IRE works by high voltage and intensity electrical discharge which makes pores in the membrane of the cells. Its clinical outcome is reported in different studies in terms of progression-free survival (PFS), frequency of complete ablation, and local recurrence of the tumor. Favorable results were seen especially for the small size tumors and very early hepatocellular carcinoma (HCC). It was also found to be useful for the management of tumors which are close to vital structures of the liver. The adverse effects of IRE are also comparable to other ablative techniques like RFA and MWA. The common complications associated with this procedure include liver abscess, bleeding, renal failure, pleural effusion, fever, and partial portal vein thrombosis. In view of this literature review, IRE is found to be a good alternative for the management of liver tumor in patients who cannot undergo surgery, thermal ablative procedures or tumor lying close to vital structures. The safety profile of this procedure is also encouraging. Further studies and clinical trials need to be done to explore this technique.

Therapeutic Effect of Irreversible Electroporation in Combination with Poly-ICLC Adjuvant in Preclinical Models of Hepatocellular Carcinoma

PURPOSE

To evaluate the therapeutic efficacy of irreversible electroporation (IRE) combined with the intratumoral injection of the immunogenic adjuvant poly-ICLC (polyinosinic-polycytidylic acid and poly-L-lysine, a dsRNA analog mimicking viral RNA) inmediately before IRE.

MATERIALS AND METHODS

Mice and rabbits bearing hepatocellular carcinoma tumors (Hepa.129 and VX2 tumor models, respectively) were treated with IRE (2 pulses of 2500V), with poly-ICLC, or with IRE + poly-ICLC combination therapy. Tumor growth in mice was monitored using a digital caliper and by computed tomography in rabbits.

RESULTS

Intratumoral administration of poly-ICLC immediately before IRE elicited shrinkage of Hepa.129 cell-derived tumors in 70% of mice, compared to 30% and 26% by poly-ICLC or IRE alone, respectively (P = .0004). This combined therapy induced the shrinkage of VX-2-based hepatocellular carcinoma tumors in 40% of rabbits, whereas no response was achieved by either individual treatment (P = .045). The combined therapy activated a systemic antitumor response able to inhibit the growth of other untreated tumors.

CONCLUSIONS

IRE treatment, immediately preceded by the intratumoral administration of an immunogenic adjuvant such as poly-ICLC, might enhance the antitumor effect of the IRE procedure. This combination might facilitate the induction of a long-term systemic response to prevent tumor relapses and the appearance of metastases.

A Conceivable Mechanism Responsible for the Synergy of High and Low Voltage Irreversible Electroporation Pulses

Irreversible electroporation (IRE), is a new non-thermal tissue ablation technology in which brief high electric field pulses are delivered across the target tissue to induce cell death by irreversible permeabilization of the cell membrane. A deficiency of conventional IRE is that the ablation zone is relatively small, bounded by the irreversible electroporation isoelectric field margin. In the previous studies we have introduced a new treatment protocol that combines few short high voltage (SHV) pulses with long low-voltage (LLV) pulses. In the previous studies, we also have shown that the addition of few SHV pulses increases by almost a factor of two the area ablated by a protocol that employs only the LLV pulses. This study employs potato and gel phantom to generate a plausible explanation for the mechanism. The study provides circumstantial evidence that the mechanism involved is the production of electrolytic compounds by the LLV pulse sequence, which causes tissue ablation beyond the margin of the irreversible electroporation isoelectric field generated by the SHV pulses, presumable to the reversible electroporation isoelectric field margin generated by the SHV pulses.

Is irreversible electroporation safe and effective in the treatment of hepatobiliary and pancreatic cancers?

BACKGROUND

Irreversible electroporation (IRE) is a novel ablative technique for hepatobiliary and pancreatic cancers. This review summarizes the data regarding the safety and efficacy of IRE in the treatment of hepatobiliary and pancreatic cancers.

DATA SOURCES

Studies were identified by searching PubMed and Embase for articles published in English from database inception through July 31, 2017. For inclusion, each clinical study had to report morbidity and survival data on hepatobiliary and pancreatic cancers treated with IRE and contain at least 10 patients. Studies that met these criteria were included for analysis. Two authors assessed each clinical study for data extraction. The controversial parts were resolved through discussion with seniors.

RESULTS

A total of 24 clinical studies were included. Fourteen focused on hepatic ablation with IRE comprising 437 patients with 666 lesions of different tumor types. Two patients (0.5%) died after the IRE procedure. Morbidity of hepatic ablation with IRE ranged from 7% to 35%. Most complications were mild. Complete response for hepatic tumors was reported as 57%-97%. Ten studies with 455 patients focused on pancreatic IRE. The overall mortality of IRE in pancreatic cancer was 2%. Overall severe morbidity of IRE in pancreatic cancer ranged from 0 to 20%. The median overall survival after IRE ranged from 7 to 23 months. Patients treated with IRE combined with surgical resection showed a longer overall survival.

CONCLUSIONS

IRE significantly improves the prognosis of advanced hepatobiliary and pancreatic malignances, and companied with less complications. Hence, IRE is a relatively safe and effective non-thermal ablation strategy and potentially recommended as an option for therapy of patients with hepatobiliary and pancreatic malignances.

Current State of Tumor Ablation Therapies

The most common primary liver malignancy, hepatocellular carcinoma (HCC), has a high likelihood of mortality, and much effort into early detection and treatment has occurred. Multiple staging systems have surfaced of which some guide treatment. Curative intent is a goal of early-staged HCC treatment, and this can be achieved with surgical resection, liver transplantation, and minimally invasive percutaneous therapies such as tumor ablation. Many of the newer ablation techniques have evolved from shortcomings of prior methods which have resulted in an expanded number of applications for tumor ablation. Our review focuses on current mainstream image-guided percutaneous ablation modalities which are commonly performed as an alternative to surgery.

Numerical workflow of irreversible electroporation for deep-seated tumor

The paper provides a numerical workflow, based on the 'real-life' clinical workflow of irreversible electroporation (IRE) performed for the treatment of deep-seated liver tumors. Thanks to a combination of numerical modeling, image registration algorithm and clinical data, our numerical workflow enables to provide the distribution of the electric field as effectively delivered by the clinical IRE procedure. As a proof of concept, we show on a specific clinical case of IRE ablation of liver tumor that clinical data could be advantageously combined to numerical simulations in a near future, in order to give to the interventional radiologists information on the effective IRE ablation. We also corroborate the simulated treated region with the post-treatment MRI performed 3 d after the treatment.