Application of Irreversible Electroporation Ablation as Adjunctive Treatment for Margin Enhancement: Safety and Efficacy

Liver-tumor mimics as a potential translational framework for planning and testing irreversible electroporation with multiple electrodes

Irreversible electroporation (IRE) has emerged as an appealing non-ionizing, non-thermal ablation therapy, independent of antineoplastic drugs. Limited but successful outcomes in IRE conducted in vivo, in small focal hepatocellular carcinomas (HCC), have been reported. Nonetheless, the electric parameters of IRE are usually delivered in an unplanned manner. This work investigates the integration of computational modeling to hydrogels mimicking the HCC microenvironment, as a powerful framework to: circumvent ethical concerns of in vivo experimentation; safely tune the electric parameters reaching the IRE electric field threshold; and propel the translation of IRE as a routine clinical alternative to the treatment of HCC. Therefore, a parametric study served to evaluate the effects of the pulse amplitude, the number of pulses and electrodes, the treatment time, the hydrogel-tumor size, and the cell type. The ablation extent was surveyed by confocal microscopy and magnetic resonance imaging (MRI) in cylindrical and realistic tumor-shaped hydrogels, respectively. A large ablation (70%-100%) was verified in all constructs.

State-of-the-Art and Upcoming Innovations in Pancreatic Cancer Care: A Step Forward to Precision Medicine

Pancreatic cancer remains a social and medical burden despite the tremendous advances that medicine has made in the last two decades. The incidence of pancreatic cancer is increasing, and it continues to be associated with high mortality and morbidity rates. The difficulty of early diagnosis (the lack of specific symptoms and biomarkers at early stages), the aggressiveness of the disease, and its resistance to systemic therapies are the main factors for the poor prognosis of pancreatic cancer. The only curative treatment for pancreatic cancer is surgery, but the vast majority of patients with pancreatic cancer have advanced disease at the time of diagnosis. Pancreatic surgery is among the most challenging surgical procedures, but recent improvements in surgical techniques, careful patient selection, and the availability of minimally invasive techniques (e.g., robotic surgery) have dramatically reduced the morbidity and mortality associated with pancreatic surgery. Patients who are not candidates for surgery may benefit from locoregional and systemic therapy. In some cases (e.g., patients for whom marginal resection is feasible), systemic therapy may be considered a bridge to surgery to allow downstaging of the cancer; in other cases (e.g., metastatic disease), systemic therapy is considered the standard approach with the goal of prolonging patient survival. The complexity of patients with pancreatic cancer requires a personalized and multidisciplinary approach to choose the best treatment for each clinical situation. The aim of this article is to provide a literature review of the available treatments for the different stages of pancreatic cancer.

Pulsed Electric Fields in Oncology: A Snapshot of Current Clinical Practices and Research Directions from the 4th World Congress of Electroporation

The 4th World Congress of Electroporation (Copenhagen, 9-13 October 2022) provided a unique opportunity to convene leading experts in pulsed electric fields (PEF). PEF-based therapies harness electric fields to produce therapeutically useful effects on cancers and represent a valuable option for a variety of patients. As such, irreversible electroporation (IRE), gene electrotransfer (GET), electrochemotherapy (ECT), calcium electroporation (Ca-EP), and tumour-treating fields (TTF) are on the rise. Still, their full therapeutic potential remains underappreciated, and the field faces fragmentation, as shown by parallel maturation and differences in the stages of development and regulatory approval worldwide. This narrative review provides a glimpse of PEF-based techniques, including key mechanisms, clinical indications, and advances in therapy; finally, it offers insights into current research directions. By highlighting a common ground, the authors aim to break silos, strengthen cross-functional collaboration, and pave the way to novel possibilities for intervention. Intriguingly, beyond their peculiar mechanism of action, PEF-based therapies share technical interconnections and multifaceted biological effects (e.g., vascular, immunological) worth exploiting in combinatorial strategies.

Clinical Results, Risk Factors, and Future Directions of Ultrasound-Guided Percutaneous Microwave Ablation for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, with a relatively poor prognosis, especially for advanced HCC. With the availability of a variety of treatment options, the treatment strategies for HCC have become more and more diversified. Microwave ablation (MWA) has gradually been considered as a viable alternative to surgical resection (SR) owing to its comparable long-term survival, reduced complications, and greater preservation of hepatic parenchyma. However, clinical outcomes, tumor progression, and recurrence of HCC after MWA remain major concerns. Here, after reviewing the current therapeutic options for HCC, we focus on MWA, describing the advantages and challenges of MWA and the clinical results after treatment. We then focused on prognostic factors that influence post-ablation clinical outcomes and briefly presented the strategy of MWA for future clinical treatment.

Percutaneous transhepatic cholangial drainage/percutaneous transhepatic biliary stent implantation for treatment of extrahepatic cholangiocarcinoma with obstructive jaundice

Extrahepatic cholangiocarcinoma is a malignant tumor originating from the extrahepatic bile duct including the hilar region to the lower bile duct of the common bile duct. With the development of interventional techniques and medical materials, percutaneous transhepatic cholangial drainage (PTCD) or percutaneous transhepatic biliary stent implantation (PTBS) has become the main treatment to relieve biliary obstruction. However, the occurrence of postoperative complications seriously affects the prognosis of patients, and the combination of biliary stenting with local treatment has been found to significantly prolong the time to biliary patency. This article reviews the progress of PTCD/PTBS in the treatment of extrahepatic cholangiocarcinoma with obstructive jaundice, evaluates its clinical efficacy, and points out the current problems and posible solutions to provide more reference for subsequent related studies.

Intratumoral electroporation of a self-amplifying RNA expressing IL-12 induces antitumor effects in mouse models of cancer

Alphavirus vectors based on self-amplifying RNA (saRNA) generate high and transient levels of transgene expression and induce innate immune responses, making them an interesting tool for antitumor therapy. These vectors are usually delivered as viral particles, but it is also possible to administer them as RNA. We evaluated this possibility by in vivo electroporation of Semliki Forest virus (SFV) saRNA for local treatment of murine colorectal MC38 subcutaneous tumors. Optimization of saRNA electroporation conditions in tumors was performed using an SFV vector coding for luciferase. Then we evaluated the therapeutic potential of this approach using an SFV saRNA coding for interleukin-12 (SFV-IL-12), a proinflammatory cytokine with potent antitumor effects. Delivery of SFV-IL-12 saRNA by electroporation led to improvement in tumor control and higher survival compared with mice treated with electroporation or with SFV-IL-12 saRNA alone. The antitumor efficacy of SFV-IL-12 saRNA electroporation increased by combination with systemic PD-1 blockade. This therapy, which was also validated in a hepatocellular carcinoma tumor model, suggests that local delivery of saRNA by electroporation could be an attractive strategy for cancer immunotherapy. This approach could have easy translation to the clinical practice, especially for percutaneously accessible tumors.

Margin ACcentuation for resectable Pancreatic cancer using Irreversible Electroporation - Results from the MACPIE-I study

INTRODUCTION

Margin accentuation (MA) using Irreversible electroporation (IRE) offers an unique opportunity to reduce the R1 resections in resectable pancreatic cancer (RPC). This study aims to assess the rate of margin positivity using IRE for MA during pancreaticoduodenectomy (PD) for resectable pancreatic head tumours.

MATERIALS AND METHODS

Following ethical approval, MA using IRE was carried out in 20 consecutive patients to posterior and superior mesenteric vein (SMV) margin, and the pancreatic neck, prior to the PD resection. The control group (non-IRE; n = 91) underwent PD without MA over the study period, March 2018 to March 2020.

RESULTS

There was no difference between the two groups in terms of patients' age, gender, pre-op biliary drainage, site of malignancy or pre-operative TNM stage. The overall margin positive rate for IRE group was lesser (35.0%) when compared to non-IRE group (51.6%; p = 0.177), with significantly less posterior pancreatic margin positivity (5.0% vs. 25.3%; p = 0.046). When only treated margins (SMA margin excluded) were compared, the IRE group had significantly lower margin positive rates (20.0% vs. 51.6%; p = 0.013). There was no difference between the two groups in terms of intra- or post-operative complications. With a median follow-up of 15.6 months, the median DFS and OS for IRE and non-IRE groups were 17 and 18 months (p = 0.306) and 19 and 22 months (p = 0.227) respectively.

CONCLUSION

Our pilot study confirms the safety of MA using IRE for RPC, with reduction in margin positivity. These results as a proof of concept are promising and need further validation with a randomised controlled trial.

Locally Advanced Pancreatic Cancer: Percutaneous Management Using Ablation, Brachytherapy, Intra-arterial Chemotherapy, and Intra-tumoral Immunotherapy

PURPOSE OF REVIEW

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive neoplasms, bearing a terrible prognosis. Stage III tumors, also known as locally advanced pancreatic cancer (LAPC), are unresectable, and current palliative chemotherapy regimens have only modestly improved survival in these patients. At this stage of disease, interventional techniques may be of value and further prolong life. The aim of this review was to explore current literature on locoregional percutaneous management for LAPC.

RECENT FINDINGS

Locoregional percutaneous interventional techniques such as ablation, brachytherapy, and intra-arterial chemotherapy possess cytoreductive abilities and have the potential to increase survival. In addition, recent research demonstrates the immunomodulatory capacities of these treatments. This immune response may be leveraged by combining the interventional techniques with intra-tumoral immunotherapy, possibly creating a durable anti-tumor effect. This multimodality treatment approach is currently being examined in several ongoing clinical trials. The use of certain interventional techniques appears to improve survival in LAPC patients and may work synergistically when combined with immunotherapy. However, definitive conclusions can only be made when large prospective (randomized controlled) trials confirm these results.

Effect of Margin Status on Survival After Resection of Hilar Cholangiocarcinoma in the Modern Era of Adjuvant Therapies

INTRODUCTION

Studies have shown that for patients with hilar cholangiocarcinoma (HC), survival is associated with negative resection margins (R0). This requires increasingly proximal resection, putting patients at higher risk for complications, which may delay chemotherapy. For patients with microscopically positive resection margins (R1), the use of modern adjuvant therapies may offset the effect of R1 resection.

METHODS

Patients at our institution with HC undergoing curative-intent resection between January 2008 and July 2019 were identified by retrospective record review. Demographic data, operative details, tumor characteristics, postoperative outcomes, recurrence, survival, and follow-up were recorded. Patients with R0 margin were compared to those with R1 margin. Patients with R2 resection were excluded.

RESULTS

Seventy-five patients underwent attempted resection with 34 (45.3%) cases aborted due to metastatic disease or locally advanced disease. Forty-one (54.7%) patients underwent curative-intent resection with R1 rate of 43.9%. Both groups had similar rates of adjuvant therapy (56.5% vs. 61.1%, P = .7672). Complication rates and 30 mortality were similar between groups (all P > .05). Both groups had similar median recurrence-free survival (R0 29.2 months vs. R1 27.8 months, P = .540) and median overall survival (R0 31.2 months vs. R1 38.8 months, P = .736) with similar median follow-up time (R0 29.9 months vs. R1 28.5 months, P = .8864).

CONCLUSIONS

At our institution, patients undergoing hepatic resection for HC with R1 margins have similar recurrence-free and overall survival to those with R0 margins. Complications and short-term mortality were similar. This may indicate that with use of modern adjuvant therapies obtaining an R0 resection is not an absolute mandate.

Intraprocedural Transcatheter Intraarterial Perfusion (TRIP)-MRI for Evaluation of Irreversible Electroporation Therapy Response in a Rabbit Liver Tumor Model

Purpose

Irreversible electroporation (IRE) is a promising new ablation method for hepatocellular carcinoma (HCC) treatment with few side-effects; however, tissue perfusion and differentiation between treatment zones have not been sufficiently studied. In this project, we analyzed HCC tumor perfusion changes immediately after IRE treatment using transcatheter intraarterial perfusion (TRIP)-MRI to monitor treatment zone margins.

Materials and Methods

All protocols were approved by the institutional animal care and use committee. A total of 34 rabbits were used for this prospective study: tumor liver group (n=17), normal liver group (n=14), and 3 for growing VX2 tumors. All procedures and imaging were performed under anesthesia. VX2 tumors were grown by injection of VX2 cells into rabbit hindlimbs. Liver tumors were induced by percutaneous US-guided injection of VX2 tumor fragments into liver. For digital subtraction angiography (DSA), a 2F catheter was advanced through left hepatic artery via femoral artery access, followed by contrast injection. All rabbits underwent baseline anatomic MRI, then IRE procedure or IRE probe placement only, and lastly post-procedure anatomic and TRIP-MRI. Liver tissues were dissected immediately after imaging for histology. All statistical analyses were performed on GraphPad Prism, with P<0.05 considered significant.

Results

IRE generated central IRE zone and peripheral reversible electroporation (RE) zone on anatomic MRI for both normal liver and liver tumor tissues. The semiquantitative analysis showed that IRE zone had the lowest AUC, PE, WIS, K^trans, v_e , and v_p as well as the highest TTP, followed by RE zone, then untreated tissues. Receiver operating characteristic analysis showed that WIS and AUC₆₀ had the highest AUC_ROC. Histologic analysis showed a positive correlation in viable area fraction between MRI and histologic measurements. IRE zone had the highest %apoptosis and lowest CD31+ staining.

Conclusion

Our results demonstrated that intraprocedural TRIP-MRI can effectively differentiate IRE and RE zones after IRE ablation in normal liver and liver tumor tissues.